1994 Chevy S-10 timing chain?

Tiny
JMICHAEL8888
  • MEMBER
  • 1994 CHEVROLET S-10
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 165,000 MILES
My engine is a central fuel injected vin W model. I am having problems with low power. I got the truck from my brother and it always has had weak power I am not through diagnosing it yet, but I wanted to rule out the timing chain being the problem. It has no low end or high end power and it idles smooth. Is there any sympotoms or any way to know if the marks are lined up without removing the timing chain cover like maybe removing valve covers and watching valve lift and crankshaft position?
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Monday, December 15th, 2008 AT 10:53 AM

4 Replies

Tiny
JAMES W.
  • MEMBER
First, has the truck always been gutless, or is this something recent? The best "quick check" I've used on timing chains is to grab hold of the bottom pulley and and gently turn it back and forth to check chain slack. You should have a little, 2 or 3 degrees, if you noticeably have a lot of slop, this will retard the cam and hurt performance. Let me know what you find.
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Monday, December 15th, 2008 AT 3:26 PM
Tiny
JMICHAEL8888
  • MEMBER
Ok, just to let you know my truck has a HEI distrubutor with EST (Electronic spark timing) with ESC (Electronic spark control). There is no crankshaft sensor, and the PCM has stored spark advance tables.
I rotated the crank pulley until I felt pressure, then rotated it backwards until the rotor moved. I made a mark near the timing plate on the dampner and rotated it forward until the rotor moved again and made a mark. It is about 8.5 degrees.
I checked the distrubutor gears to the camshaft by twisitng the shaft of the distrubutor. It moved just slightly about a half degree.
I do not understand physics well but when a chain that loose is running, can it get off and hurt performance (low power), or can the pcm tables compensate?
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Thursday, December 18th, 2008 AT 8:38 PM
Tiny
JAMES W.
  • MEMBER
8.5 degrees is quite a bit of wear on a cam chain, but considering 165K on the motor, I'm not supprized. When you figure they dial in the cam on a race car, they go in increments of 1/2 a degree. I would like to be able to tell you that replacing the timing chain will make a marked improvement, but there are a lot of variables. You can look at it this way, it can't make it any worse. Let me know how it comes out.
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Thursday, December 18th, 2008 AT 8:59 PM
Tiny
JMICHAEL8888
  • MEMBER
If I could ask you one more simple question, I checked my timing marks on the dampner. With #1 piston at TDC on compression stroke, and the rotor was pointing directly at "1", the mark on the dampner( or one of them, there are several) was right at 0. I am good to go for now, as far as the timing chain goes? See I wasnt to do a compression test and if the chain is off it could effect the readings, I am a beginner.
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Friday, December 19th, 2008 AT 5:30 AM

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