squeeling oil pump?

[pilothillcrawler]

I got an 88 TPI corvette 350 in a YJ that has a bad squeal coming from the back of the motor, I have had the local 4x4 shop tear the trans and everything apart this last week, the noise only starts after the motor has warmed up. If I use a stethoscope to isolate the sound it sounds like it is coming from the very back of the block or around the distributor. My question is could it be the oil pump, has anybody ever delt with anything like this? I am at my wits ends trying to figure this noise out. Also, when the noise starts it gets the worst when you rev the motor and let the RPM's fall back down it squeals on the way down bad. I am asking this assuming the oil pump is towards the rear of the motor, I don't have a whole lot of knowledge, but trying to learn.

[redbeast]

I'm no expert at this stuff, but judging from the location you suspect the sound is coming from I would think a bad distributor, distributor gear at the shaft end, or an oil pump, although I've never heard of an oil pump squealing, personally. Have you listened at the bottom of the engine near the oil pump - to see if it's coming from the bottom or the top of the engine ?
Watch out you don't get snagged by the turning gear while you're under there.
I'd also take the oil pan off and see if the oil pump pickup tube separated or there is something in the screen impeeding the oil flow.
Also do you have the same problem with the truck in gear as out of gear ?
Transfer case in neutral too ?
Vacuum hose leak ?

[pilothillcrawler]

I took the Distributor out and took it to napa and compared it to a new one. the only difference was mine had about a 1/4" of play up and down and the new one had a little less, there was no slope in any other direction and the rest of it looked good. It is tuff to tell if the noise is coming from the top or the bottom of the engine. I will have to check the tube, etc. The problem is there no matter what the trans is in. I never tried it with the t-case in neutral or not because the noise was not coming from back there. the trans is an sm-465, no vacuum hoses.

[KWTMECH]

My thought is if the oil pump was/is squeeling then the engine would be toast at this point. I would lean towards the distributor bushings

[pilothillcrawler]

I figured there would be horizontal slope in the distributor if the bushings were bad. that was the only reason I did not replace it when I had it out last time. would a little vertical slope be a sign of the distributor bushings gone bad?

[spurren2]

I have something real similiar on a 98 4.3 and turbo 350. I thought it was comming from the front of the tranny though. The squeal only starts when its warm and goes up[ and down with the rpm. Im trying to get this figured out. Post up if you get yours figured out

[tpi_boy]

Is this a new motor? I've had a dry rear crank seal squeel before. Just an idea.

[odin544]

oil pump is at the back of the engine bolted to the rear main cap. i would suggest trying a different distributor.

[muzy]

Check all vacuum lines and connections ? Blocked exhaust or restricted.

[pilothillcrawler]

Originally Posted by spurren2

I have something real similiar on a 98 4.3 and turbo 350. I thought it was comming from the front of the tranny though. The squeal only starts when its warm and goes up[ and down with the rpm. Im trying to get this figured out. Post up if you get yours figured out

From the little bit you said it sounds like we might have the exact same problem. did you ever change your distributor? I thought it was my tranny also. had the damn thing rebuilt, new clutch, pressure plate, throw out bearing and everything.

[pilothillcrawler]

Originally Posted by tpi_boy

Is this a new motor? I've had a dry rear crank seal squeel before. Just an idea.

The motor is an 88 so it is old. I have thought about the rear seal or main bearing. I was just hoping it wasn't coming from there.

[spurren2]

I havent got to the distributer yet. I took the tranny out today and am going to switch TC and see if that solves anything. The squeal kind of lobs at lower rpms and gets more constant a higher rpms ??????

[spurren2]

are you going to try a new distributer?

[Duallie]

I once had a squeal from the rear of my Buick, but it was only when warm and accellerating. Turned out to be the dust pan hitting the torque converter. Take the dustpan off and see if it still squeals.

[redbeast]

I've had a HEI distributor shaft snap on me before. I've got one I just pulled outta my truck sitting around if you want, I'll sell it cheap. Just replaced mine with an MSD pro billet. It's got a new cap & rotor from Summit. Only a few hours on those. The dist is a factory rebuilt I've had for a few yeras. I've also got a spare electronic module for it I'll throw in. Let me know if your'e interested.
If you want to set the distrubutor theory to rest try getting an engine stethescope, set at the base of the distributor - at the intake manifold and it should be apparent if the noise is coming from the distributor. Be careful you don't get snagged by the turning machinery if you do this test.

The torque converter dust cover sounds like it could do that sqwealing thing too. especially if you hit something off-road and it's rubbing lightly on the flywheel.

[pilothillcrawler]

Originally Posted by spurren2

are you going to try a new distributer?

yeah I might try it this next week.

[49willys]

Sounds like a thrust bearing failure. How hard is it to pull the pan? If'n it was me I'd want to take a look at the rear main bearing before I ran it any more.... just my $.02

[Buckshot33]

squeeling indicates bare metal on metal with no lubrication... and it is a wet sump OIL pump... I'd look to the dist..

[TatorZuk]

I got an 88 TPI corvette 350

Very common to have a dry distributor shaft bushing making noise in these years...try taking the shaft out and lubing it before buying a new dist.

Very easy...and costs nothing.

[pilothillcrawler]

Originally Posted by TatorZuk

Very common to have a dry distributor shaft bushing making noise in these years...try taking the shaft out and lubing it before buying a new dist.

Very easy...and costs nothing.

From everything said I think I will try the dist, where would I lube it? just down towards the bottom, and with what kind of lube?

[GMCTruxrule]

Originally Posted by Buckshot33

squeeling indicates bare metal on metal with no lubrication... and it is a wet sump OIL pump... I'd look to the dist..

Yes, I think that it is safe to eliminate anything in the bottom end of the engine as being the culprit for this squeeling noise.
Thrust bearings, rod bearings, main bearings, oil pumps, if the engine has oil pressure, NONE of those components should squeal.
Don't forget stupid little things like alternator bearings, power steering pumps, flex plates, torque converters, anything with moving parts that ISN'T lubricated by oil could be suspect.
Vacuum hoses not connected can squeal.

[pilothillcrawler]

I have seen a few people mention vacuum hoses. Any ideas on if the sound from the vacuum hoses would change with RPM's?

[GMCTruxrule]

Well yes, it would change, more noise as engine rpm/vacuum increases.

[spurren2]

if it was a vacuum hose, wouldnt it squeal from the start up? Try spraying some ether around the vacuum lines and see if the RPMs go up

[TatorZuk]

Originally Posted by pilothillcrawler

From everything said I think I will try the dist, where would I lube it? just down towards the bottom, and with what kind of lube?

You have to pull the dist...

then you drive out the roll pin holding the gear on...

then remove the dist shaft from the dist housing...

lube the shaft where it turns inside the housing...