Turbo area screeching squeal

[Cummins12V98]

Recently with EB activated a short eeeeeee sound comes on for less than a second or when towing it can be longer. Each down shift it does it. One 50 ambient morning started engine and hit EB and turbo area was a constant eeeeeee. Can’t duplicate.

Chrysler mechanic that worked on my truck for several years doing warranty work we became friends. He has his own shop now. Today he removed air filter box and did a smoke test thru the intake tube, no smoke visible!

He visually inspected EGR cooler & manifold gaskets, no soot! No codes.

He is leaning towards variable portion of turbo bearing or something.

Time to see what my fellow TDR experts say!

Thanks. RR

 

[Ozymandias]

Hard to see the soot, never saw it on mine until I disassembled everything, then on the bare block we're small traces.
From what you say it's 99% the header gasket(s).

 

[Cummins12V98]

Zero noise when accelerating and max boost is 30-31psi. I would think it would make some noise then?

With the cold start that seemed to be odd. It was LOUD.

Looking at boost/braking HP gauge it happens right after crossing over from boost to braking.

 

[Topzide]

Sounds to me like it's the start of the exhaust manifold start to blow by the gaskets. With the gasket being a stamped steel, multi layered, can give that type of sound! Did you try and re-torque any of the exhaust manifold bolts! Like at @Ozymandias states, hard to see the blow by! I has almost no soot until running for awhile with leak. Hope you get it tracked down. Drives you nuts not being able to see or find it!

 

[Cummins12V98]

Wish I would have used a section of hose to locate the source of the sound when it stayed on when I had the EB on the cold (50) start. It was really a "SCREECHING" sound.
Good idea on the re-torquing!

 

[Ozymandias]

Backpressure is up to 65psi, compared to boost pressure that's a lot more.

Mine screamed with the EB on long before I heard it with the throttle down.

In the beginning it was only audible after a long climb an then EB on going into the downgrade, where it faded away within a couple hundred feet.
Heat had a big influence in the early days.

 

[Topzide]

Hopefully, you caught it early, and the re-torque will take! If you due go the way of replacing the exhaust manifold gaskets, get a new set of bolts, exhaust, cooler, valve and crossover tube gaskets. I did it over 2 days in the driveway. Have to gauge my time on projects with the back and neck injuries! Still tackle the things that need to be done, just takes longer! The biggest thing is the planning stage!!!!!!!!!!!!!!!

 

[Ozymandias]

His Max-Care run out, he needs a new 2025 with full Max-Care again.

 

[Cummins12V98]

Maybe 2026, but this one still does the job so…..

 

[Ozymandias]

If you start to drop money in it right now you won't get this back then.

 

[Cummins12V98]

Didn’t have time to tighten manifold bolts. Traveling from TX to SoCal I just used TH to save whatever was wrong from getting worse. I used the EB near Las Cruces NM on 8% grade. Did the same TH on Tehachapi Pass with mostly 5% grades. I am extremely amazed how well TH up to 5% grades can hold 35k with proper gearing.

Ozzy I was 99% sure you were correct it’s exhaust manifold gasket making the noise. Now that I am hearing the noise slightly pulling 6% grades once home for Summer I will move my San Juan Islands boat out of the shop and in goes the LongHorn for a manifold RnR.

 

[Cummins12V98]

I guess I will clean EGR cooler just cuz. Cummins gaskets best or??? Re use bolts or??? Re use manifold??? True manifold surfaces???

Looking for the best repair.

 

[Topzide]

@Cummins12V98, I used the Mahle gaskets, Fel-Pro bolt set. Never fully removed the manifold. Just loosened all the bolts and slipped the gaskets in. I was around 180K when this was done. I hope that you have a set of turbo wrenches to get the joint apart!

If you are going with EGR and Cooler clean, then maybe pull manifold and check for truing up the manifold. If you replace manifold, stay with the stock, less issues.

Just remember to re-torque after 500 miles. The bolts i got had thread lock already on bolts. Not a bad job other than the manifold to turbo joint! Just time consuming with the cleaning of the cooler and EGR system. Small bolt on x-over pipe behind upper hose is a bit of a pain to reinstall.

Glad you found the issue. Had me stumped at first myself!

 

[Cummins12V98]

@Cummins12V98, I used the Mahle gaskets, Fel-Pro bolt set. Never fully removed the manifold. Just loosened all the bolts and slipped the gaskets in. I was around 180K when this was done. I hope that you have a set of turbo wrenches to get the joint apart!

If you are going with EGR and Cooler clean, then maybe pull manifold and check for truing up the manifold. If you replace manifold, stay with the stock, less issues.

Just remember to re-torque after 500 miles. The bolts i got had thread lock already on bolts. Not a bad job other than the manifold to turbo joint! Just time consuming with the cleaning of the cooler and EGR system. Small bolt on x-over pipe behind upper hose is a bit of a pain to reinstall.

Glad you found the issue. Had me stumped at first myself!

Thanks for the info. Turbo wrenches? Are you talking exhaust manifold to turbo?

At a glance I assumed the cooler needed to be removed to get at the manifold bolts. Fender liner removal is needed I assume?

 

[Diesel85]

Thanks for the info. Turbo wrenches? Are you talking exhaust manifold to turbo?

At a glance I assumed the cooler needed to be removed to get at the manifold bolts. Fender liner removal is needed I assume?

I had to lookup a turbo wrench myself. It's appears as if they are "S" wrenches. Tools that I have, but rarely use, but come in handy for tight spots.

 

[Topzide]

@Cummins12V98, Yes, the turbo to exhaust manifold wrenches;

Did everything from the "top". (little dig there) Didn't have to remove the liner or the cooler. @Ozymandias, suggested to loosen all bolts, then remove one cylinder at a time. Do you have FSM? There was a torque sequence, and a "low" torque valve that surprised me!

Here's the thread I started about this issue; https://www.turbodieselregister.com/threads/exhaust-manifold-leak.274807/

 

[Cummins12V98]

"FSM" ? That wrench is worth its weight in GOLD!!!

Good one "TOP"

 

[Topzide]

Factory Service Manual

The one bolt would be darn near impossible to get out and back in!

Glad to pass on the information.

 

[Cummins12V98]

Made it to my Summer home NW WA today. I could have played a tune as the leak got worse by varying the EB.

 

[Topzide]

Your were playing the Cummings "harmonica".

Glad your back were you can address the issue. Good luck with repairs.