: Main Bearing pics



Pjs
11-03-04, 05:53 PM
After getting a new oil manifold I opted to go for the case 1/2 seals too. Here are some pics of the bearings, I don't think they look to bad for 137K, but the new ones are $50 a pr. and that is definitely outta the question at this point in time. The bearing surface is still completely smooth.
I can't believe how sweet the timing chains and tensioners look, almost like brand new. I did a visual on the bores as much as I could and the crosshatch is still very visible.

BeelzeBob
11-03-04, 11:02 PM
The bearings look fine. All you are seeing is some marking of the overplate on the bearing surface. It is only a few microns thick so it marks easily and typically will look like that just after breakin. Pretty good main bearing life to look like that this far along, eh...???

The mains can be reused but the rod bearings CANNOT be reused. If you disturbed or dissassembled any of the rod bearings to look at them or inspect them you have to replace them or they will fail later. The crush used in the rod bearings make them a throwaway if they are torqued into the rods and the engine is run and thermocycled. Hopefully you did not take any rods apart.

Put the LCC(lower crank case) back on with the new seals and the red, anearobic sealer along the sides of the joint outside of the LCC seals. The anearobic sealant is really redundant but does help make the joint totally dry. Use a dab of RTV at the rear main seal where it contacts the LCC side seals. One hint for an easier reassembly is to slide the rear main seal onto the crank, put the dabs of RTV at the side seal intersection and then install the LCC with the rear main seal already in place. Otherwise you will have to use the special installation tool to seat the rear main seal as it is a press fit.

dkozloski
11-04-04, 12:20 AM
bbobnski, the crush on the rod bearings is why I always cringed at the idea of using Plastigage to measure bearing clearances. The multiple assembling always worried me. I would carefully measure journal diameters, the saddle or big end diameter, and measure the thickness of the bearing shell with a tubing wall thickness mike. The final check was how everything felt as the bolts were tightened. I never had a bearing failure in hundreds and hundreds of engine overhauls.

96 STS
11-04-04, 12:27 AM
DUDE!!! I just have to say that you give encouragement, enthusiasm, and peace of mind to all of us with high mileage Caddys.

Mine has almost 168k and while it really runs good & seems to have been well maintained, I still worry about the future possibilities due to the high mileage. I've never owned a car with this kind of mileage before, and my past vehicles have tended to begin dying at around 130-140k.

I do have a Montero Sport that I've owned from 65k up to the 134k currently with absolutely no problems, so I AM luckly on that one so far. I just hope it continues to last.

Seeing the mains on your n* looking so good w/ 137k definitely eases my mind about mine. Please keep posting your progress. I've become eager for you to get your Caddy back on the road.

Cheers,
96 STS

Pjs
11-04-04, 08:28 AM
Bbob, Thanks for checking this post. Your opinion really gives me some piece of mind. I think the bearings look pretty good, I've added a couple callouts to give perspective. You can see a dog hair and a strand of cotton from a shop rag. I did follow the book when replacing the LLC. I didn't use the anerobic sealer, I did place the rear main on before bolting the case together but forgot to dab the RTV on the T joint (Stupid). I got as far as torqueing the main bolts down when I realized I hadn't picked up a new pick up tube o-ring. I stopped by the Chev dealer yesterday and got my new rings, but in the converstation the parts guy was telling me that he rememebered a TSB that said the pick up tube & baffle had to be replaced because of the new oil manifold. I have a subscription to alldata and checked all the TSB's listed there and didn't find one. The only difference in the old and new oil manifolds that I could see was the molded in seal around the pick up tube. I'm going to go by the Stealership this morning and double check. As long as I'm where I'm at I can pull it apart again and use the anerobic sealer. Is that something that I can only get @ the dealer?

Pjs
11-04-04, 08:57 AM
DUDE!!! I just have to say that you give encouragement, enthusiasm, and peace of mind to all of us with high mileage Caddys.

Please keep posting your progress. I've become eager for you to get your Caddy back on the road.

Dude..I really have to thank you....your the one of the people who's been giving me encouragement to keep going deeper into this, Thanks :thumbsup:
My last caddy, 91 Brougham had 184K on it when I sold it. It had the 305 chev in it and I wouldn't have hesitated to drive it clear to Calif from Tenn, it really held up well. I was really surpised to find this engine in this good of shape when I took it apart and I can see where it's feasible to get another 100K out of it.
It's been over 10 yrs since I've worked as a mechanic and I thought I'd forgotten how to do this kind of work. After I had installed the powertrain the first time and it was still leaking I was so ready to throw in the towel, but opted to just bite the bullet and do it again. The second time as a lot easier and I got done in 6hrs what took me 3 days to do the first time. I just want to thank all you guys for giving me the determination and and encouragement to get this project done, and done right. :)

duecentoi
11-04-04, 01:08 PM
The mains can be reused but the rod bearings CANNOT be reused. If you disturbed or dissassembled any of the rod bearings to look at them or inspect them you have to replace them or they will fail later. The crush used in the rod bearings make them a throwaway if they are torqued into the rods and the engine is run and thermocycled.


