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DISCUSSION => Engine + Driveline => Topic started by: roadsterd on January 17, 2008, 12:54:23 AM

Title: Timing chain might not be the problem? (pics)
Post by: roadsterd on January 17, 2008, 12:54:23 AM

To make this quick... I picked up a car, was told that it needed the timing chain replaced.  The car still started up, but sounded like a tractor.  Trying to decide whether to fix the motor or buy a new one.

The cam sprockets and the idler sprocket look brand new, the crank has very light wear.  It almost looks like the timing chain has been recently replaced.  When I bolted on the cam locking tool the cams were slightly out of alignment (maybe a few degrees).

(http://pic19.picturetrail.com/VOL1085/4162020/18811635/298933692.jpg)

(http://pic19.picturetrail.com/VOL1085/4162020/18811635/298933690.jpg)

When I pulled the lower pan, 4 bolts from the upper pan had fallen into the lower and wedged themselves in between the bottom of the pickup and the pan.  There are also some metal shavings in the lower pan but I can't seem to find where they came from.

(http://pic19.picturetrail.com/VOL1085/4162020/18811635/298933686.jpg)

(http://pic19.picturetrail.com/VOL1085/4162020/18811635/298933695.jpg)

The shiny markings on the pickup are where the bolts were wedged in.  You can actually see the threads of the bolts pressed into the metal but the picture didn't come out well.
(http://pic19.picturetrail.com/VOL1085/4162020/18811635/298933694.jpg)

My guess: The fallen bolts were impeding the flow of oil and it wasn't getting enough pressure to the tensioner.  The chain stretched from the slack and caused the cams to go slightly out of alignment.  = M42 that sounds like a tractor.  Sound plausible?

Title: Timing chain might not be the problem? (pics)
Post by: Febi Guibo on January 17, 2008, 08:49:46 AM

This is exactly what happened to my original engine... I kept losing upper pan bolts, and the oiling system couldn't maintain oil pressure, including the timing chain tensioner.

oil pressure = no timing chain slack = your engine not sounding like a cummins-powered sewing machine

anyway, if you can get some rtv up there, replace + tighten the upper pan bolts, put the lower pan back on, top off the oil... I bet yer timing chain will sound okay.

Title: Timing chain might not be the problem? (pics)
Post by: sheepdog on January 17, 2008, 11:08:45 AM

And make sure it is times correctly.

May also want to verify the age of the chain compared to the sprockets, they may have replaced one part and not the other. If the crank sprocket is worn, replace it, and the chain.

Title: Timing chain might not be the problem? (pics)
Post by: roadsterd on January 17, 2008, 12:30:35 PM

I bought the cam lock tool which came with the flywheel lock tool as well.  They are both in place, so no problem there.  One thing I was worried about it getting the camshaft sprockets at 0 degrees.  They are adjustable but have no hash marks or anything to know when it is advanced or otherwise.

I am going to replace the timing chain and the crank sprocket, but nothing else even has wear marks.  I am dreading it but I need to drop the upper pan and replace that gasket too, if you can tell from the picture when the bolts came out the gasket moved and is now covering the bolts holes.