High EGTs w/ KB Diesel 64mm

[715Hunter]

Hi guys,

Been having this issue on a 2004 LB7 for awhile, and would love to get to the bottom of it. This truck is not tuned and is 95% stock: just running a Banks intake, 3" downpipe, no cat, Mahle cast pistons thermal coated, and the non-stock turbo. It's a 63.5 mm full front kit coupled with the 10 blade turbine. I wanted the 11 blade stock turbine, but it was out of stock when I needed this.
Symptoms are as follows: at WOT pyro climbs through 1,400° immediately and will break 1,500° if I stay in it. After about 20-30 seconds the engine temp starts coming up. This is really only a problem above 60° ambient. In the winter it stays cool. (This is weird too,the cooling stack was robbed from a built LLY that ran way harder than this and never wiggled the needle)
I can let off and keep it under control, but with out enough power to really pull hills while towing. I'm tired of pulling hills at 35 MPH, and don't want to hurt a head gasket.
Any insight on this? My instinct is bad turbo or bad rebuild by me, but I don't want to drop 2K on a Cheetah if the problem is elsewhere.
Thanks in advance!
EDIT: Between 2,500 & 2,700 RPMs it behaves perfectly. Won't break 1,400°, doesn't drive up engine temp either.

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[darkness]

What kind of boost are you seeing? Have you checked for boost/drive pressure leaks?

 

[Ridin'GMC]

You definitely have a boost leak. Pressure test your system and listen for leaks. Or spray soapy water on all the tubings, even at the intercooler.

 

[Dozerboy]

Maybe your Pyro is bad too. What are you using? I had 1 go bad every couple years. I think it was a Ktype. I bought new speedhut gauges about 8 years ago and never had a problem since.

 

[Bdsankey]

Step 1 would be checking for boost/drive leaks. Feed 40-50psi of air into the front of the turbocharger and spray all charge air piping connections and the intercooler with soapy water. Inspect all exhaust connections (head > manifold, manifold > up-pipe, up-pipe > turbo) for any signs of a leak like soot.

Step 2 would be to verify the pyro is good. What brand pyro is it?

What boost does the truck make on a mechanical gauge for boost?

 

[1FastBrick]

I am not familiar with diesel tuning, but i have to ask other that are.

A bone stock tune is safe enough to compensate for a larger turbo?

 

[2004LB7]

I am not familiar with diesel tuning, but i have to ask other that are.

A bone stock tune is safe enough to compensate for a larger turbo?

It would overboost and underboost, throw codes and likely go into limp mode reducing fueling. Depending on how much larger the turbo is over stock

 

[Bdsankey]

I am not familiar with diesel tuning, but i have to ask other that are.

A bone stock tune is safe enough to compensate for a larger turbo?

It would overboost and underboost, throw codes and likely go into limp mode reducing fueling. Depending on how much larger the turbo is over stock

^ Agreed.

Based on his post of it being a 64mm, it would benefit from a tune but doesn't "need" it to run reasonably well. I think there are other issues at play.

 

[715Hunter]

Maybe your Pyro is bad too. What are you using? I had 1 go bad every couple years. I think it was a Ktype. I bought new speedhut gauges about 8 years ago and never had a problem since.

It's an Autometer GM factory match. I'm 99% sure it's fine, as it reads normal temps in the 2,500-2,700 RPM range.

I've been very busy and out of town, and same thing next week. I'll try checking for boost leaks next.

As far as boost: There's no aftermarket gauge installed, so I'm just looking at OBDII data. Boost is reading a max of 32 PSI, but I believe that is absolute and atmospheric should be subtracted from that. If so, that means it's making around 16 PSI.

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[Dozerboy]

It's an Autometer GM factory match. I'm 99% sure it's fine, as it reads normal temps in the 2,500-2,700 RPM range.

I've been very busy and out of town, and same thing next week. I'll try checking for boost leaks next.

As far as boost: There's no aftermarket gauge installed, so I'm just looking at OBDII data. Boost is reading a max of 32 PSI, but I believe that is absolute and atmospheric should be subtracted from that. If so, that means it's making around 16 PSI.

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Doesn't sound you have much of a boost leak if you do, but only one way to tell. Going to have to check for leaks.

 

[Bdsankey]

It's an Autometer GM factory match. I'm 99% sure it's fine, as it reads normal temps in the 2,500-2,700 RPM range.

I've been very busy and out of town, and same thing next week. I'll try checking for boost leaks next.

As far as boost: There's no aftermarket gauge installed, so I'm just looking at OBDII data. Boost is reading a max of 32 PSI, but I believe that is absolute and atmospheric should be subtracted from that. If so, that means it's making around 16 PSI.

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This is very low. OEM trucks make more than this. I suspect you have a boost or drive leak somewhere.

 

[DAVe3283]

Which PID are you using to read boost? The LB7 will cap the reported boost on the SAE PID if I recall correctly.

There is a PID that can read higher, but the stock boost sensor only reads up to like 30 PSIg so with an aftermarket turbo you really want to swap that to a 3-bar or higher then rescale it in the tune.

If you can confirm you are only seeing 16 PSIg of boost that does indicate a problem. But start with a boost leak check.

 

[Dozerboy]

This is very low. OEM trucks make more than this. I suspect you have a boost or drive leak somewhere.

He said he was stock tuning from my understanding. 18-20 stock is normal IIRC

 

[Bdsankey]

He said he was stock tuning from my understanding. 18-20 stock is normal IIRC

My truck on factory programming made ~22psi and my fathers makes 20-22psi, this is what I was basing my statements on.


At my elevation, they tend to make 20 ±2psi or so.