Hey Kennedy, Help Please

[Mark-]

OK so the other day while towing my 5th wheel over the Rockies, I finally got real warm. The edge monitor registered 250 deg and the trucks pc flashed engine coolant hot.

2004.5 LLY NE1 emissions code
MBRP catback
Edge w/ attitude set to 1
Banks air cleaner assembly
105k miles
Clean coolant stack
Fan clutch cycles at 234 deg and normally brings the temp back down.

What additional mods would you recommend to lower EGTs & coolant temps?

[Mark Rinker]

I'll jump in with what I have learned of this engine/turbo combo...

It appears that with the advent of the variable vane turbo (LLY, LBZ, etc.) that nearly any Duramax truck can suffer from 'heat soak' when faced with towing heavy loads uphill, high altitude, and especially in warm or hot ambient temps.

The problem starts with the overtaxed turbo (working extra hard to make same boost in thin air) makes its way quickly to the engine oil and coolant. The engine and cooling stack reach their 'tipping point' when the water temps get out of range, and transmission temps soon mirror them, since they exchange heat for good, or for bad.

At this point, the fan and radiator are far too small to keep up, and the coolant can't recover due to the heat it is absorbing from turbo, engine oil and transmission fluid, while still under load...Chernobyl. :(

Luckily the solution is easy, and obvious to most drivers...pull over...ide things back to normal.

The most effective solution is to slow down enough under these conditions to avoid the heat soak in the first place.
Using an early LB7 fan clutch has been discussed, but not proven here (theory is they have earlier engagement point)
Additional oil and transmission cooling capacities and/or efficienciesIt really depends on how much you anticipate seeing this issue. If you haul business equipment into the Rockies daily, this would be a problem. If you plan to travel through the Rockies annually, .... well ....


Did you see high transmission temps as well?

[Mark Rinker]

What additional mods would you recommend to lower EGTs & coolant temps?

It might be one of your 'mods' that is causing the problem, to begin with...

On re-read of your original post, it would be telling to re-run the same mountain, same temps, same speeds with Edge turned 'OFF'. As I've reported before, the Edge tunes seem to be designed with the go-fast crowd in mind, not the tow crowd. You you may have simply seen the result of too-high EGTs and its effect on cylinder head temps, if you only saw a temporary spike in water temp, not water AND transmission temps.

Did you see a marked decrease in oil pressure during this hot water temp episode?

[Mark-]

Well, that's what I did. Turned the Edge back to stock and slowed down. Heat never got above 136 at that point. I guess my question from Kennedy is with boost sticks, finger sticks, egr blockers would any of these help. How about a test pipe instead of the cat? Will that set codes etc. Would any of that help?

The part that gets to me with the exception of constant wiring harness issues, and the occasional high temps, that LLY pulls like a spanked monkey!!

[Kennedy]

This is a tough one. The truthful answer is that there is no fix for all situations. Some claim to have it, but I haven't seen it.

A good exhaust less cat will definitely help as will a good tune on the ECM. The Edge adds all fuel and no boost. Add teh Boost stick and yes you reduce EGT's, but there is only so much a guy can do with a the BS. When I do a custom tune we add boost in some places take away in others and leave alone in others. We cant do that with the BS.

[Kennedy]

FYI there was one mod that did work. Tx Christopher had his rad mod V2 which was a secondary radiator. I don't believe that I ever heard from anyone that actually ran one and was not successful. Those that bought them found it to be the only TRUE solution again from hearsay. Unfortunately Christopher has been MIA and/or unresponsive for some time now from what I hear.

[Mark-]

Thanks for your thoughts Kennedy. I guess I'll just turn the Edge off and slow down on the hills....