Running hot

[malibu795]

Condenser hardly catches anything compared to the radiator dirt wise.. Fan clutch wear out.. Clogged radiators obviously make them even less effective

I've dyno ~400rwhp tow ~3x what you do weight wise max egts is 1100° even on the hottest days 95-100 humid south.. I rarely hit 212° ECT.. I also have a decent size engine oil cooler that I keep my oil temps below 240° on those grades, since I'm towing minimum (empty trailer) 8,000lbs up to 28,000lbs 95% of my miles

 

[Chevy1925]

Well I've tried running it at 80 before too. I know its over 1800 there and it's still running hot.

Pushing the truck harder is not going to cool the truck....

 

[malibu795]

Exactly!!!!

 

[danzick]

Right on. Thanks for the tips everyone. I'll do some more monitoring on the way home. I have a big climb home so we'll see. I'll check for the boost leak and clean the rad out. Seems strange to me it runs within like 500 degrees from the 120 tune to stock optimized.

 

[danzick]

Pushing the truck harder is not going to cool the truck....

I was just trying different things. Thought maybe putting the rpms higher might help.

 

[malibu795]

I was just trying different things. Thought maybe putting the rpms higher might help.

I have found that long steep grades are better done in 4th when heavy... Unless you got the cooling capacity to run 5th.. Which you dont

 

[danzick]

8k isn't really considered heavy is it?

 

[malibu795]

8k isn't really considered heavy is it?

Not really.. It's enough to notice there's a trailer back there for someone that's doesn't tow alot..does effect acceleration, braking distance turning and should not becomes complacent about it..

8,000lbs trailer is still within 1500(1/2ton) towing capacity.. If you think about it..most 1500s are rated for 10-12,000lbs.. The Colorado is rated for ~7,000

 

[Chevy1925]

Just out of curiosity, are you running a boost regulator on the stock turbo?

 

[danzick]

Yes. It was pretty much all of the way shut. Datalog shows I'm running about 53 psi steady in 5th on the max effort. 17 from the 75.

 

[danzick]

Not really.. It's enough to notice there's a trailer back there for someone that's doesn't tow alot..does effect acceleration, braking distance turning and should not becomes complacent about it..

8,000lbs trailer is still within 1500(1/2ton) towing capacity.. If you think about it..most 1500s are rated for 10-12,000lbs.. The Colorado is rated for ~7,000

Actually the truck hardly moves unless there is a trailer behind it. I just only have the one 28 ft enclosed cargo trailer I tow.

I should also mention I don't recall ever having high ECT's before the twins. Just always fought egt's.

 

[malibu795]

The 475 adds heat to the oil. In turn increases load on cooling stack..thus easier to raise ECT...
I'd check the stated mechanical items mentioned.. Fac clutch.cooling stack. Boost leak...and install a oil temp.. Oil temps should be 220-230.. When towing

 

[malibu795]

Whole thread about fan clutches
http://www.duramaxdiesels.com/forum/showthread.php?t=65765

 

[danzick]

Great thanks for the tips.

 

[hondarider552]

Every duramax has issues with high engine oil temp while towing, the 75 twins doesn't help it any but certainly isn't the main cause for high oil temps.

 

[THEFERMANATOR]

8k isn't really considered heavy is it?

Depends on what you're towing with. My 95 factory diesel 2500 SUBURBAN was only rated to tow 8000 pounds from the factory(the 454 was rated to tow 10,000 pounds), so for my chassis it is fairly heavy. If I had a newer chassis with a heavoer frame and bigger brakes, then no it wouldn't be that heavy.

 

[danzick]

on the way out I determined 4th is definitely better. pulled a pretty good hill headed home. it was 85 out. I did the first part of the hill in 5th. EGT's started sustaining above 1250 and the ECT was climbing above 200 pretty fast. rpms were in the 1700 range running around 60-65 mph due to the lame speed limits in Idaho. once the ECT hit 220 I hit OD lock out and egts went down to 1050 to 1100 right away. ECT dropped to 217 and maintained that for the rest of the hill. does that help you guys at all?

 

[Awenta]

If I'm real heavy I'll keep in 4th most of the time. 85+ out recently and with 12k up a several mile climb I couldn't break 200 ect. With max 1150 egt

Sent from my SM-N910V using Tapatalk

 

[malibu795]

These engines I have found, to be pretty efficient at 2400-2500rpm pulling grades
68-70mph was 2500rpm in this truck.. .75:1 OD (4L85E/lbz)and 4.63:1 gears..32" tires

 

[Chevy1925]

on the way out I determined 4th is definitely better. pulled a pretty good hill headed home. it was 85 out. I did the first part of the hill in 5th. EGT's started sustaining above 1250 and the ECT was climbing above 200 pretty fast. rpms were in the 1700 range running around 60-65 mph due to the lame speed limits in Idaho. once the ECT hit 220 I hit OD lock out and egts went down to 1050 to 1100 right away. ECT dropped to 217 and maintained that for the rest of the hill. does that help you guys at all?

1700 is just too low. 4th is going to do you better.