2003 Chevy Cavalier - motor spins but no compression...

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  #1  
Old 09-29-11, 09:45 AM
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2003 Chevy Cavalier - motor spins but no compression...

My son's car broke down so he had it towed to my driveway (of course). I've never seen this phenomenon before. The motor spins over, or at least the drive pulley with the belt is turning along with the AC compressor, idler, etc. but the engine doesn't seem to be turning over.... I pulled a plug & stuck a compression tester in it & got no reading. I would suspect the other three would read the same. My guess is that he spun the crank between the front bearing & the #1 (or the cylinder closest to the drive pulley end) cylinder, meaning the crank is just sitting still.
The car being 8 years old would probably be a candidate for a crate motor as this one has not been treated the best & has had a few other issues. Any thoughts or input on what's going on here & advise on the best place to get a crate motor would be greatly appreciated. This as a transverse mounted 4 cylinder (I think 2.0L) with a standard trans...

TexasFire
 
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Old 09-29-11, 10:43 AM
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Sounds like you broke a timing belt/chain.
 
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Old 09-29-11, 11:29 AM
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Thats what I was thinking....
A manual trans would have the starter geared to the flywheel. Cranks would be pretty darn hard to actually fracture where the trans end would turn but the rest wouldn't.

Pull the valve cover and see if things are moving.

I sure wouldn't even think of a factory crate motor (if even available) or a even a rebuild when I'm sure there are plenty of these 8 y/o critters in boneyards. They aren't interference motors...so time it up and put a new chain/belt on and it should be the same as before.
 
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Old 09-29-11, 11:40 AM
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Aha.... so a broken timing chain or an issue with that mechanical link could exhibit these same symptoms? The motor spins quite freely with no sound of compressions or anything on the top end. I too thought a crank would be difficult to shear so I'm hoping this timing chain thing is the problem.

Thanks!

TexasFire
 
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Old 09-29-11, 11:45 AM
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And I misread your post...I thought you checked all cylinders. Not sure of all the valve timing...but they all could be slightly open...thus no compression.

Same thing happened to my Dad with an Astra (remember the Pontiac version of a Vega?). He came to help me with a breakdown and when he tried to leave...it would crank all day but not start.
 
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Old 09-30-11, 02:28 PM
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Well...... pulled the valve cover today. Timing chain is definitely broke. Appears that we have at least 6 bent valves. Weighing now whether to re-work this motor or scrap it & go for a rebuild or crate motor. This engine was using oil & had some other issues so thinking not worth much effort. Thanks for all the input. I'll advise how all of this comes out!

TexasFire
 
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Old 09-30-11, 02:36 PM
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Maybe it is an interference motor?

Anyway, given that it was using oil, I think I'd go for a rebuilt.
 
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Old 09-30-11, 02:55 PM
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Per Gates belts...it's not an interference motor. Why you would have bent valves...I duuno.
 
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Old 10-01-11, 06:42 AM
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Vic, Gates only lists timing belts. For chain engines, the mere non-listing doesn't mean it isn't valve-bender, just that it doesn't use a belt. I don't know if that engine is or isn't.
 
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Old 10-01-11, 10:15 AM
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Ahhh duhhh I didn't read the Gates page close enough...
Absolutely correct....Gates lists all the other belts and I was just looking for the interference engine note and didn't even realize they don't list a TIMING belt...just the accessory drive belts.

I bet when it gets broken down..the timing chain isn't broken. I just can't see that happening in a little engine like this. More likely a pin has sheared or a broken cam maybe? Same result of course...it's busted bad

Pull the head is the next step.
 
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Old 10-01-11, 11:10 AM
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grab a motor off salvage yard. it's drop in vs. spend 2 days patching everything back together.
 
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Old 10-01-11, 04:49 PM
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Originally Posted by ukrbyk View Post
grab a motor off salvage yard. it's drop in vs. spend 2 days patching everything back together.
+1 .......................
 
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Old 10-01-11, 04:57 PM
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Said that as my choice in post 3 (unless it was an easy fix).....gotta be tons of them.


btw...I never knew timing chained motors could be interference type.
 
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Old 10-01-11, 06:38 PM
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Originally Posted by 2granddaughters View Post
+1 .......................

I tried crate motors before. then we found we can simply get a used certified one, comes with EVERYTHING, even hoses and wire plugs are still on it. No valve cover removals, no gaskets to mess with. Plug'n'play.
 
  #15  
Old 12-04-11, 07:48 AM
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OK folks, 1st, thanks for all the feedback. For follow up, here's what we did... We looked around for used motors & found one that only had 60,000 miles on it in great shape from a collision car. We found a few at salvage yards but cars that end up there in my opinion have questionable history. Buying an insurance salvage means it came from a car that was being insured & very likely maintained. It passed a multi-point inspection & performance test & compression test results were provided. As was stated, this is much easier than a rebuild, basically just a couple of days to swap motors "plug & play" style. My son says the engine runs great & he couldn't be happier. Engine was $800 & about $800 for the swap. $1600 & he's back in service (car is paid for).

TexasFire
 
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