1988 Olds 3800 Vin C engine rattle - Fixed

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Hi Folks
This is a post to a engine rattle problem that I have fixed on my 1988
Olds 98 with 3800 Vin code C. Here is a description of the problem as posted about a year ago.
I have a 1988 Olds 98, with a 3800 Vin C engine, 195000 Kms on the odometer, that has an engine rattle that I have been chasing for over a year and it's driving me nuts. The rattle is only at idle and is especially pronounced when in drive or reverse. It comes and goes with the slightest increase in engine speed. It sounds like nuts and bolts rattling in a can. It's not rod knock due to low oil presure as I know what that sounds like. It also seems to be a bit worse when the engine has been warmed up. Driving at normal speeds it's totally gone and the engine has not yet fallen apart since this appeared 15000 kms ago.
Here is a bit of history of what has been done to this engine:
150000 kms Replaced heads due to burned exhaust valves cyl 1 and 6. Also replaced timing chain, gears and the tensioner with aftermarket parts. I was not really all that impressed with the replacement parts but changed them any way. The originals looked quite good.
180000 kms Rattle begins to show up and slowly gets worse with time.
195000 kms Compression is 160 on all cylinders. Replaced water pump and serpentine belt tensioner wheel, Harmonic balancer is in great shape. Removed serpentine belt and ran the engine in drive, rattle is still present Removed oil pan and checked for loose/cracked baffles, all was ok Checked tranny flex plate for cracks, etc, it is also ok. Checked catalytic converter for loose shields, etc, it is also ok.
The rattle seems to be coming from the upper part of the engine and more
from the driver side. I have used a stethoscope to locate it, but can't seems to pin point it a specific area. It does however seem to be quite
strong on the left side (drivers) of engine, possibly in the area of the
exhaust crossover pipe. Can't find any loose parts in this area that would rattle.
I have a few ideas but need some feed back before taking apart the engine to check these:
1. Possible worn timing chain tensioner (yeh, the replaced one) and the chain is flopping around.
2. Some loose internal baffle in the catalytic converter.
3. I don't remember any more, but I beleive the intake manifold gasket consists of a sheet metal baffle. Could this have cracked/broken and is vibrating al low rpm. I did have to plug a leak in the intake manifold area with silicone.
I finally descided to open the timing chain area, and found that the aftermarket chain and tensioner (damper) had more wear and slack after 45,000 kms than the original GM parts after 150,000kms. Since I had saved my old GM original timimg chain and steel gears and in my unexpert opinion they still looked damm good, I descided to re-use them again. Some might say this was not wise, but I was in no mood to spend any more than I had too. I also installed the following new GM parts: 1. Damper (tensioner) 25535668 2. Cam buttton 25532434 3. Cam shaft timimg magnet 25530386
I fired it up and guess what, it now purrs like a kitten. Engine does not rattle and has the soothest idle that it's ever had.
This problem has been reported on a couple of other posts in this NG. Hopefully this info will help some one else. See also this link which talks about the same problem: www.cloyes.com/pdftips/tip9.html
Take care Ted M Canada
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<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> Hi Folks <p>This is a post to a engine rattle problem that I have fixed on my 1988Olds 98 with 3800 Vin code C.&nbsp; Here is a description of the problem as posted about a year ago. <p><i>I have a 1988 Olds 98, with a 3800 Vin C engine, 195000 Kms on the</i> <br><i>odometer, that has an engine rattle that I have been chasing forover a</i> <br><i>year and it's driving me nuts.&nbsp; The rattle is only at idleand is</i> <br><i>especially pronounced when in drive or reverse. It comes and goeswith</i> <br><i>the slightest increase in engine speed. It sounds like nuts andbolts</i> <br><i>rattling in a can. It's not rod knock due to low oil presure asI know</i> <br><i>what that sounds like.&nbsp; It also seems to be a bit worse whenthe engine</i> <br><i>has been warmed up. Driving at normal speeds it's totally gone andthe</i> <br><i>engine has not yet fallen apart since this appeared 15000 kms ago.</i><i></i> <p><i>Here is a bit of history of what has been done to this engine:</i><i></i> <p><i>150000 kms</i> <br><i>Replaced heads due to burned exhaust valves cyl 1 and 6.</i> <br><i>Also replaced timing chain, gears and the tensioner with aftermarket</i> <br><i>parts. I was not really all that impressed with the replacementparts</i> <br><i>but changed them any way. The originals looked quite good.</i><i></i> <p><i>180000 kms</i> <br><i>Rattle begins to show up and slowly gets worse with time.</i><i></i> <p><i>195000 kms</i> <br><i>Compression is 160 on all cylinders.</i> <br><i>Replaced water pump and serpentine belt tensioner wheel,</i> <br><i>Harmonic balancer is in great shape.</i> <br><i>Removed serpentine belt and ran the engine in drive, rattle is still</i><br><i>present</i> <br><i>Removed oil pan and checked for loose/cracked baffles, all was ok</i> <br><i>Checked tranny flex plate for cracks, etc, it is also ok.</i> <br><i>Checked catalytic converter for loose shields, etc, it is also ok.</i><i></i> <p><i>The rattle seems to be coming from the upper part of the engine andmore</i> <br><i>from the driver side. I have used a stethoscope to locate it, butcan't</i> <br><i>seems to pin point it a specific area.&nbsp; It does however seemto be quite</i> <br><i>strong on the left side (drivers) of engine, possibly in the areaof the</i> <br><i>exhaust crossover pipe. Can't find any loose parts in this areathat</i> <br><i>would rattle.</i><i></i> <p><i>I have a few ideas but need some feed back before taking apart the</i> <br><i>engine to check these:</i><i></i> <p><i>1. Possible worn timing chain tensioner (yeh, the replaced one) andthe</i> <br><i>chain is flopping around.</i><i></i> <p><i>2. Some loose internal baffle in the catalytic converter.</i><i></i> <p><i>3. I don't remember any more, but I beleive the intake manifold gasket</i> <br><i>consists of a sheet metal baffle. Could this have cracked/brokenand is</i> <br><i>vibrating al low rpm.&nbsp; I did have to plug a leak in the intakemanifold</i> <br><i>area with silicone.</i><br><i></i>&nbsp;<i></i> <p>I finally descided to open the timing chain area, and found that theaftermarket chain and tensioner (damper) had more wear and slack after 45,000 kms than the original GM parts after 150,000kms.&nbsp; Since I had saved my old GM original timimg chain and steel gears and in my unexpert opinion they still looked damm good,&nbsp; I descided to re-use them again.&nbsp; Some might say this was not wise, but I was in no mood to spend any more than I had too.&nbsp; I&nbsp; also installed the following new GM parts: <br>1. Damper (tensioner) 25535668 <br>2. Cam buttton 25532434 <br>3. Cam shaft timimg magnet 25530386 <p>I fired it up and guess what, it now purrs like a kitten. Engine doesnot rattle and has the soothest idle that it's ever had. <p>This problem has been reported on a couple of other posts in this NG.&nbsp;Hopefully this info will help some one else.&nbsp; See also this link which talks about the same problem: <br>www.cloyes.com/pdftips/tip9.html <p>Take care <br>Ted M<br>Canada <br>&nbsp; <br>&nbsp; <br>&nbsp; <br>&nbsp; <br><i></i>&nbsp; <br>&nbsp; <br>&nbsp;</html>
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