What are you talking about? Are you trying to say that the Northstar rods and/or bearings are somehow different from everything else? I hate to be the one to break this to you but the mains have "crush" holding them in place as well. I have taken literally hundreds of motors apart for service and NEVER have I seen a used rod bearing fail after reassembly, if the rod bearing was servicable to start with. Unless there is something radicaly different about the Northstar rods, you guys are passing around a bunch of Urban Myth and Mountain Medicine.

BTW If what you are saying were true the Plasti-gage people would have been long sued out of existance. What is vital is that the crank and bearings be spotlessly clean and that the bore and the backs of the bearings be clean and dry. The bearings in the pictures show lots of signs of "trash" in the oil. The light scoring evident is from contact between crank and bearing when the oil "wedge" is lost or not yet established, such as cold starts. It is quite problematic to attempt a diagnosis from such pictures, but I would probably consider replacing the mains as long as I had them out. Bearings that have always been run with clean oil and never suffered a loss of oil pressure will usually only show a small polished area. Such a wide "wipe" of the bearing material usually indicates inferquent oil changes.

dkozloski
11-04-04, 01:48 PM
duecentoi, my experience is with aircraft engines that run for long periods of time at high power settings and thus high stresses. I did engine teardown and failure analysis for the FAA and NTSB for years. The rod failure mechanism is as follows: The rod bearing is held in place by crush. The tang only serves to position the bearing at assembly. A used rod and bearing are reassembled. The crush has been relieved slightly by the process. The bearing doesn't spin but moves ever so slightly in the bore. The movement produces metal fret and eventually pinpoint areas of galling in the rod bore. At this pinpoint of galling the fatigue crack starts. Once the crack starts the rod fails in short order. High powered, geared Lycoming engines are particularly prone to this type of failure. I have seen this type of failure in connecting rods that were not assembled with used parts but did have enough oil on the back side of the bearings that was trapped at assembly and resulted in excessive crush and looseness when the oil seeped out. Ask someone in the aircraft engine overhaul business if you can look at their Lycoming Service Bulletins and Instructions. I am sure that you will have your eyes opened. This type of failure is seldom seen in the automotive field because car engines loaf along at part throttle and only produce at maximum for short bursts. In one instance involving a twin engine Aerocommander, shortly after one engine failed in this manner the second also failed while putting out full power to compensate for the first. It appears that your experience is far too parochial for you to be criticizing others and making broad generalizations about their judgement and experience. I agree that the same problem exists with the mains and I have actually seen more main bearings come loose and chew up the saddles than rod failures although this usually results in a lot of warning from metal in the oil rather than a catastrophic failure like a broken rod.

Pjs
11-04-04, 02:41 PM
The bearings in the pictures show lots of signs of "trash" in the oil. The light scoring evident is from contact between crank and bearing when the oil "wedge" is lost or not yet established, such as cold starts. It is quite problematic to attempt a diagnosis from such pictures, but I would probably consider replacing the mains as long as I had them out. Bearings that have always been run with clean oil and never suffered a loss of oil pressure will usually only show a small polished area. Such a wide "wipe" of the bearing material usually indicates inferquent oil changes.
I know the pictures really a hard gauge but I'm not really trying to diagnose anything. I thought y'all would like to see what these would look like @ the milage of this engine. The previous owners oil changes possibly may have been infrequent, but at the rate at which this thing leaked oil (and there is NO sign of oil starvation anywhere) coupled with the fact that there is no dirt, grime, sludge or any other contaminates in the engine indicates to me that there has been clean oil all along. The bearing surfaces look scored in the photos, but you can't feel anything but smooth, even with your fingernail. The cams, timing components and every other surface on the interior of this engine exhibit only a slight varnish discoloration.

dkozloski
11-04-04, 03:07 PM
The pictures you show are textbook examples of good servicable used automotive type main bearing. There is no distress indicated.

