: tight northstar cam chain



northstarcamchain
04-21-12, 05:58 PM
my 97 deville with 79k easy miles on it has cam chains so tight they make noise rubbing against the dampers. I believe this is due to one or more bad lobes on the cam or cams, which cause the lifter/lifters to not spin as they should, causing the drag on the cam shaft and cam chain(s).

Has anyone run into this, and does anyone have a line on reground cams or low mileage used ones?

I could hear a noise coming from the center of the exhaust side fo the front head, in addition to the cam chain noise, so I pulled the cam shaft and sure enough, there was a little bald spot worn in the chrome of the flat lifter face, right where the exhaust cam lobe on #6 piston cam to push the lifter down. So this lifter had stopped spinning, and worn a spot in the chrome on the flat lifter face, and the lifter was just dragging across this bare spot. And you could feel it and hear it when you revved the engine a little.

So I replaced all chain dampers, oil pump, lifters, and valve seals. Still have the same cam chain noise, but not the noise coming from the center of the front head due to the bad lifter, since all lifters are new now. But one or more lifters are not spinning in the bores as they should, causing the cam(s) to drag, causing cam chain to drag against the shoes. ON flat lifter engines, all the lifter have to spin for the engine to run right. If they dont, they will wear out.

the cams look like new, but must have one or more bad lobes causing the lifter(s) to not spin. Not all the lifters and lobes, but 1 or more.
I believe this is heat related. since the water pump tensioner bearing locked up a while back and shredded the belt. I shut off the engine as soon as the chime came on at 250 degrees, and pulled into a gas station and got towed home.
(Also it rained after I pulled the cam covers off, and the cam lobes rusted from condensation. I sanded the rust off the lobes with 240 grit sandpaper and covered the lobes with moly grease. But this was after the teardown due to cam chain noise. I'm sure the sand paper doesnt help the smooth finish of the lobes, but new cams dont have a smooth lobe finish to begin with.)

What do you think, Mr. AJXTCMAN?

I am an ex gm mechanic, and have owned many cadillacs and lincolns. I have little experience with flat lifters and single row cam chains. The chains & sprockets have no wear on them at all. the tensioners are right at the beginning of their travel. I know chains and sprockets well, since I have ridden dirt bikes all my life.

Submariner409
04-21-12, 07:01 PM
............your engine has hydraulic cam chain tensioners, on all three chains, to keep the effort side of the chains TIGHT: No timing slop. The cam lobes and lifters have nothing to do with that. The lobes/lifters wear exactly as they would in any flat-tappet engine: wear proceeds until the case hardening of the cam or follower bucket is worn to the point at which one microscopic groove starts, causing the follower (lifter) to stop rotating and then the cam busily eats into the follower face.

From your wear description you're in the market for 4 new cams and 32 followers - $1400 +++.

You might want to search for threads which discuss the HD fleet and marine engine oils which have a higher ZDDP level than today's SM/SN "starburst" oils. They're available in several large brand names in a 10W-30 viscosity rating. That (ZDDP and its lack thereof) is the cause of your cam lobe/follower face wear, not chain tension.

northstarcamchain
04-21-12, 10:42 PM
yes, of course. the chain tension is just what is causing the loud chain noise, from being too tight against the dampers and guides. It had nothing to do with the cause of the problem, which is worn cam lobe(s) and lifters. I already bought the new lifters, now I need some cams.

89falcon
04-21-12, 11:01 PM
yes, of course. the chain tension is just what is causing the loud chain noise, from being too tight against the dampers and guides. It had nothing to do with the cause of the problem, which is worn cam lobe(s) and lifters. I already bought the new lifters, now I need some cams.

Maybe you have a worn guide or two....I imagine it gets loud if it ever gets to metal on chain....

Ranger
04-22-12, 12:55 AM
Those chain tensioner shoes are supposed to be good for the life of the engine.

Faded Crest
04-22-12, 01:00 AM
Those chain tensioner shoes are supposed to be good for the life of the engine.

Excuse the picture being upside down, but you can see my timing chain tensioner was completely extended and worn all the way through the shoe and ever so slightly into the metal at 104k. But my Cam chain tensioners are in great shape. I wish I had taken a picture of it removed so you could see better.

http://i1218.photobucket.com/albums/dd407/thejumpsuitman/102_0670.jpg

Submariner409
04-22-12, 10:31 AM
F C, You beat me to it: If the OP has more than a slight timing chain whirrrrrrrr........... then one or more tensioner slippers are worn and the chain(s) are eating into the tensioner shoes themselves.

Your picture is classic, and not only for this particular Cadillac engine. ANY OHC engine with chains and tensioners has the same eventual slipper/guide wear problem.

(and, to dredge up an old thread/post which said that engine oil analysis was unnecessary for a passenger car, I would like to state that oil analysis would have found the elevated iron (steel) levels in the oil from your engine with the worn slipper..........or in the OP's engine with worn cam follower buckets.)

