: Spun bearings in my '94 STS



Spyder
08-30-04, 12:43 AM
So the verdict is in...looks like its a spun main bearing on my '94 STS. The plan is to pull the engine and then the crank, grind the crank and put new bearings in it. My step brother's got a shop and he's offered to help me to do the work for beer money, all I have to do is pay for parts and machine work. Is it a feasible project or does anyone here have any ideas that would be helpful? Are bearings for the N* available? Private Message me with any advice, or I'll check back in this thread in a day or two. Thanks a bunch! So far this forum has been incredibly helpful, hopefully it'll stay that way!

James

Geno Castellano
08-30-04, 03:55 PM
How on earth did you spin a main bearing? That's very very uncommon with a Northstar... in fact, I don't remember ever seeing it unless someone ran it without oil and then the rods usually go first.

Grinding the crank is not a good idea. The fillets of the main and rod journals are rolled with a very high residual compressive stress. Quite often when you start grinding into the journal the residual compressive stress starts to relieve itself and the crank ends up very crooked. Unless you have special tooling (very special tooling) you cannot re-roll the fillets. Most cranks that have fillets rolled like that for superior strength are considered scrap if they are dinged by a bearing failure. Besides, I don't think that there are any undersized main bearings serviced for the crank. I would look for a new crank or a replacement/parts engine.

Spyder
08-30-04, 09:56 PM
It happened about 6 miles after I had the local Wal-Mart change the oil...I havn't looked at it myself, but both the shop I took it to and my step brother told me that its a spun bearing. I shifted from 2nd to third with my foot off of the accelerator at about 5500 rpm, and it instantly started making a whole lot of noise and lost all its power. The noise is a random but always there banging...sounds like a hammer on the inside of the engine...not a steady sound, but it changes speeds without the speed of the engine changing...and the power was drastically reduced. It still starts right up and the temp. doesn't go up at all and it still runs really smooth, just incredibly loud. What else could it be if not the bearing? Thanks Geno, I've been stuck driving a '78 Diesel Olds Royale until I can get my caddy fixed.

Just talked to him on the phone to verify some things...says he hasn't yet pulled the pan and won't have time to do it for a week or two, but did have the timing cover off and valve cover off and went around with a stethoscope and the sounds definately in the bottom end.

rollman
09-03-04, 06:49 PM
5500 rpms . :tisk:

Aurora By Olds
09-03-04, 07:44 PM
5500 rpms . :tisk:
Whats wrong with 5500 r's??
Personally I would take a good look at what wally world could have done to it. Seems odd it would happen RIGHT after the oil change...

dkozloski
09-03-04, 08:55 PM
If a main bearing is spun you are in for a very specialized repair of the main bearing bore. If the damage is slight it can be repaired by shaving off the caps and line boring the crankcase but if the damage is severe it will require a welding repair that is very, very, tricky followed by line boring. That combined with the damaged crank just about dictates a new engine. This is not a job for a dirt-floor garage or a hobbyist.

eldorado1
09-03-04, 10:25 PM
After you add up all the cost of machine work, bearings, new crank, etc... I think it would be worth your while to put in a new (used) engine. $700 will typically get you a 60,000mi used engine, just swap your parts onto it.

Geno Castellano
09-04-04, 12:20 AM
If a main bearing is spun you are in for a very specialized repair of the main bearing bore. If the damage is slight it can be repaired by shaving off the caps and line boring the crankcase but if the damage is severe it will require a welding repair that is very, very, tricky followed by line boring. That combined with the damaged crank just about dictates a new engine. This is not a job for a dirt-floor garage or a hobbyist.


Not disagreeing with you but understand that the Northstar engine does not have "main caps" per se. The engine is a bed plate construction in that the lower crank case, main caps and such are in one piece and the block splits at the crank center line. If a main bearing bore is damaged it is very involved to take material off the mating surface of the lower crankcase and remachine the main bores much as you describe. I know of few machine shops that would be able to do this correctly and get the mains round correctly. It's not easy with the bed plate design of the engine.

