Hayden fan drive

[Slugblaster]

On the Heath diesel page they say with the Hayden severe duty fan drive with your factory metal fan that a dual thermastat cooling upgrade is not needed. What do you all think about that? I just purchased a 3000lb trailer and I need to cool down on the grades.

[More Power]

Increasing coolant flow from 87-gpm to 130-gpm was accomplished in the 1997 model year, primarily to reduce the possibility of cylinder head cracking.

That said, most who install the upgrade kit also report improved cooling. It is beneficial for those who tow and/or anyone who experiences high engine temperatures with their 6.5 diesels.

Discussions about twin thermostats in the various SAE papers include redundancy and reduced cavitation as the primary benefits of using two thermostats. The combination of hi-capacity water pump and twin t-stats allow for a 74% increase of coolant flow through the engine block/heads and a 9% coolant flow increase through the radiator.

MP

[Dihrdbowti]

My understanding (and I'm a newb to diesels) is that the 97+ cooling mod (dual t-stat and HO waterpump) is to flow more water within the block to reduce hot spots, not necessarily to keep the overall system cool.

[Kennedy]

As MP stated, first we need to stabilize the internal temps, and improve the flow of coolant through the radiator.

It is also my belief, and will remain so until proven otherwise, that the Hayden clutch is simply a Borg Warner unit built to OEM spec. No special calibrations, and no special design as mentioned in a generic statement on their site.

Ronniejoe and I discussed this at length at my Open House. Ronnie even has an OE clutch cut apart showing that it is indeed built the way that Hayden claims is special about theirs.

[Kennedy]

Just FYI, I've added the Hayden clutches to my line. Still say they are OE spec, but for some, it seems a good OE unit is all it takes and replacing their old worn out clutch does the trick.

[Dihrdbowti]

John where were you last month when I upgraded to the Severe Duty?? just kidding. I upgraded to the 97+ OEM unit with Duramax composite blade and my fan would kick in between 210 and 215. I swapped to the Severe Duty (as I am a little strapped for cash right now and would love to have the JK clutch) and the fan now kicks in between 195 and 205. And as far I can tell by just a visual it looks identical.

[rj]

Dihrdbowti...

Welcome to the DP, its good to see another Reno member.

[Scooby]

The early kick in of the severe duty clutch should improve the overall performance of the cooling system. Many newer big diesel trucks have what they call a LOW FLOW cooling system, in which the coolant flow thru the block and heads is much slower than on older models. You can look at the size of the water hoses and see that- many 1 1/2, - 2" !! Much smaller than even a 6.5 has. The key is to have large temp drop thru radiator, using multi-pass, and also have the fan clutch (lockup on many) kick in at 180 . The slower moving coolant has more time in both the engine to absorb the heat, and in the radiator to have the heat removed. Increasing the airflow with a better lockup, and having that increase occur at lower temperatures, will result in better cooling. How much better is the real question for our 6.5's .
I have seen gassers running with no tstat actually score pistons due to extreme block temps cause the water is running thru so fast it doesnt have time to absorb the heat. Put in a tstat (slows water down), and everything works properly.

Thats my .02

[CleviteKid]

IMHO: the modern "low flow" coolant system has only one goal: reduce power loss to increase fuel mileage. The manufacturers are cutting it close on cooling to up the CAFE level to sell more trucks. This is good for them, but not necessarily good for us. More flow = better cooling ability - fundamental heat transfer technology.

Dr. Lee :cool:

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