BeelzeBob
11-04-04, 07:52 PM
I agree. I have reviewed 100's of engine teardowns with high miles and hard usage. Your main bearings look fine and do not indicate any sort of trash or debris in the oil nor do they indicate any sort of problem. They look perfectly normal especially for the miles you have on them. The wear or contact area looks perfect. Notice that there is no contact at the split line of the bearing. That is as designed. The split line is where the oil film is established. Oil can enter between the bearing surface and the crank at that point and the rotation of the crank creates the bearing film as the crank rotates under load. The width of the contact area looks fine as well as the length of the contact around the perimeter of the bearing shell. Funny thing is that I bet that when you look at them in another 100K they will look the same....!!!


duecentoi...what I am talking about is that the Northstar rod bearings have more crush than the "normal" engine you may have taken apart over the past century. The crush in the bearing (the OD of the bearing shells is slightly greater than the ID of the bearing bore in the rod) is what holds it in place....it is the only thing holding it in place from moving and spinning. The tang is simply an assembly aid and alignment feature...it does absolutely nothing in maintaining bearing position. During engine development we often use bearings with no tang and/or file off the tang to change bearing alignment or orientation with absolutely no consequences. Typically, rod bearings in the past ran about .0002-.0003 crush on the diameter. During Northstar engine development it was notices that the rod bearings were moving slightly in the bores...not enough that the bearings actually moved position but enough that areas of micro-fretting developed on the backside of the rod bearing shells....material transfer from the rod to the steel back of the bearing indicating microscopic movement of the bearing as it "squirmed" in the bearing bore under load. 100's of hours on the dyno at 6500 RPM and 300 HP continuously will show you things like this. These engines are validated on a test that runs at 6000 for 400 hours at full throttle continuously....they have to endure FAR FAR more than a 15 second dyno "pull" on the speedshop's water brake dyno. The microscopic movement of the bearing indicated that more clamp load or crush was needed in the bearing. The crush was increased to the .0003-.0004 range. This solved the microfretting problem on the backside of the bearing. Microfretting like this can commonly be seen on high performance race engines as it appears as a black area on the back of the bearing shell and if left alone long enough it will actually transfer tiny chunks of material. Eventually this microfretting on the backside of the bearing will casue the rod to fail as the microscopic pits caused by the material welding or transfer causes a stress riser that a crack propogates from. Seen it happen many times.....no LOL.

The down side to the extra crush is that the bearing is put into such a high compression when assembled that it actually takes a slight "set" if the engine is run and the bearing subjected to high loads and high temperatures. It happens, trust me. Every time I have ever seen a Northstar dyno engine taken apart and the rod bearings reused the engine would eventually fail a rod bearing. This did not have to happen too many times to teach us that you do not reuse the high crush rod bearings over again if the rod is taken apart. I saw this with my own eyes, have measured the bearings and know that it happens.

One could probably take an engine from a street driven Northstar, dissassemble and reassemble the rod bearings and maybe get away with it 75% of the time as the engine will never be run as hard on the street....but....why risk it. It is a known failure mode in a high stress situation. Some mechanic will say that he has done this, I am sure, and no problems were seen but the next time he may not be so lucky if the driver runs the engine to redline like it is designed for...... Personally, I would NEVER reuse a rod bearing on any engine especially a Northstar. I have seen the results or reassembling Northstar rods with used bearings. Not in my engine so that is the reason I recommend what I do.

The main bearings for the Northstar, if you look carefully, are somewhat unique. They have a very very thick (4mm) steel backing or shell. This is done because of the all aluminum construction of the block and lower crankcase. The main bearing bore is all aluminum. Aluminum expands a great deal more than cast iron or steel as the temperature changes. Correspondingly, the main bearing clearance on the crank would change significantly with temperature if there were no design changes made to prevent it. What was done was to make the main bearing shells with very thick steel backing (4 mm vs. 1 or 1.5 mm on conventional mains) so that they can handle a tremendous amount of crush without distorting. So...the main bearing clearance is set up for a hot engine and as the engine cools toward a minus 40 cold start in Kapuskasing the bearing can handle the extreme load the shrinking aluminum exerts on it without collapsing and causing the bearing clearance to shrink to zero. That is why the thrust bearing on the Northstar crank is three pieces instead of the normal thrust main bearing that has the sides/thrust face simply folded over. The 4mm backing is too thick to fold over for the thrust face sides so the thrust faces are separate "fences" staked into place.

So...even though the mains in the Northstar are set up with a large amount of crush they can be safely reused due to the 4mm thick steel backing. The thick backing resists any permanent distortion from the crush. It is perfectly fine to reuse the mains.