Geno Castellano
09-04-04, 12:27 AM
5500 RPM? That's nothing.. The engine can run there all day and night for a long time with no problems. Something had to be wrong or happen at the "oil change" you describe. My suspicion is that something else happened and that the problem is not a main bearing.

If something lube related happened at the "oil change" it is more likely a rod bearing than a main. The rods always go first in the case of a lube problem. Not to say that the mains aren't hurt too - but likely the problem making the noise is a rod.

Are you sure the engine had oil pressure after the oil change? The 93/93/95 engines could (rarely) stick the oil pressure relief valve due to debris and fail to prime the pump after a hot restart or on a cold start. In which case there would be no oil pressure. It would really be a very chance, random occurance, really nothing to do with the work done on the engine. But, you should have had an oil pressure warning light at startup and noticed the lifter clatter and such. Is the oil pressure warning light working? Does it have oil pressure? Take the oil fill cap off and look inside the engine when it is idling. You can see the front cam bearing caps and if there is oil pressure you will see oil oozing from around the cap between the cap and the cam bearing. If it's dry and no oil is visible coming off the bearing cap interface then chances are there was no oil pressure and the engine is shot.

dkozloski
09-04-04, 01:56 AM
Geno, thanks for the info on the engine design. I was not aware of this. I was speaking from my experience managing an aircraft engine overhaul shop for over ten years. Opposed aircraft engines are also split at the crankshaft centerline and are repaired by lapping at the parting surfaces and then line boring for bearing bore repairs or in the case of severe damage some very judicious welding. The large aircraft machine shops are very skilled in this type of work. Arnold Nickson in Santa Maria, California does work of this type that is beyond description.

Spyder
09-04-04, 04:03 AM
The oil pressure light never came on and there wasn't any lifter noise prior to the knocking, at least none that I heard with the windows up and radio on...Unfortunately, I don't even have the car at my place anymore, I had it towed to a shop about an hour north of me. I've been looking around for a new used engine for the car, and the cheapest I've found was $1,900 for one with 66K miles. That seems a bit steep to me for a used engine without any of the accessories. The going price out here in California that I've been finding is around twenty five hundred, and they all, so far, have had upwards of 60 and seventy thousand miles on them. I figure if I'm going to put a used engine in, I'll have to timesert it as well, which adds to the cost. If I didn't still owe money on the damned car, I'd just be done with the sob, but I have to keep making payments on it and paying the full coverage insurance for a useless pile. I love the car, but am getting very frustrated with this problem. Any ideas on where to find a cheaper or lower mileage engine would be hugely appreciated!
Thanks a bunch for all the help...

Ranger
09-04-04, 12:48 PM
I have no idea what year this engine is or what he wants for it but her'e's your first lead.
http://caddyinfo.ipbhost.com/index.php?showtopic=3167

eldorado1
09-04-04, 07:33 PM
Yeehaw! There's some pricey engines in CA! Cheapest vin9's I found via car-part.com:

1993
Engine
Cadillac Eldorado (4.6L), VIN "9- O.D. 18721 $1750 Riteway Auto Parts - RPN USA-CA(Fontana) Quote 1-800-852-8733 Insurance-Quote

1993
Engine
Cadillac Seville 17064 $1750 Standard Auto Recycling USA-CA(Chula-Vista) Quote 1-619-426-1166 Insurance-Quote

There's a complete 93 drivetrain on ebay right now for $300, but it's 130k, and you just want the engine :p

Spyder
09-04-04, 08:55 PM
Yea, I saw that three hundred dollar one...was tempted to get that, put it in, sell the car and buy a '96 STS, but I really like the vinyl top and the wheels on mine and havn't seen any others like it :(
The Eldorado engine will work as long as it is a 9-vin engine from an ETC?