Howling noise on full throttle

[Lostchain]

Hey all,

New member from the Portland, OR area!

Just picked up my LMTV today!!! I have been wanting one of these for a while. I just made the drive from Puyallup, WA to the Portland, OR area.

The truck makes a strange howling noise under heavy throttle, and quiets up when I lift. Below is a link to a google drive video. I am curious if this is a normal sound on these guys?

IMG_1425.MOV

drive.google.com

Also, anyone in the Portland area interested in meeting up with our trucks somewhere?

 

[simp5782]

Turbo/boost leak. Had one doing it the other day.

 

[Ronmar]

Sounds like an air leak between turbo and manifold… I would start by checking all the hose clamps and look for cracks/splits in the hose couplers. Don’t forget the line from manifold down to air compressor also…

 

[simp5782]

Sounds like an air leak between turbo and manifold… I would start by checking all the hose clamps and look for cracks/splits in the hose couplers. Don’t forget the line from manifold down to air compressor also…

Mine was actually a busted wastegate diaphragm

 

[Lostchain]

Thanks for the suggestions guys, really appreciate it! I will go over it with a fine tooth comb first thing in the morning and report back.

 

[Ronmar]

If you don’t find anything put a boost gauge on it and see at what pressure it starts. Then you can remove the intake and exhaust line at the turbo and cap the turbo ports, then pressurize the system so you can look for it without engine/driving noises…

 

[Lostchain]

You guys were spot on!! It was a boost leak!
First I tested the diaphragm. I set bench top air compressor to 40psi and then blew air into the wastegate hose as indicated in the attached picture.





Then I gently applied pressure and the wastegate moved smooth, and I heard no air escaping.

Then I went through every intake clamp one by one first loosening and re-tightening. What do you know, the one on the drivers side intercooler was loose!! Tightened that joker up and, sure enough, that was the culprit!!

Thanks again for the suggestions!

I did have a strange thing happen when I started the truck up. There is a switch on the dashboard that says warmup, and so for the heck of it I hit it and the engine brake light turned on. Well then when I wanted to drive the truck and see if the howling was gone, I couldn’t hear the turbo at all and the engine wasn’t making any power. I got about a 1/4 mile from the house and decided to turn back because it just didn’t seem right. Well I looked at the PAC brake and it was still physically actuated. So I guess I was driving with the engine brake on…. I tried to manually retract the pac brake but It felt pretty seized shut. After letting the truck cool off I was eventually able to manually open the pac brake, and so I just disconnected it’s solenoid until I could figure out that’s going on with it.

Anyways I fired the truck back up and it drove around like a dream, boosting big time, no howling.

 

[Ronmar]

Yep, the ex brake backpressure is a nice load to warmup the engine at idle. I have an old propane bottle on a pole I put in the exhaust pipe on my A0 to add back pressure for warmup. The pac-brake is supposed to disengage as soon as you step on the throttle though…

 

[coachgeo]

..... I have an old propane bottle on a pole I put in the exhaust pipe on my A0 to add back pressure for warmup. ....

LOL..... that might need just a litttttttttle clarity.

assume you mean an old little camp size bottle to plug the exhaust a bit ; and not you pump some propane into exhaust..

 

[Ronmar]

Yes, green Coleman propane can fits the ex pipe nicely I have seen reference in a few mil vehicle pubs, to a cold weather exhaust restrictor used to warm up the engine. Have never found the actual kit/device or it’s specific publication though…

 

[coachgeo]

Yes, green Coleman propane can fits the ex pipe nicely I have seen reference in a few mil vehicle pubs, to a cold weather exhaust restrictor used to warm up the engine. Have never found the actual kit/device or it’s specific publication though…

how long is the stuff it in stick you made up? assume only foot or less?

 

[Ronmar]

The pole is about 7’(old fiberglass antenna). The pressure generated is considerable. You can barely get the bottom of the canister to set in the ex pipe opening against the flow. The pole rests on the ground against a brick. I have a pic I can put up later…

 

[coachgeo]

The pole is about 7’(old fiberglass antenna). The pressure generated is considerable. You can barely get the bottom of the canister to set in the ex pipe opening against the flow. The pole rests on the ground against a brick. I have a pic I can put up later…

what... no potato in the exhaust .... ejects right when the temp gets about right lol..

 

[Ronmar]

what... no potato in the exhaust .... ejects right when the temp gets about right lol..

Yea, except when the potato lets go it might kill someone…

 

[Ronmar]

Here is what it looks like. I actually have a sketch for something less cumbersome that hangs in a hole with a weighted lever. Some back-pressure really helps with warmup…

 

[Guruman]

That's jank,... hilarious... and awesome all at the same time.