c4 problem engine

[wro87]

We have a 87' with 32k miles. It has always been dealer maintained with all records intact. We now seem to have had something come loose on the lower rightside in the engine it is now making a grinding noise and when the rpm is increased it get louder. Oil pressure (45-60psi)and water temp is fine. At the last oil change (260miles ago) I observed the service tech place it on a different rack which made them have to use a container (antifreeze jug)to put the oil in. I voiceed my concern then about contamination, and they said it would be ok! We are getting ready to pull the engine and does any anyone have anything suggestions as to what we should be looking for? We are saving the oil, it now is still clean but has a very silver scheen to it. I am open to any suggestions and recommendations. Thanks wro87 :confused

 

[tred95]

Don't know about the oil...do you think it might be that the starter gear didn't retract out of the flywheel/flexplate? Just a guess.

 

[taegdh]

The grinding noise in such a generalized area, lower right side.
I hate to think that the fly wheel has loosened and is rubbing on the block, or something like that. Or a bearing bought the farm.

Did you get the noise from standing with the bonnet up, or from the driver's seat? I had a problem noise with a Buick a number of years ago, and I had the worst of ideas going through my mind. It turned out the AC Compressor had run out of oil and was trying to seize itself. Didn't know until I had the local Buick guru take a look at it.

Right side, noise of grinding could transmit itself through the metal of the block and give you the same idea.

LOL,

 

[wro87]

Thanks for the reply. To add on to this we have removed the serpentine belt and we still get the noise. We are guessing spun rod bearing? seems to get worse when you rev it up.

 

[RedRagTop]

The oil has a very silver sheen to it? That don't sound right...
Guessing bad news if it still sounds like that with the belt off.

 

[vettenick]

If the noise is that bad, I think you'll get the answer to your question when you remove the oil pan. Either way, I wouldn't run the motor until you find the problem. Good luck!

Nick

 

[jmccloud]

Grinding noise

A bad rod bearing (even spun) will give a distinct knock, like a ball peen hammer on a big board of lumber. A main isn't much different. Even a cracked 'splice plate' (the thing that connects the torque convertor to the crank in an automatic) will make distinct thunks.
For a grinding noise check the flywheel inspection cover (has it been bent up against the flywheel teeth?) and the oil pan itself to see if it's been pushed up against the oil pump (only takes about 1/6"). I've had both and they make really scary sounds.
And the starter staying engaged is a must check. Pull the starter to see if the gear shaft has been abraided (spinning the starter at engine speed will tear up the gear shaft very quickly).
Look hard before going to the trouble to pull the engine. Don't run it too much, but if you've spun a bearing or cracked a wrist pin, it's time for a full tear down or crate motor anyway.
Hope this helps