The rod bearing shells should never ever be reused. They do NOT have the same thick steel backing and do take a set with use and will not have the adequate crush if dissassembled and reused. If reused, it will likely lead to a rod failure due to stress risers forming in the rod bearing bore due to microfretting of the bearing against the bearing bore.

The recommendation is based on fact, observation and sound engineering. It is not a bunch of Urban Myths nor Mountain Medicine. There really is something radicaly different about the Northstar rods......



Personally, I have little faith in plastigage...it is of some general use I suppose but it is really not that accurate. I don't mind the dry assembly and dissassembly of the rod/rod bearing for clearance checks as long as the bearing is not put under load against the crank and subjected to any heat. It will not take a set under those conditions of temporary assembly for clearance checks.


If you look at the pictures of the bearing shells in the post above you can make out the thick steel backing I mentioned.

The "marks" that look like scoring are just marks in the tin overplate that is put on the bearings for breakin. The fact is that the bearings look so good that the breakin overplate is not even completely worn away...it is just removed in streaks that look like scoring. The bearings are fine.

BeelzeBob
11-04-04, 07:56 PM
Remember when you reassemble the engine that you need to pull the damper on with a puller and that the large bolt that holds the damper on needs to be VERY tight. It takes about 250-300 ftlb to get the bolt to the torque-angle spec required. Otherwise the oil pump drive sleeve can slip and cause the engine to loose oil pressure.


Don't those sprockets look great after all those miles....LOL Just the way we planned it.

The chain guides should have a "mark" where the side plates of the chains ride. That is normal. That happens almost immediately when the engine is first run and stays that way forever.

Sinister Angel
11-04-04, 08:11 PM
Those bearings look great!

So the bearing material is aluminum with a steel backing as compared to babbit or something of the sort?

D148L0
11-04-04, 08:13 PM
Bbob, once again you show why you are so appreciated here. Not only because of your knowledge but your patience as well.
Urban legends. Mountain medicine. It was not directed to me, and even so, I got mad...
Kudos to you.

BeelzeBob
11-04-04, 08:14 PM
Bbob, Thanks for checking this post. Your opinion really gives me some piece of mind. I think the bearings look pretty good, I've added a couple callouts to give perspective. You can see a dog hair and a strand of cotton from a shop rag. I did follow the book when replacing the LLC. I didn't use the anerobic sealer, I did place the rear main on before bolting the case together but forgot to dab the RTV on the T joint (Stupid). I got as far as torqueing the main bolts down when I realized I hadn't picked up a new pick up tube o-ring. I stopped by the Chev dealer yesterday and got my new rings, but in the converstation the parts guy was telling me that he rememebered a TSB that said the pick up tube & baffle had to be replaced because of the new oil manifold. I have a subscription to alldata and checked all the TSB's listed there and didn't find one. The only difference in the old and new oil manifolds that I could see was the molded in seal around the pick up tube. I'm going to go by the Stealership this morning and double check. As long as I'm where I'm at I can pull it apart again and use the anerobic sealer. Is that something that I can only get @ the dealer?


Something bothers me about what you are saying....

If you look at the old oil manifold plate you should see an oval shaped steel washer with two holes in it at each of the main bolt holes. The steel washer is cast directly into the aluminum of the plate itself. The new plate should be the same way if it is the correct one..... If the plate you got does NOT have the steel washers cast into it it is not the correct plate. The plate design and the assembly sequence was changed on the engine in 1996.

The 93/94/95 Northstar had an oil manifold plate with the 10 steel washers at the main bolt holes. The main bolts bolted down the plate and the LCC. All the mains were stud headed bolts so that the windage tray attached to the stud headed bolts with 10 nuts. That is the way your engine should have been. The steel washers were imbedded in the aluminum oil manifold plate to act as the load bearing member of the plate to distribute the load of the main bolts.

Starting with 1996 the 10 steel reinforcing washers were eliminated. The plate still looks the same with the raised area for the washers but the raised area is aluminum, not an imbedded steel washer. With the 1996 engine the windage tray changed shape slightly and the windage tray is placed directly onto the oil distribution plate and the main bolts then go thru the windage tray, the oil plate and then the LCC into the block. There is only one stud headed main bolt for 1996 as the windage tray mounts under the mains as described and not onto stud headed bolts as the 39/94/95 did.

