Engine bay very hot

376zulu

New member
Nov 9, 2022
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I have just rebuilt this LLY, it had a cracked piston. I have been driving it for months, it seems to run very well. Yesterday, I opened the hood, I thought I smelled fuel. The passenger side of the engine bay, particularly, the turbo compressor intake pipe and the cold side pipe from intercooler, were very hot to the touch. I seems out of the norm.

The truck is not running hot.
My egt sensor is not working, so don't know exhaust temps.
I do not have any shielding on the turbo turbine, or any exhaust parts, except the down-pipe.
The hot pipe from compressor to intercooler is stock.
The intercooler is stock.

Should I put shielding on the turbo?
Should I also, or just, put shielding on the intake/cold side pipe?
Should I upgrade the hot pipe and/or intercooler?

Understand, there is a budget/cost component to the questions. I'd do all of that, if I had the money, but right now, I just want to do the minimum to fix the issue, if there is one.

Any experience or advice would be appreciated.
 

Dozerboy

Well-known member
Jun 23, 2009
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TX of course
Does it have a lift pump? If not the system is under vacuum so it's doubtful there is a fuel leak before the CP3. After the CP3 you have several high pressure lines and fittings that could be leaking a little. Honestly unless you see something leaking somewhere I don't know if I would be too worried about it.

As to the issue of things being hot that doesn't really give us much to go on. Everything should be very hot especially if you've been working the truck hard. What's the weather like where you're at now? If you're up North somewhere and it's pretty cold maybe you do have something going on, but with the information you've provided we can't really give you much to troubleshoot.

I wouldn't worry about the heat shield. Lots of people don't reinstall them when they put different turbos on. I'm unaware of it ever causing any issues.
 

376zulu

New member
Nov 9, 2022
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Yes, it has a lift pump. I'm not worried about the fuel smell. I think I'm just paranoid about any smell or noise, considering it just rebuilt it and that was my first Duramax rebuild.
I was a bit concerned about how hot to the touch, the cold side pipe was. I live in Texas, it is in the high 80s this time of year. I didn't work the truck hard, just a drive, no load/trailer.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
Look up "turbo blanket" for the turbine, since you've removed the OEM heat shields.

Curious if there could be a restriction somewhere in the intercooler or turbo vanes causing the extra heat in the intake system?
 

Ron Nielson

Active member
Oct 11, 2009
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Berryton, KS
If your concern is about the cold side pipe being hot, don't worry. They're always hot, at least in 70+ degree weather. The hot side, of course, is quite hot, then that feeds into the intercooler, then into the cold side pipe. But the cold side piping there will still be hot to the touch
 
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MaxComp88B

Member
Mar 30, 2022
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I was very sprised when I went to touch my hotside pipe once. It is very warm. But you have tho think there isnt a crazy amount of ventilation in those motors. I mean the hotside pipe goes right by the driver-side exhaust manifold. I wouldn't be to concerned.
 

376zulu

New member
Nov 9, 2022
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I have bought larger intake and cold side pipes. I was wondering if there the restriction of the stock hot side pipe and intercooler are causing a restriction that is causing some unnecessary heating on the cold side pipe and Y-bridge. The cold side pipe is routed up and away from the oem pipes route, near the exhaust.
Thanks for the feedback.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
I have bought larger intake and cold side pipes. I was wondering if there the restriction of the stock hot side pipe and intercooler are causing a restriction that is causing some unnecessary heating on the cold side pipe and Y-bridge. The cold side pipe is routed up and away from the oem pipes route, near the exhaust.
Thanks for the feedback.
its more likely to have a boost leak and cause the higher temps than a restriction.

a boost leak will increase temps.