6.5 towing and heat

[a5150nut]

Where do the 6.5 heating problems come from?

I know Kennedy has a better fan setup. But do the problems stem from pump capacity, radiator size, or block design?

Would a larger radiator or auxilary radiator be of any advantage?:confused:

[JohnC]

I had a '93 with a standard trans, Never had the slightest indication the engine even considered running warm. My '95 was an automatic and it would get hot on a long pull, pretty regularly. The difference, IMHO, is the radiator mounted trans cooler. The cooling system just isn't big enough to cool both the engine and the trans.

[greatwhite]

Gawd, where do I start? It's a combination of things:

1. IDI design. This design tends to hold more heat in the heads than.....say....a DI diesel. It's inherent to the breed and ya gotta live with it. No real fix

2. Dirty cooling system. Crudded up passages makes for poor heat transfer, crud in the rad fins restricts air flow. Crud in the passages just happens over time as the iron rusts, particulate drops out, gasket material/silicone breaks off and floats around, casting sand comes adrift, etc. Bugs, dirt, stones, leaves, etc are a fact of life as they impact the rad driving down the road. Best you can do is clean/flush the cooling system, clean the exterior of the rads.

3. Cooling system flow. Addressed as best a possible by GM in the final years of the design with higher flow pumps, dual stats, etc.....

4. Getting enough air into the radiator and out of the engine bay. Design of the truck makes it difficult. No real fix but upgraded DMax fan and custom clutch helps.

5. Restrictive stock exhaust. Causes higher egt's, which ends up in more heat load in the engine, which causes more load on the already taxed cooling system. Solution: open it up with an aftermarket system.

6. Turbo. Most accept that the GMX series is too restrictive. Meh, I've never had that problem and I've chassis dyno'd 270 to the wheels and towed my 35 foot trailer from the west cost to the east in one shot (well, except for a week stop in Ellensberg to instal the new Optimizer) with my "restrictive" GM8. But the rest of my truck is not exactly stock either...

7. Turbo management scheme and fueling. The factory program is basically designed for MPG and quietness. The truck was really meant as a MPG saver, not a heavy tower or worker, even though it was all GM had to offer in the diesel arena. Push it hard and teh MPG vs work demand results in some strange PCM behavior (ie: lots of fuel, lots of wastegate action) and heat is often the result. Re jigging the tables (reflash PCM/Chipping) or dropping in a TM changes quite a few things here....;)

That's real quick and off the top of my head, I could go on quite a bit more if I didn't hate "hunt and peck" typing so much.....:p

Now, that's all on just a stock truck.

Start "turning up the wick" and things begin to get a lot hotter and a lot harder to deal with real fast.......