M1165 Coolant System Upgrades

Diablo

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I have a 2007 M1165 non-REV that, true to form, is constantly running hot. Since I will not be putting JP8 or anything other than #2 Diesel in it, I'm looking to turn the temperature down a little bit. The coolant stack has been separated and pressure washed. I have installed a new 180-degree thermostat. I have flushed the entire system four (4) times. I'm seeing reservoir temps of 205-210, radiator temps at the upper radiator hose of 230-235, and thermostat housing temps of 210-220, as measured with an IR thermostat. The radiator and system is flowing well. When the fan kicks on, it drops it down to 180-190 all around. However, within 3-4 minutes of the fan shutting off, it's all right back up to the previous temperatures.

In my research, I've found a few things that can be done to bring the temps on the 6.5 NA or Turbo into more reasonable temperatures:
  • Replace the OE water pump with the, high flow, balanced version - GM PN: 251-603
  • Replace the fan clutch with a Hayden 2886 Thermal Clutch (non-Electric Duramax), eliminating the thermal switch, TDM and Cadillac Valve
  • Replace the fan with a GM PN: 15-80690 from the Duramax.
Replacing the fan is where things get... wrong. 15-80690 is a 21" fan, where, it appears the M1165 OE fan is only 19.5". And there is definitely not enough room to stuff an extra 1.5" in the fan housing. As a matter of face, it appears the current fan has actually contacted the housing a few times, already. On the passenger side of my truck, there is only about 0.125" of clearance between the fan blades and the shroud.

I have found a few places that have kits for H1s, and a few others with kits for HMMWVs. However, they are not in stock, won't fit the ECV/REV trucks, or are ludicrously expensive.

Has anyone attempted these conversions? If so, what fan did you utilize? Did you source your own parts, or did you go with someone's kit?

Please advise.
 

Mogman

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I had to cut down the fan on my conversion, I used an early LBZ fan on my LMM and a Kodiak fan clutch.
How are you getting around the fact that the Duramax clutch is the threaded type and not the 4 bolt type?
I think most are using a late style 6.5L civy setup.
 

Mogman

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But on the other hand if the fan is cooling it off then what is the problem?
You might try another fan thermal switch to see if it comes on earlier.
I do not think anything you can add will move as much air as the factory fan
 

Diablo

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I had to cut down the fan on my conversion, I used an early LBZ fan on my LMM and a Kodiak fan clutch.
How are you getting around the fact that the Duramax clutch is the threaded type and not the 4 bolt type?
I think most are using a late style 6.5L civy setup.
What means did you use to cut down your fan?

The 251-603 Water Pump is designed for the later style, spin-on clutch, like the Hayden 2886. It does move the fan forward about 0.75", though.

Initially, I was thinking about putting a resistor in-line with the current thermal switch to bring the activation temperature down, but I'm not a fan of adding additional heat to the under-hood electrical. Nor adding an additional point of failure. It also still leaves the Cadillac valve as a potential point of failure.

While the current fan system does work exceptionally well when it's engaged, it free-spins when it is not. The Hayden 2886 is a 20/80 lock-up. It always runs at twenty-percent lock unless it's engaged, then it only runs at eighty-percent, which doesn't siphon quite as much horsepower as the OE system.

The final positive is, by switching to this setup, it eliminates additional strain on the power steering hydraulic system. This allows the power steering system to be more efficient when operating in hot weather. (Which is about all I have here in east Texas!) The basic math I've (by "I've" I mean, "my father the ME with all kinds of stupid computer programs...") done suggests a loss of
This has, apparently, been a go-to cooling upgrade for 6.5T and NA pick-up trucks since the upgraded 251-603 and clutch came out. They don't use the smaller shroud, though, so no need to cut down the fan.

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Mogman

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The thermal switch is just a switch on or off, a resistor will do nothing except make it not work at all.
I used a large pair of snips to trim the fan.
You cannot decide what to do based on what the pickup owners did, the HMMWV does not draft enough to stay cool at highway speeds the pickup does so that 80% may not be enough.
the "stress" you talk about is minimal only raising the return pressure buy about 100 PSI, no sweat for the HMMWV as thousands have proved.
But it seems you are determined to go through allot of expense and time to get marginal if not negative results.
When did they move Kerrville to East Texas?
The first thing I would do is try replacing the thermal switch and possibly the IR thermometer you are using
 

Diablo

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The comment about it being an upgrade for the pick-ups was anecdotal. There are actually several "companies" selling this same setup as a kit for the HMMWV and H1. But, they are charging between $600 and $2K for it. I have only found four (4) complaints about these "kits" and, as best I can tell those are made by people who should only be allowed Fisher-Price tool kits...

I'm alright with spending a little money and time investigating modifications and upgrades to our monsters. One of my companies actually prototypes various bits and pieces for USSOCOM and NSW CRANE. We haven't worked with the HMMWV platform, really, though. If it works, GREAT! I'll write up the modification/upgrade, and give it to everyone so they can do it themselves without having to purchase a kit. If it doesn't, it's just a few more hours to get it back to where it is, now.

As for Kerrville it's still right where it's always been! I still have a house there, but my work requires me to be on international flights on very short notice, and most of my CONUS work is in Austin, Houston, and San Antonio. So, I have a place in the thriving metropolis of Weimar, Texas. Eighty clicks west of Houston.

Hell man, we're practically neighbors!

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Mogman

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Despite a couple unsubstantiated claims I don't think anyone has successfully switched to electric, it would take a VERY powerful electric fan to even come close to the air moving capability of the belt driven fan, again despite what the fan manufactures claim.
Someone may come in here and quote the HP but the belt driven fan draws allot of HP, (10-15?) physics dictates you would need close to that amount of HP in the electric motor
 

911joeblow

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A cooling balance kit is in order! Those temps you are reading are system temps but the rear two cylinders are running far hotter. The kit will improve the overall performance of the cooling system and keep the rear from overheating.
 

Diablo

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I have acquired all of the parts listed in the original post, and will be installing them tomorrow. Finally got the AC in the shop working as it is supposed to. (Two HVAC companies couldn't figure out that a 30A breaker isn't quite enough for a 10-Ton unit that pulls 33A-50A...)

Planning on documenting everything as I go. If all works as it should, I'll write it all up and get it pushed out here.

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Diablo

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A cooling balance kit is in order! Those temps you are reading are system temps but the rear two cylinders are running far hotter. The kit will improve the overall performance of the cooling system and keep the rear from overheating.
I actually just ordered one of your Cooling Balance Kits last night/this morning. I'm looking forward to having it. It's the first actual solution to the overheating issues I've seen.
 
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