Ranger
04-22-12, 11:56 AM
WOW! That IS worn bad, but something is not normal there. Why is one side worn that bad and the other is not? There is something else going on there.

northstarcamchain
04-22-12, 01:16 PM
you guys dont get it. I have already replaced all shoes and guides and lower tensioner. they are brand new. the chain did eat down into the plastic on the original ones, the shoes and lower tensioner which has the shoe on the tensioner itself, -- two grooves where the links ride on the plastic. The guides had very little grooving. the cam chain noise is from the tight cam chain hitting the new plastic shoes. you can hear every link hit the plastic. chain is too tight due to lifters not spinning due to worn cam lobes.

now i need a line on some good low mileage used cams.

----------

I guess I didnt describe my repairs well enough. I too thought to begin with that it was the dampers making the noise. So I replaced all dampers and guides and lower tensioner that has shoe on it for the primary chain. new oil pump too. Started it up -- same noise. (I had checked the intermediate sprocket bushing but no wear at all). So then I pulled the cam covers (which I didnt want to do to begin with) and pulled the exhaust cam on the front (left) head and saw the lifter with the little spot in the face where the chrome wore off from the cam lobe. So I put in 32 new lifters (and 32 new valve stem seals since it had started using oil since it got to 250 degrees twice and fried the original valve seals). Started it up and guess what -- the lifter had gotten quiet but still same cam chain noise. Only thing to do now is replace cams.

northstarcamchain
04-22-12, 06:58 PM
This problem with the big flat lifters and cams is the reason they went to roller lifters in northstars from 2000 on. and the price on them is 1/3 the price of the flat lifters and cams.

when the lifters dont rotate (as they should), it is hard for the cam lobe to push the lifter down against the valve stem. this is what causes the resistance to the cams rotating, which pulls on the chain, which causes the chain to be too tight, which causes the cam chain noise when it rides on the chain dampers. the new dampers are already getting grooves worn in them, and the engine has only been run twice for 30 minutes at a time with the new dampers in it. also, the noise is the loudest when you first start the engine, before the oil gets to the chain and dampers from the camshaft spill onto the lifters. and the oil is really flowing with the new oil pump, even at idle.

northstarcamchain
04-23-12, 12:19 AM
that is some picture. Did you check for termites?

That is why they put a fourplex primary chain on the new vvt engines, instead of the bicycle chain like they have on the old northstars. the secondary chains are still single row though. are they are having trouble with it. even on new engines.

Faded Crest
04-23-12, 12:26 AM
With that kind of wear on the primary chain at 104k, it really makes me wonder what others look like with more miles.

Ranger
04-23-12, 12:38 AM
That is why I said there is something else going on there. THAT is not normal 104K wear.

Faded Crest
04-23-12, 12:41 AM
That is why I said there is something else going on there. THAT is not normal 104K wear.

Like what? faulty tensioner? Burr on the chain?

Ranger
04-23-12, 10:59 AM
:noidea: I'm at a loss on that. All I know is that those shoes should go 4 or 5 times that mileage without wearing through like that. It would appear to me that that tensioner was applying excessive tension. Perhaps it was worked on before and installed wrong?

drewsdeville
04-23-12, 11:06 AM
(and, to dredge up an old thread/post which said that engine oil analysis was unnecessary for a passenger car, I would like to state that oil analysis would have found the elevated iron (steel) levels in the oil from your engine with the worn slipper..........or in the OP's engine with worn cam follower buckets.)

...and wouldn't have changed a thing. Oil analysis would have detected the wear, but wouldn't have fixed it, and the OP would still be dealing with the problem at some point.

Detection isn't the difficult part - the problem is quite obvious. His question is about fixing it. Blackstone will not fix his engine.

Faded Crest
04-23-12, 01:04 PM
:noidea: I'm at a loss on that. All I know is that those shoes should go 4 or 5 times that mileage without wearing through like that. It would appear to me that that tensioner was applying excessive tension. Perhaps it was worked on before and installed wrong?

That was my thought. Faulty tensioner with too much outward pressure. A disaster might have been looming had I not discovered this... Maybe a blown head gasket was a blessing in disguise.

CadillacLuke24
04-23-12, 03:22 PM
:yeah: Being an interference engine, had the timing chain broke or lost tension, you'd have valves hitting pistons....

KA-BOOM!!

Submariner409
04-23-12, 06:02 PM
...and wouldn't have changed a thing. Oil analysis would have detected the wear, but wouldn't have fixed it, and the OP would still be dealing with the problem at some point. Detection isn't the difficult part - the problem is quite obvious. His question is about fixing it. Blackstone will not fix his engine.

Well, Duh !!!! Of course Blackstone can't fix the thing over the Internet and no one has ever said they could - but they can tell you there appears to be an accelerated wear problem, so start looking..........

Armed with a report of elevated iron/steel level in the oil and a symptom of exaggerated cam chain whine might allow a wrencher to put 2 & 2 together.

Faded Crest
04-23-12, 06:18 PM
Actually an oil analysis would have let me know something was going on with that tensioner too, once it started eating down into the metal.

drewsdeville
04-23-12, 07:31 PM
Well, Duh !!!! Of course Blackstone can't fix the thing over the Internet and no one has ever said they could - but they can tell you there appears to be an accelerated wear problem, so start looking..........


