98 K1500 5.7 metal squealing

I’ve got a 98 Chevy K1500 that recently seized my 305 engine. I replaced it with a used 350. The engine runs well. Good oil pressure and good coolant temperatures. Transmission shifts well. My problem is, when it warms up, I start getting a squealing noise. It sounds like metal on metal and rotational. Everything will be fine, but then after about 10 minutes of driving it will start squealing. I can’t tell where it is coming from. If I am pushing hard on the pedal, the squeal goes away. If I let off on the pedal or sit at idle, it squeals. It doesn’t matter what gear it is in, or if it is in neutral or park. It sounds like a rotational metal on metal sound. If I take the belt off, it doesn’t make any difference. It still squeals. I pulled off the transmission bell housing dust cover and it doesn’t look like anything is rubbing and there is no metal shavings in the housing. I even put a washer behind the dust cover bolts to space the dust cover away from the torque converter bolts.

Any ideas? It’s driving me crazy, you can hear me from a mile away.

Wait for it to squeal. Put the trans in "Park", set the park brake, and start crawling around the vehicle until you find the approximate source of the noise. Left--Right--Front--Back--High up--Low-down...etc.

Consider the possibility of a vacuum leak (whistle) rather than "grinding".

The only place a stethoscope gave me any noise was on the bottom of the oil pan. Is it possible the oil pump makes a high squealing sound?

IF this is the oil pump, the first thing I'd do is to pull the distributor cap when the engine is hot enough to be squealing, and verify that there's some up 'n' down play in the distributor shaft.

Doesn't really matter how much--a few thousandths is all you need although there's often .020 to .050.

If there's NO vertical play, you need to pull the distributor and find out why. Common causes are
1. Distributor installed without a gasket between distributor housing and intake manifold
2. Someone has modified the distributor with additional shims to reduce the gap between housing and distributor gear--and they went too far.
3. Improperly machined (aftermarket) oil-pump drive shaft between distributor and oil pump.
4. Improperly assembled oil pump, the drive tang on the driven gear sticking up too high--wasn't pressed-into the gear far enough. This would be really rare, and almost certainly the fault of whoever made the oil pump.

What makes me doubt that the oil pump is the problem, is that I have no idea why the squealing would STOP when you're heavy on the throttle. Doesn't make sense.

I pulled the cap off the Distributer and there is up and down play. Probably around .03 to .05.

Still suspecting vacuum whistle rather than "metal squeal".

You whack the throttle open, vacuum drops, and the whistle/squeal goes away.

Something to keep in mind.

Schurkey said:

Still suspecting vacuum whistle rather than "metal squeal".

You whack the throttle open, vacuum drops, and the whistle/squeal goes away.

Click to expand...

I think you are right about a vacuum issue. If I pull the vacuum hose with the PCV off, the squealing goes away. Maybe I did a mis-routing when I did the engine swap. Where can I find a good hose routing diagram?

Is there a fresh-air vent on the OTHER valve cover? What is it connected to?

The service manual will have a PCV system hose routing, and maybe there's an under-hood decal with that info too...but you shouldn't need it.

Check for a slight leak at #7 or #8 where the intake manifold gasket might be leaking.
If you see weeping radiator fluid near the oil pressure sending unit or drips collecting on your oil filter mount, you may be hearing a manifold leak.

You may not be able to determine the leak using a vacuum gauge, either.

The sound of air screeching by your intake gaskets may be what you are hearing.
It sounds like the bearings on the alternator are bad... except the sound is not coming from your alternator, right?

I had to source the MS98000T steel gaskets with the rubber seals from Summit, in order to get my intake to properly seal on my Vortec 355HO, using the 7116 EDL manifold. Not knowing your configuration, who built or aligned the angle of your heads, whether your manifold is warped, engine decked or heads shaved... there's a lot of variables...

The set comes with extra o-ring intake seals, (which you may or may not require).
This $et ($60.99), is the only way to get these manifold gaskets, as far as I know.

The Mahle/Victor Heinz set, (which show steel gaskets with rubber seals), have been replaced with plastic gasket sets. The Mahle company rep told me they know the photo is wrong and have not updated the pictures in the last 2 years. Do NOT buy the Mahle gaskets based upon the photos on the sale page.

Mahle is good stuff, overall. The plastic gasket sets, ($29 vs $36) are not the same standard as the original Vic Heinz stainless rubber seals.

In fact, after looking at both Mahle plastic versions, the cheaper one and the more expensive set, they look identical.

The rep from Alabama could not tell me the difference either, except for the price.
I had her reach out the engineering team to verify if there was a polymer or gasket compound seal improvement over either version... crickets... no response...

Good Luck!