Bad bearing sound during deceleration, with Exhaust Brake on

Hello and Good day. Went thru most old posts/threads about what is called Exhaust leaks, exhaust brake issues. While I have been around machinery and vehicles for most of my life, working as a Wrench. I have not heard a sound like this coming from the Exhaust system. Whistles yes, when a exhaust componet is leaking, whistles on Boost side, Yes. But not this sound.
I would have to say it is a high pitch sound like a ball beaing failing. Like a idler bearing failing. This only happens with the Exhaust brake engaged and deceleration after going along for a few seconds. I can disengage the exhaust, just after Accelerate to speed, and decelerate with no noise. Then accelerate with EB on and have the noise return.
Typical boost is still about 28-30(does not hit 30 easily, never has), EB rating close to 80lbs per Ram stock
gauge.
Replaced the serpentine belt a couple of months ago, along with the idler bearings, and the tensioner pulley.
At about 150k miles

I am perplexed. Any ideas??

This is a wonderful forum. Love reading and seeing the respectiful interaction. Something that does not happen much in the world today. Maybe this will help some one beside me.

Thanks

 

possibly one of the replacement bearings defective? where did you source the parts?

 

It is most definitely an exhaust leak. The culprit is usually the gasket between the EGR cooler and manifold, but could also be one of the manifold gaskets where it mounts to the head. It takes quite a bit of backpressure for the leak to happen, but when it does, it produces one of the most awful squealing sounds you've ever heard. Crawl under the truck with a flashlight and check for black spots or streaks near the gaskets.

 

Idlers are Gates, made in Canada. not Amazon
Can not think how the bearings will only make sound when the EB is on and Decelerating. But anything is possiable. Time for my Chasis
Ears to come out to play.

Well, Mikey I will look. Crazy it could sound like a bearing going bad.

 

I didn't mention it, but check the gasket between turbo and manifold as well. With any luck, you might find a loose fastener.

Just looked on YouTube real quick and found a video that shows a good example. Right at 9:30 in the video, you can hear the squeal really good, and about the 11:30 mark, you'll be able to see the manifold off of the truck, so you can get an idea of how many potential leak points there can be.

 

If you find the leak to be at the manifold, new fasteners would be recommended. I'm about to replace all gaskets on exhaust manifold and cooler with new fasteners. Having the squeal with EB on. No boost issues, just the whistle of a leak with EB! Not that bad of a job, just want to start with a cold engine and have a 2 day window. Good luck.

 

When I replaced my manifold gaskets, I ended up installing studs. New hardware is definitely better to work with. Also, chasing all the threads with a tap is a good idea.

 

I ended up purchasing a thread chaser kit years ago for just such things! It won't cut new threads which a standard tap will do if not careful. Also handy for identifying the thread on a nut or bolt. Also had thread files for those difficult bolt threads. Has both SAE and metric sizes. Very valuable addition to the toolbox!

 

I have tried looking at the manifold at the head with a mirror, and while I can not see any black carbon traces. I do not know where it might be. I have tighten the clamps on the EGR system and the exhaust dump to exhaust. While I do not think this will cure the issue. I will need to order the Exhaust manifold gaskets and Turbo mount gasket. Way to busy with my work to be taking on this work. But needs to be done.
New studs are a good choice. Will order up a set as well.
Yes, no loss of EB or Boost at this time, just noise.
Thanks for all the suggestions.

 

Just read Topsize's Thread and all the suggestions there. No need to repeat, will follow some of the Suggestions there. I totally forgot about
the Bore scope approach. I have one, and will use it next to take a look.

 

Well I dodged a bit of work at this time. The tightening of the V=Band clamps on the EGR pipe Took care of my noise. It is currently as quite as before.
Thanks for all the great suggestions.

 

Sure beats replacing manifold gaskets! Glad you got it taken care of.

 

I agree,