I guess...if you have that kind of time. Personally, I wouldn't rip apart my engine looking/hoping to come across a just-beginning problem because of elevated material in an oil analysis. I'd probably wait until there were more identifiable symptoms, like the noise the OP witnessed, which will appear whether I get an oil analysis or not.

northstarcamchain
05-01-12, 10:18 PM
RESOLUTION TO TIGHT CAM CHAIN

I knew that the tight cam chain was caused by not all the lifters rotating, just some of them. So I spoke to a cam shaft guy who regrinds northstar cams for racing applications. He said that northstar cams are not cut at an angle, like the tech article i read said, but are flat, and the rotation is caused by the offset.
So I was examining the offset on my engine, and sure enough, the round part of the cam lobe opposite the high point only goes halfway across, so it only contacts the lifter on one side, causing it to rotate. I then started examining the lifters that did not rotate, to see why they didnt. and I found out why -- the valve springs were so sacked out that I could push them down with my hand. this caused the cam to just slide across the lifter, instead of spinning it, since there was not enough pressure from the spring to get any traction between the cam and the lifter face.

This is an old problem that Cadillac has had for over 50 years. Sorry quality valve springs that sack out whenever your engine overheats. I found this out in 1976 when my eldorado with a 500 c.i. engine overheated one time due to stuck thermostat. One valve spring sacked out so bad the engine missed on that cylinder. so I took it to the cadillac dealer and told them to do a valve job. They charged me $1100 for a valve job and didnt do one thing to the engine. I had to replace the bad spring in my driveway myself after paying them for doing nothing. so I will never go to a cadillac dealer for service.

Turns out 4 to 5 valve springs on each head were so sacked out that you could push them down with your hand. This was caused by overheating 2 times to 250 degrees for a short time.

So I am replacing all 32 valve springs. This will solve the problem.

Any cadillac engine that has overheated probably has one or more weak valve springs.

Submariner409
05-02-12, 11:55 AM
THAT is good info ^^^

It's always a good idea to check valve springs for tension at installed and valve lift height. There's a special tool/gauge for the job - any engine rebuild shop has one. As you pointed out, cheap insurance.

Faded Crest
05-02-12, 12:17 PM
Glad you got it fixed, but I doubt it is a very common thing for valve springs to get weak after a couple times running hot. 250 degrees isn't even really considered to be all that hot on a Northstar... I have gotten engines very hot in the past and never had any kind of problem like that after. Years ago I had a '75 Fleetwood with a 500 that I got extremely hot because there was no safe place to stop for a mile or two... I was actually pretty worried about it, but after I unstuck the thermostat there were no ill effects at all. Done that more than once, I am ashamed to say, but have never had any kind of head problems afterward.

89falcon
05-02-12, 02:22 PM
Glad you got it fixed, but I doubt it is a very common thing for valve springs to get weak after a couple times running hot. 250 degrees isn't even really considered to be all that hot on a Northstar... I have gotten engines very hot in the past and never had any kind of problem like that after. Years ago I had a '75 Fleetwood with a 500 that I got extremely hot because there was no safe place to stop for a mile or two... I was actually pretty worried about it, but after I unstuck the thermostat there were no ill effects at all. Done that more than once, I am ashamed to say, but have never had any kind of head problems afterward.

I'd think the exhaust valve springs would get pretty hot anyway...and for it to be more of a function of how hard the car has been run.... The valves springs probably don't get much cooling from the coolant....more from oil....which is running hotter than the coolant anyway.

Good post though! never thought to check the springs, and really don't want to pull all 16 from each head!

northstarcamchain
05-23-12, 12:21 AM
NO MORE CAM CHAIN NOISE -- VALVE SPRINGS WERE OK.

I was wrong about the valve springs. My valve springs checked out good. The problem was that the primary chain tensioner was still tight because I never released the tension off it after I replaced the lifter that was causing the exhaust cam to drag. I removed and replaced the secondary tensioners so that I could remove the cams, but never removed the new primary tensioner that I installed before I pulled the cam covers. duh!

Also, I talked to a head rebuilder who does a lot of northstar heads. A lot of them are not worth rebuilding because when they get hot they warp. the middle of the head bows up. the ends of the head stay down. so the bearing surface under the center cylinders where the cam rests push up, and the end of the cam locks up against the cam caps on the end of the head.
He has seen a lot of grooved cam caps and ruined cams, locked completed up. Even if the head is milled, the cam bearing surfaces dont line up.l
So if you have a cam that is dragging just a little on the end cap away from the chain, the thing to do is not to sand on the cap, but to sand a little off the center cam bearing surface underneath the cam on the middle bearings. Plastigauge them. This will keep the cam from pushing up against the caps on the end of the head.

dkozloski
05-23-12, 02:25 AM
Shave the parting surface of the caps and then line bore the heads on a Tobin-Arp line boring machine.