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Old Sep 3, 2009 | 07:15 PM
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Default Questionable Diagnosis

My friend has a C5, of which I know nothing because I have a C4, however, my buddy called me with this story.

He took his car in to a mechanic because he thought that he had a squeaky idler pulley. Mechanic said yes and ordered new idler and tensioner.

Then the mechanic called to say the harmonic balancer was bad. The harmonic balancer had been replaced about 18 months ago, but my buddy OKed that repair also.

On the third day the mechanic says that there are pieces of metal coming out of the engine and that is what damaged the harmonic balancer. My buddy went to see what was going on and the mechanic showed him what looks like a "C" clip that came out of the engine, and he (the mechanic) says that he can see inside the engine and it might be the oil pump.

At this point I started to wonder a little bit about all of this. On my C4 LT-1 the oil pump is in the rear of the engine, not the front. And how can you see inside the engine, even with the timing chain cover off?

This all may be correct, because I don't know "anything" about a C5. But does this sound correct?

Thanks for your input.
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Old Sep 3, 2009 | 07:51 PM
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Well, the C5's oil pump is on the front of the engine, under the timing chain cover, right behind the harmonic balancer. The oil pump is attached with bolts not a C clip though, so I don't know where the clip came from unless it's an internal part of the pump. Seeing inside the engine from that vantage point wouldn't give you much of a view.
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Old Sep 3, 2009 | 08:01 PM
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Originally Posted by LBYRNES
My friend has a C5, of which I know nothing because I have a C4, however, my buddy called me with this story.

He took his car in to a mechanic because he thought that he had a squeaky idler pulley. Mechanic said yes and ordered new idler and tensioner.

Then the mechanic called to say the harmonic balancer was bad. The harmonic balancer had been replaced about 18 months ago, but my buddy OKed that repair also.

On the third day the mechanic says that there are pieces of metal coming out of the engine and that is what damaged the harmonic balancer. My buddy went to see what was going on and the mechanic showed him what looks like a "C" clip that came out of the engine, and he (the mechanic) says that he can see inside the engine and it might be the oil pump.

At this point I started to wonder a little bit about all of this. On my C4 LT-1 the oil pump is in the rear of the engine, not the front. And how can you see inside the engine, even with the timing chain cover off?

This all may be correct, because I don't know "anything" about a C5. But does this sound correct?

Thanks for your input.
Sight unseen....who knows..

My guess is, a misdiagnosis with the tensioner to begin with, might have been the balancer all along. I'm not sure how something could have come out of the engine and damaged the balancer.. With the timing cover off, the chain and oil pump are exposed. The the cover on, you can see anything....unless the crankshaft oil seal was completely gone.
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Old Sep 3, 2009 | 09:33 PM
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Timing cover on


Cover off

Last edited by Patches; Sep 3, 2009 at 09:35 PM.
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Old Sep 3, 2009 | 09:34 PM
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Here is a picture with the cover off minus the oil pump"



LS1 With oil pump:

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Old Sep 3, 2009 | 09:57 PM
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Originally Posted by LBYRNES
"and he (the mechanic) says that he can see inside the engine and it might be the oil pump."
I'm wondering how the mechanic could possibly see the oil pump on a C-5 unless there was a major hole in the timing cover and it was spraying oil all over the place?
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Old Sep 4, 2009 | 09:16 AM
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Sounds to me (with limited info) that the balancer began to wobble (common problem) but the owner kept driving it. The vibration caused by the wobble in the end of the crankshaft leads bearing friction (and thus, premature wear). When the bearings overheated, they started coming apart and contaminated the oil pan, perhaps sucked into the oil pump and causing it to also act up.

BTW, I don't think there is a c-clip anywhere inside the crank case. A picture of that piece would be worth 1000 words.
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