Here's the punch line. The 96 and later plate had the oil pickup seal molded in place....so...if yours has the molded in seal I would not expect to see the steel washers imbedded in the oil manifold plate. Without the steel washers you cannot simply put the main bolts directly against the aluminum plate. It will crack and fail as the bolts exert too much load to bear directly against the aluminum plate. In the 96 engines the windage tray acts as the load bearing surface for the main bolts that replaces the steel imbedded washers. If you have a plate without the imbedded washers it is the wrong one and the only way to use it is to get the 96 windage tray and install it under the main bolts to act as the load bearing surface.

Unless...possibly someone later on released a "service" oil manifold plate that has the imbedded washers and also the later versoin of the molded in oil pickup seal....I don't remember this happening..but my memory is not perfect at all. You really should check this out... If the plate you have does not have the imbedded steel washers then don't just plop the main bolts directly against it the way the engine was assembled originally.

BeelzeBob
11-04-04, 08:15 PM
Bbob, once again you show why you are so appreciated here. Not only because of your knowledge but your patience as well.
Urban legends. Mountain medicine. It was not directed to me, and even so, I got mad...
Kudos to you.


It used to piss me off more....LOL LOL LOL I just take it as a way of asking "why can't you use the rod bearings over again...."

BeelzeBob
11-04-04, 08:27 PM
Those bearings look great!

So the bearing material is aluminum with a steel backing as compared to babbit or something of the sort?



Welll......yes, no and yes.....I think.

Yes, the bearings do look fine.

yes, the backing is steel (as is all bearings like this) but in that generation of bearing (1995) the material is still a type of "babbit" I would say. The bearing material itself is a mix of aluminum, lead, tin and other alloys...so called babbit by most people. The alloy of the bearing material changes based on the application. It needs to be hard enough to withstand the load of the oil film against it (which can be thousands of PSI due to the load of the crank and the "wedge" created in the oil film by the load) and yet soft enough to allow embedment of trash and debris so that the bearing does not fail. Any embedded debris will show as a tiny dot and surrounding circle..sort of a fisheye look...that is the debris sunken into the bearing material.

Later on, lead was eliminated from the bearing material. Lead is considered a health hazard and has been slowly eliminated from most materials due to the "fear" of lead and any possible contamination of chips and offal with lead from machining the bearings as well as exposing workers making the bearings to lead. Without lead, the bearing material is primarily aluminum. So, yes, bearings are steel backings with aluminum bearing surfaces in todays bearings but in 95 (the bearings in the picture above) those bearings still had lead bearing "babbit" material I believe.

Bearings used to be "rolled" into shape by rolling the layered material thru a set of offset rollers. Bearings today are actually machined on CNC equipment. The raw shells are set into arbors and then the bearing surface is machined to shape by high speed, CNC diamond cutters. The bearing shape inside the rod when assembled and clamped into place is NOT round. It has a distinct cammed shape that creates the oil film and loads the bearing correctly and allows for the split line relief. The CNC tooling creates this shape to the bearing surface so it is possible to put an intricate cammed surface in the bearing where it was very very difficult to roll that shape into place. Bearing technology has changed quite a bit since the 1995 engine was produced.... The CNC machining of the bearing surface also allows the elimination of the tin overplate in most cases and allows the use of aluminum alloys for the bearing surface that can be machined that could not have been rolled previously allowing for more "high performance" bearing materials to be used in passenger car engines.

Sinister Angel
11-05-04, 09:57 PM
Kinda lost me on the last part as my manufacturing knowledge is minimal at best.

Pjs
11-05-04, 11:48 PM
Something bothers me about what you are saying....

Here's the punch line. The 96 and later plate had the oil pickup seal molded in place....so...if yours has the molded in seal I would not expect to see the steel washers imbedded in the oil manifold plate. Without the steel washers you cannot simply put the main bolts directly against the aluminum plate. It will crack and fail as the bolts exert too much load to bear directly against the aluminum plate. In the 96 engines the windage tray acts as the load bearing surface for the main bolts that replaces the steel imbedded washers. If you have a plate without the imbedded washers it is the wrong one and the only way to use it is to get the 96 windage tray and install it under the main bolts to act as the load bearing surface.

