Note: The following was posted on a Hummer Forum, but alot of what follows will obviously work on any Cummins conversion.
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Feeling like I haven't spent enough time and money on my H1 in the last year, I embarked on a new project to lower the body lift. The inline engine is tall and a 4" or so body lift is required to clear the valve cover (and still have the oil pan above the frame rails)
Lowering the body wont affect the ground clearance for most obstacles, I still have 20" under the differentials, I'll just be able get in and out of the cab a bit easier.
To do this is going to be some work. It means I need to lose the large stock fan and have some work to the valve cover. They are in the way of lowering the body 2". It also means a new radiator. $750 later I have a new radiator and electric fan installed.
While my Cummins fan is fine, I didn't want to trim it down and was a little hesitant on the electric fan, but the consensus from Dubvee and my mechanic buddies said it's a good way to go, so here I am.
The fan is a Flex-a-Lite 188
Flex-a-lite 188 - Flex-a-lite Black Magic Xtreme Series Electric Fans - Overview - SummitRacing.com
It pulls a monstrous 3300 cfm. It also exactly fits my new radiator, perfect on the height, and 1" narrower on width, leaving me room for my adjustable temp probe.
With the fan off, it took an hour for the truck idling in the driveway to hit
196 degrees. (it's got a 190 degree thermostat). The temperature read 193 with an infared on the output of the thermostat housing, 163 at the bottom hose (return) of the radiator.
On an 82 degree day, with the fan on for around 5 minutes, the bottom of the radiator dropped from 163 degrees to a cool 91 degrees. The entire radiator becomes cool to the touch, it's weird.
The fan thermostat is adjustable from 160 to 240 degrees, and my truck runs around 190 or so (dash reading) with the fan cycling on every 5 minutes or so for about 30 seconds.
I'll probably install a switch that will let me turn it on (apply 12v to the green (a/c) sensor wire, or interrupt the ground to forcefully turn it off (deep water fording so I don't break the fan blades).
FWIW, the Cummins fan rarely cycled on, so there weren't any overheating issues and I found that toggling a wire to ground would forced the fan clutch to fully engage. (It has a computer controlled electric clutch that gets pulsed to ground - to vary the speed). This electric fan can drop the temperature way lower, but that probably has more to do with a better shroud as the Cummins fan looks noticeably larger.
I found a valve cover on ebay for $40, I'll lower the oil spout and relocate the CDR'ish box atop it, that's the last remaining issue (i can readily see) to lowering the body. I'll need to check the exhaust downpipe.
The aluminum body is held on by 6 bolts, so lifting up the body is a fairly simple task, you just need to be aware of some lines that you don't want to overstretch. (so disconnect, or be careful)
Hummers should have come with a rear mounted hinged hood, it makes access to a lot of things a whole lot easier.
Pics taken with the side panels removed for easy engine access.
Changing a belt or the water pump couldn't be easier.
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