Squeal from Engine/Trans?

[swathdiver]

Was able to hear it only when the camera was between the engine and transmission. I'm at a loss to know what it might be though. I reckon something is rubbing at a slower pace then engine rpms. If so, what turns slower then the motor while the motor is on and the vehicle is stationary?

 

[OR VietVet]

My best guess is either a vacuum leak near the back of engine, have heard all kinds of leak-pitches in noise levels-over the years or the dreaded squeal from the rear main seal crankshaft rub or the front trans pump to torque converter seal rub noise. Does the noise pitch change when in gear or neutral or park? Does engine load change it, like with a/c on?

 

[winterismyseason]

I watched the video earlier not really sure my best guess is a line under pressure making noise or a pump, maybe pull that transmission thermostat out, do the bypass mod on it and see if that makes any difference it wont hurt anything to try that. easy to do.

I'll wait a little bit before doing the mod, but I'll do some research to see what's involved.

My best guess is either a vacuum leak near the back of engine, have heard all kinds of leak-pitches in noise levels-over the years or the dreaded squeal from the rear main seal crankshaft rub or the front trans pump to torque converter seal rub noise. Does the noise pitch change when in gear or neutral or park? Does engine load change it, like with a/c on?

Learned something while testing this out. First the results. No change with engine load in different gears (P,N,R), or with A/C on/off. Same pitch and volume. What I did find was that increasing RPM off of idle eliminated the squeal. As soon as idle returned, the squeal returned. Hopefully that's helpful.

Next time I get it warm, I'll crawl under and try to do a little better locating of the sound. I'll poke around and see if I can't find a hose that makes the sound change.

Thanks for the help guys!

 

[Big Mama]

That somewhat leans towards Ron’s idea of a vacuum leak possibly a cracked or even a partially clogged line. Chase, to confirm, there are no dash lights or performance issues, correct?

 

[winterismyseason]

That somewhat leans towards Ron’s idea of a vacuum leak possibly a cracked or even a partially clogged line. Chase, to confirm, there are no dash lights or performance issues, correct?

Confirmed, no dash lights or performance issues. Everything mechanically (besides this sound) seems solid.

Regarding performance, and I think it's intrinsic in these, but around 45-55 on flat roads it doesn't have enough torque to pull 6th gear with only 4 cylinders running and will hunt between 4 and 8 cylinders and what I perceive as locking and unlocking the torque converter.

 

[Joseph Garcia]

Unfortunately, I cannot offer anything on this issue beyond what the other folks have suggested.

Am I correct in seeing the starter come into view early in the video, when the noise is the loudest? Is it possible that the spring-loaded starter solenoid gear is not disengaging, once the motor starts?

 

[OR VietVet]

You need a mechanic's stethoscope to help pinpoint the area where noise is from. They are inexpensive and a must for finding noises.

 

[winterismyseason]

Am I correct in seeing the starter come into view early in the video, when the noise is the loudest? Is it possible that the spring-loaded starter solenoid gear is not disengaging, once the motor starts?

I think that's the starter. While poking around with my new stethoscope this evening, I searched that area pretty well, no luck.

You need a mechanic's stethoscope to help pinpoint the area where noise is from. They are inexpensive and a must for finding noises.

Picked one up today. What an amazing little diagnostic tool. Unfortunately I was unable to locate the source. I poked around for quite awhile with no luck.

I feel like I was able to rule out the transmission, although I did notice for the first time that the transmission crossmember is not original to the truck (probably a red herring for this issue). It doesn't have the same waxy undercoat as everywhere else. (undercoat is covered in sand and silt from a couple remote camping trips in southern Utah, not rusty).


I also noticed the trans support has some musical notes... It's off topic, but still interesting.


The more time I spend under the truck while it's squealing, the further forward I think it may be. I'll have to drop the plastic skid pan and do some more stethoscope-ing this weekend. I'll update with results.

 

[mikeyss]

It throws me off that the noise is only under the trans, but not from up top of the engine. To me, it sounds belt/tensioner related until you stood by that area and the noise is gone. I am guessing a vacuum leak, especially since the vacuum pump is on the driver's side where I hear it the most from your video.

 

[Big Mama]

Once the bottom cover is off you may find that the sound is kind of bouncing around all that metal and is coming from a tensioner or AC