Since this was first mentioned to my by the parts guy @ Bill Heard, I've been uneasy about putting it back together. I've asked a service manager @ a cad dealer in another town, his reply was "Ain't never heard of such a thing". When I went back to my local cad parts guy and asked him he had no idea either. I asked if he would check w/ the service dept and get me a definitive answer. I stopped in there an hour later and he told me the service guys say they have replaced the windage tray and oil pick up tube but there still didn't seem to be any rhyme or reason for it. Again I was stuck until Bbob posted this message. I went back to the Chev guy and explained to him what Bbob had said and then asked him what his catalog showed. There were different part #'s listed for 93-95 and 96-up. After asking him many questions for about 30 mins he finally found in the computer a note that says to use all of the new parts, he also stated that if I didn't use the new tray and oil tube that the new manifold would leak in the back right corner. I also spoke w/ another cad parts guy who said that they don't use the new windage tray and oil tube, they just bolt everything down to the new oil manifold...he says they've never had a problem doing that.
The part of this that really bothers me is that the people that are supposed to know the facts and the people that we depend on to get us the correct parts and information, namely the dealers, seem to be more clueless than anyone. I've been banging my head against a wall for 3 days waiting to put my car back together only to be run in circles. :bonkers: I finally opted to assemble everything last night only to find out today that I have to take it all back apart....again. Please excuse my frustration but I really just want to have my car on the road again.
I'm wondering if I left things the way they are, how long would it take for the manifold to crack and fail? Is this something that was discovered after running an engine for 400 hrs @ 6000 RPM and is it really critical enough to have to disassemble this thing again. :wtf:

BeelzeBob
11-06-04, 04:19 AM
If you think that you have the wrong plate in there I would never run the engine that way. I am surprised at what you are saying .... but then again I guess I am not too surprised....unfortunately.

It sounds like the older part is being serviced with the new generation of part and the callout requires the replacement of the oil manifold plate as well as the windage tray and oil pickup. If that is indeed the case then I would definitely get the correct parts. I have serious misgivings about assembling it with the incorrect parts. I am surprised that the plate didn't crack when you assembled it if it is the version without the imbedded steel washers.....

If I had known you were springing for a new oil manifold plate I would have offered up another option...one that you can still use. Take you old plate and reuse it. Take the time to use a sharp tool and just dig/scrape the old, molded in silicone beaded seals out of the plate. You do not need to get the grooves that the molded beads are in perfectly clean but you do need to get most of the old seal out of it. Clean the plate up meticulously for grease and oil. Spray it with a good degreaser when you are finished to make sure that the plate is clean. Clean the mating surface of the LCC. Apply a THIN bead of RTV to the old seal grooves and assemble the plate to the LCC. Tension the main bolts and forget about it. The formed in place gasket with the RTV will make a perfect seal that you can forget about forever. Use a high quality RTV made for high temp automotive use such as the copper colored, high temp RTV. The challenge is to apply just a small bead...about twice as high a bead as the original molded seal bead was and to get the surfaces squeeky clean. The other challenge, which is easy in this case, is to wait for 24 hours for the RTV to cure before putting oil in the engine. The RTV must cure for 24 hours before seeing oil or it will not cure correctly...which is one main reason that gluing things together with RTV gets a bad rap....people don't wait for it to cure before "using" it. You can do the same thing with the oil pan. Take the molded seal out, fill the groove with RTV and assemble. Just make sure that both the seal groove and the mating surface are perfectly clean and the RTV makes a permanent joint. Engines that are "glued together" at the factory with RTV have, by far, the best oil leak history in the field. No comparison to "gaskets" and "seals". That is what I would do......

Pjs
11-06-04, 09:54 AM
If you think that you have the wrong plate in there I would never run the engine that way. I am surprised at what you are saying .... but then again I guess I am not too surprised....unfortunately.

It sounds like the older part is being serviced with the new generation of part and the callout requires the replacement of the oil manifold plate as well as the windage tray and oil pickup. If that is indeed the case then I would definitely get the correct parts. I have serious misgivings about assembling it with the incorrect parts. I am surprised that the plate didn't crack when you assembled it if it is the version without the imbedded steel washers.....


GM is only listing one plate in their catalog p/n 12581288. The really bad part is that they still list the original p/n's for the oil tube & windage tray to use with the new manifold. Like I said, It took me asking a whole bunch of questions and making the parts guy go through his catalog till he found the update for the oil tube p/n 3546580 and windage tray p/n 3544725. So basically the dealer is willing to send out incorrect parts to it's customers without a second thought. I just got off the phone w/ my local dealer and he's got both in stock, I *WILL* be installing both today.



If I had known you were springing for a new oil manifold plate I would have offered up another option...one that you can still use. Take you old plate and reuse it.

That exact thought had crossed my mind, however the "guys" @ the dealership told me that wouldn't work. I personally thought they were wrong but had to give them the benefit of the doubt as I thought they knew what they were talking about. At this point I've already spent $125 for a new plate but I'll hold onto my old one, just in case.

Pjs
11-06-04, 01:04 PM
I have serious misgivings about assembling it with the incorrect parts. I am surprised that the plate didn't crack when you assembled it if it is the version without the imbedded steel washers.....


