2005 5.3l crank squeal

[Johnb21]

I am getting a bit nervous as I have tried to diagnose a high pitched squeal coming from my truck.
The noise sounds like it is coming from down low, from the crank.

Here's the condition for the loud squeal. Approximately 30mins into my commute, which includes stop and go, I hear a squeal developing from the engine bay. It gets progressively louder over the course of about 1min and the volume of the squeal peaks. The squeal only comes about when the engine is at 1000rpms or less (so like stopping in a drive through for a coffee idling is really embarrassing, as much louder than a typical belt squeal). When I start the truck in the morning, and again for like the 1st 15 miles or so, NO noise.
So here is what I have done so far...
replaced alternator, serpentine belt, and pulley next to alt less than a year ago. Replaced serpentine tensioner (last night), and cut the A/C belt last night.
On my way into work this morning..same thing about 30mins into the commute the noise is back, 1000rpms or below. When I parked the truck I got underneath and it really sounds like it is coming from the crank or bottom of the engine. It sounds like metal on metal.

Oh, oil pressure is north of 20lbs, probably closer to 30lbs. This is according to my gauge and OBD reader (torque)
Please help! Thanks for the ideas.

 

[Johnb21]

Keep forgetting things...apologies.
I replaced the water pump about 5 months ago.
Used a stethoscope last night on the alternator, ps pump and water pump and didn't get any unusual noise.

 

[dubyagee01]

AC on or off?


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[Johnb21]

a/c belt removed and a/c off

 

[clandr1]

a/c belt removed and a/c off

Could be a pulley with bad bearings. My wife's Jeep had the exact same symptoms and it turned out the stationary pulley (that is only there to serve as a pivot point for the serpentine belt) was making the noise because the bearings finally failed after 10 years. It was a quick, easy, and cheap fix.

 

[Johnb21]

I appreciate the responses, but the pulleys are all new or fairly new. All spin tight and smooth...The noise appears to be coming from very low..the crank. metal on metal sound.

 

[clandr1]

There have been a couple of times over the years where I was in your situation - something was wrong but I just couldn't nail down the cause. In those instances, I take it to the dealer and ask them to diagnose it. Then, once they nail it down, I pay them a diagnostic fee and fix it myself (if I'm up to the task). Might be a good way to proceed if you don't get any guidance here.

 

[Johnb21]

Ya, I understand....I am going to try and get a friend who is a toyota mechanic and used to build chevy v8's to take a peak...just nervous even driving it...feels like I could be wrecking the bottom end.
Hope someone on this forum has some experience with something similar...

 

[drakon543]

Honestly if it is the bottom end and its making any noise the damage is aleady done. Anything at that point done to make an interior noise go away is just a bandaid. If you have a stethoscope you should be able to place it directly on the oil pan the same way. If its a loud squel i wouldn't have the buds directly in your ears right away tho.

 

[Johnb21]

ya, I know you are right, but just can't accept it..
I will stethoscope the pan tonight...earbuds at a distance.

 

[clandr1]

What year and how many miles on your truck John?

 

[Johnb21]

2005 161k..
With both belts removed noise still there..
Oil pump? Torque converter? I am baffled...

 

[Johnb21]

Truck runs fine except for chasing a p0171 74 codes that should having nothing to do with it....I have tried all sorts of vacuum leak tests.....and they aren't related timing wise.

Good oil pressure. ..clean oil, clean tyranny fluid..

 

[Johnb21]

Cracked flex plate?

 

[Johnb21]

Well, did a bit more diagnosis and the sound is definitely coming from the bell housing. It doesn't sound like a typical cracked flex plate, but in the same area. Something must have to do with heat, because it takes about 30min or so driving to get the noise to activate. Once the truck cools, its gone until another 30min of driving.

 

[Johnb21]

So I narrowed the noise down and it seems to be coming from the belling housing. All I can think of is a cracked flex plate, but the symptoms seem a bit different.
I think...usually a cracked plate will make noise all the time. Mine requires the truck to be driven for 30min or so. I guess if I left it in the driveway running for 30min, I might expect the same loud squeal. Just kinda strange and not convinced it is the flex plate.

Any other thoughts out there? Either way, I think this is not going to be a small repair bill.

 

[drakon543]

Any repairs in that area will be costly. I know the 5.7 has a lower flex plate/tc gaurd plate that can be removed pretty easily for inspection.

 

[Johnb21]

It does. Have a round like plate about 2 inches in diameter for inspection. .not sure how much one could see...but can't try..
Thanks

 

[drakon543]

Ahh the 5.7 has a separate piece on the bottom of the bellhousing. With that removed you could see the whole setup down there. Well just throwing it out there. Ive never heard one do it but i suppose on the off chance that you had a 1 in a million. The basic design of a tc i could see the possibility that it could squeal once its warmed up. Its a hard problem to diagose just using your information without actually being there and digging into it.

 

[Johnb21]

Ahh the 5.7 has a separate piece on the bottom of the bellhousing. With that removed you could see the whole setup down there. Well just throwing it out there. Ive never heard one do it but i suppose on the off chance that you had a 1 in a million. The basic design of a tc i could see the possibility that it could squeal once its warmed up. Its a hard problem to diagose just using your information without actually being there and digging into it.

Thank you James. I will pull the small plate and inspect this weekend. I appreciate your continued interest to help out!! John