Running hot

danzick

danzick

playing with fire
Feb 20, 2014
576
16
18
Livingston, MT
Headed for a weekend trip. Pulling a steady incline for about 10 miles. No matter what tune I run it wants to run steady 1250+ to maintain 70 in 5th. Pulling about 8,000 pounds. As it got steeper for the last mile It ran at 1300 and up and 230 plus. Fan was screaming away and it wouldn't cool off. Hit the top of the hill at 236 and it finally started cooling off after we went down hill. What would be causing this? Turbos are running very close to a 3:1 ratio on boost. Was running about 30 psi steady on the last steep mile.
 
Burn Down

Burn Down

Hotrodder
Sep 14, 2008
7,093
28
48
Boise Idaho
Boost leak can cause egt's to climb like that. LB7/LLY intercoolers don't have the corners finish welded and most all leak there, some worse than others. Build a plug and pressure up inlet of the big turbo to check for air leaks.

What did your EGT's do when you down shifted to 4th?
 
danzick

danzick

playing with fire
Feb 20, 2014
576
16
18
Livingston, MT
Just recently checked for leaks. Took like a minute to drop from 16 psi to 3. Egts will drop down when kicked to 4th, but I'd rather maintain 5th. Truck has all the power for it.
 
Awenta

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
In 4th you would have higher fan speed also. Maybe your fan clutch is on its way out.

That's too hot for 75 degrees outside.

Sent from my SM-N910V using Tapatalk
 
baggedLB7

baggedLB7

Goer
May 1, 2011
688
4
18
Utah
My egts run 1230-1260 pulling decent grades with the boat holding around 1800rpm.
What was your oil pressure at the top and do you have an oil cooler or oil temp gauge?
 
loganater

loganater

New member
Nov 20, 2014
27
0
1
whatever town im working in
my lb7 does that at 5% grade with 9500 lbs im not going to say thats normal. i have yet to see what normal is. nobody seems to have a definate answer on egts. i dont have any tunes. now i think i might have a problem too.i drop to forth for sure to go easy on it
 
THEFERMANATOR

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
3,890
43
48
43
ZEPHYRHILLS, FL
I've yet to break 225 with mine going up a 6% incline with about 9000 pounds in tow. My BURB has a MUCH smaller grille opening than newer trucks have, but even with that the fan kicks in aroudn 220 and brings it back down. I know I could hold 60 easily with the fan clutch barely kicking in on a 5-6% grade. Clean the cooling stack like posted above, and replace your fan clutch.
 
Chevy1925

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,147
4,904
113
Phoenix Az
danzick said:
Hm.... Cannot remember. I'm pretty sure above 1500 and under 2000
Click to expand...


This is kinda important. At or over 1800rpm, those are high egts. Below that and your on par.

You more than likely need a cooling stack cleaning though and make sure the boost leak you have isn't worse
 
danzick

danzick

playing with fire
Feb 20, 2014
576
16
18
Livingston, MT
I should also add this is trying to maintain 70 to 75 mph. I'm sure it would run cooler in 4th doing 65 but I'd rather use the 400+ HP I have.
 
Chevy1925

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,147
4,904
113
Phoenix Az
I've seen them packed at 30k. Doesn't hurt to pull the intercooler and clean.

Your 400+hp isn't at 1800rpm.
 
You must log in or register to reply here.
Top Bottom