I just got back from the stealership...again, this is getting to be a bad habit. I had the parts guy bring out the new tray and tube as well as a new manifold. The raised area that you had talked about on the new manifold apparently has been done away with and the plate is smooth all the way across. This leads me to think thats why the plate didn't crack. I'll be on my way to put it back together right this time, and hopefully, barring any other incidents I'll be back on the road tomorrow.
Bbob, I appreciate your help in getting all this sorted out :)

BeelzeBob
11-07-04, 01:47 AM
The RTV trick will not work unless you scrape out all the old molded in silicon beads. That is probably why they said it would not work. RTV is not designed to work in a "zero clearance" joint...it has to have a groove to fill...that is why you need to scrape out the old, molded in place silicon beads to open up the groove for the RTV. This is actually the way the engine is being built "today" as the 2005 Northstars are sealed on the lower end with 100% RTV.....

I am going to have to go find out what the deal is with the service parts for the oil manifold plate on the older engines. Sounds like something has been changed that I didn't know about.

dkozloski
11-07-04, 02:23 PM
bbobynski, is GM like the aircraft manufacturers? There are a bunch of junior engineers in every department and one or two gurus. Every Monday morning the juniors are lined up at the doors of the gurus with a problem that needs solving. If it is, my money is that you are one of the oracles visited.

Pjs
11-07-04, 06:27 PM
I am going to have to go find out what the deal is with the service parts for the oil manifold plate on the older engines. Sounds like something has been changed that I didn't know about.

I installed the new windage tray and when I was going to bolt up the new oil tube I ran into a problem. The new tube, although fits the molded seal, it doesn't line up with the main bolt hole. The old one will still work installing it on the main bolt stud. I'm assuming that I don't need to use the O-ring on the pick up tube in conjunction with the molded in seal on the manifold.

Rob Benham
11-08-04, 04:02 AM
Great thread guys. It's a little different to the 50's in the UK when dealers would keep American cars going by getting some of the ‘ovality' out of the crank with a leather dog lead and valve grinding paste.

RB 94 SLS

Pjs
11-19-04, 04:39 PM
The down side to the extra crush is that the bearing is put into such a high compression when assembled that it actually takes a slight "set" if the engine is run and the bearing subjected to high loads and high temperatures. It happens, trust me. Every time I have ever seen a Northstar dyno engine taken apart and the rod bearings reused the engine would eventually fail a rod bearing. This did not have to happen too many times to teach us that you do not reuse the high crush rod bearings over again if the rod is taken apart. I saw this with my own eyes, have measured the bearings and know that it happens.


This was a handy tidbit of info. Now that I got my timesert kit for the main bolts, I quickly realized last night once I saw the drill fixture that I'm going to have to pull out the crank. I was really hoping that I could get away with doing the timeserts with the crank in. I've got a std set of rod bearings on order @ the cad dealer. Are there any tricks to the rod bearings that I should be aware of before I do this? I've been trying to get my car back together for 3 wks now and every week I keep thinking...next week it will run, only to run into other problems...so if all goes well...maybe it will run next week..keep your fingers crossed.

BeelzeBob
11-19-04, 06:53 PM
There is nothing special to do to the rod bearings when you install them. Just line up the tangs and put the caps on. You will want to mark the caps carefully before you take them off of course. The rods in your motor have the cracked caps...the parting line of the cap is a fractured surface so it will obviously look....er...ah....broken and rough. That is good as it assures a perfect alignment of the cap onto the rod when it is reinstalled.

If you are going to pull the crank then you have to completely dissassemble the timing drive and such. Put the engine to TDC #1 before you tear the timing drive down so that you won't worry about bending any valves or anything when reassembling. When you put the engine to TDC likely the timing marks on the primary drive will not line up. Do not be dismayed. There is an uneven drive ratio on the primary drive so the marks only line up again every seven revolutions of the crank and even then the cam sprocket marks will not line up correctly. The whole series of marks on the sprockets will only come back into alignment every 14 revolutions of the crank. Not to worry. Just take the sprockets off and when reassembling at TDC #1 put the marks into alignment and it will go together fine.

I still cannot figure how you stripped a main bolt. That is very very unusual no matter how many times the LCC comes apart. Are you positive that the bolts are the correct length with the replacement oil manifold plate and such??

