1994 Chevy Blazer Possible timing chain. Or worse?

BADBOY4UNIX

MEMBER
1994 CHEVROLET BLAZER
6 CYL
4WD
AUTOMATIC
138,000 MILES

My sons 1994 S10 Blazer, 4.3LTR Vortec V-6. Engine started and ran fine for the first six months he drove it. Then one day he started it cold and while driving it locally (< 30mph) for less than a mile it started running very rough and losing power, he states he had to press the accelerator down almost all the way to get any power at all, within another half mile the roughness and power loss got so bad it finally stalled. After that the engine *cannot* be restarted as it will only crank about one revolution before getting "stuck" while trying to turn over. After shutting the key off and letting the engine sit a while the same scenario repeats itself. My mechanic friend took a look and said the engine is "shot" with no specific diagnosis. A friend suggested it is a slipped timing chain and could probably be fixed without replacing the entire engine. Thoughts?

6 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Wow, this is a good one. I'm going to give my opinion. If the timing chain slipped, the motor wouldn't lock. It wouldn't run, but the starter should still be able to turn. If something internal (rod, main. Crank.) Broke, it would have turned a little, locked, and never changed. Steel doesn't move once it is locked. I want you to check something for me. Remove the spark plugs and see if one of the cylenders is full of coolant causing hydrostatic lock. Also, check the engine oil to see if it looks contaminated with coolant. When the plugs are out, see if the engine cranks.

Let me know what you find.

Joe

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Tuesday, March 9th, 2010 AT 10:28 PM

BADBOY4UNIX

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3 POSTS

Removing the plugs showed 5 dry but slightly black plugs, the middle rt plug, #3? (Facing the engine) was black and WET! It was like a slimy wetness, could not tell if it was green or not.

The engine cranked over just fine many times after I pulled the plugs. I forgot to check the oil for anti-freeze. Sorry. But I have a feeling there is antifreeze in there.

So my amateur mechanic friends tell me that I should. Buy a "cylinder leakdown" tester, a "cooling system pressure tester" and get ready to change a "head gasket"

Any advice and or guidance would be deeply appreciated.

Thanks.

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Friday, March 19th, 2010 AT 10:02 PM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Save your money and get a compression gauge. Most parts stores will lend or rent one to you. Check engine compression to see if there is a low cylender. That would most likely indicate a head gasket. The interesting thing is that it cranks without the plugs. I realize it will crank much faster, but do you hear any metalic noises when you crank it? Also, now that you have removed the plugs and got it to turn over, you may want to replace them to see if it will start. If there is a bad rod or crank bearing, you will hear it when it runs.

Let me know what you decide. As far as the tools, check out a nationally recognized parts store. Most will lend or rent the tool to you.

Joe

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Monday, March 22nd, 2010 AT 1:23 PM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

You know, I reread the original question. Is there any chance the battery was weak? Also, now that it is free to crank, check the ignition timing to make sure it wasn't firing too early and causing this problem.

Joe

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Monday, March 22nd, 2010 AT 1:26 PM

BADBOY4UNIX