Pjs
11-19-04, 11:07 PM
If you are going to pull the crank then you have to completely dissassemble the timing drive and such. Put the engine to TDC #1 before you tear the timing drive down so that you won't worry about bending any valves or anything when reassembling. When you put the engine to TDC likely the timing marks on the primary drive will not line up. Do not be dismayed. There is an uneven drive ratio on the primary drive so the marks only line up again every seven revolutions of the crank and even then the cam sprocket marks will not line up correctly. The whole series of marks on the sprockets will only come back into alignment every 14 revolutions of the crank. Not to worry. Just take the sprockets off and when reassembling at TDC #1 put the marks into alignment and it will go together fine.


I have a couple questions about that. While looking through the manual last night I found where you can change the primary tensioner and guide without having to reset the entire timing system. It looks to me that it's possible to put #1 to TDC and then remove the tensioner and guide which looks like it would give me enough slack in the primary chain to take it off the gear which would allow the crank to come out without disturbing the rest of the timing components. I don't know if this has come up before, but it's an idea I'd like to try unless you advise against it. The other thing I need to know is in the event I do have to pull the other chains, I don't have access to the J tool for keeping tension on the chains that is shown in the manual. Is that really necessary for reassembly when I have access to the whole system?

These might sound like elementary questions, but since first taking this engine apart I've become very aware of a statement you made in post awhile back that the N* is easy to work on, but don't treat it like a conventional engine.



I still cannot figure how you stripped a main bolt. That is very very unusual no matter how many times the LCC comes apart. Are you positive that the bolts are the correct length with the replacement oil manifold plate and such??

Given the age and milage of the engine I'm not really all that surprised. Actually before I even took it apart the first time I was afraid this was going to happen. I did take great care when disassembling the first time, I broke the bolts loose with a ratchet instead of using the impact. I kept all the bolts in order so they went back into the same holes. Upon removing them the first time I noticed a couple bolts had a stray thread here and there but nothing that really stood out unless you were looking for it. The new manifold that I bought has no raised area like you described (in place of the steel washers), the whole surface is completely flat. On one of my trips to the dealer I had them pull another manifold for me to look at and they are all flat.
I have no way to accurately measure the depth of the holes but I reckon it's possible because there was nothing under the bolt that perhaps they bottomed out in the block. When I disassembled the second time to install the new windage tray, one bolt in particular was rough coming out. It was the bolt that the oil pick up tube leg goes on. When I tried to thread it back in, I had a light coating of oil on the bolt, but it was really rough going in. I threaded it down probably about 1/2 way before I put a wrench to it. I never even got the 15 ft/lbs before it let loose. When I pulled it out last night, all of the threads were stuck to the bolt. Although thats the only one that really stripped, there are other holes that the threads look pretty rough in. I could probably get away with only inserting 2 holes, but at this stage I think its prudent to do all the holes, at least for my piece of mind.
Who knows, I may have been able to run the engine the way it was before I installed the new windage tray without a problem but in the back of my mind I'm convinced that bolt would have failed under load sometime in the future. I do find it somewhat disturbing that of the 3 cadillac dealers I talked with had no idea about any of this and had told me that they install the new plate and use the old windage tray, so far apparently they haven't had one come back yet. The other side of that is that I'm sure most of those people don't push their engines like I do.
I am a little confused about the new oil pick up tube as well. It doesn't seem to line up like it should, the old one however looks like it will work fine except that it has a groove for an o-ring, where as the new one does not because of the molded-in seal on the manifold. So I'm not sure if they are not compatible, or can I use the old tube with an o-ring in conjunction w/ the molded seal?

I really appreciate all the input all y'all have given me in trying to get this thing repaired correctly....And Bbob, I don't care what anyone says..You are THE man :thumbsup:

BeelzeBob
11-20-04, 12:40 AM
If you have the engine apart there is no need for any special tools to do the timing chains and tensioners. If it is apart you just reset the tensioner before reassembly. It is self adjusting so there is nothing to worry about. The special tool to hold it is just for when the engine is in the car and you need to remove the cam chain and do not want the tensioner to move. This is not your case.

You will spend more time trying to manipulate the primary chain around to remove the crank than just taking the timing drive apart and putting it back together from scratch. Just rip it apart, lay out the pieces and it goes back toqether quite easily. Everything is marked that has to go a certain way or in a certain place so it is quite error proofed. It is just easier if you take it apart with the crank at #1 TDC so that the engine is timed correctly for reassembly without having to turn any cams or anything. Otherwise, you risk bending some valves if you start with the engine in a random position and start trying to move the crank and cams to #1 TDC for assembly. Put it there before removing the timing drive and crank and then put the crank back in at the same position and it will be very simple to build up the drive from scratch. Much easier than trying to work around it otherwise.