Running 37 humvee tires with the 6.2

[welpro222]

I am running 37 BFG Humvee tires on my suburban with a 6.2 non turbo/th400/np208/14 bolt FF 4.10. It seams to drive well in town and on flat freeway at 60-65. But when I hit a decent hill it slows down and if the hill is a long run it starts to heat up to 215-220? I have a Autometer temp gauge installed right before the thermostat in the crossover housing. Most of the time it stays at 185-190.

Here are some other specs: 180 degrees robertshaw(prestone) thermostat. I did use a 190 robertshaw before with same results. A cleaned 4 row stock GM radiator. Standard water pump (unknown condition, since I bought truck). Fresh coolant 50/50 green stuff.

Is this normal? I still have my dummy light hooked up too and it never came on (not sure what temp is comes on anyways) Is the temp after the heads that much hotter then the temp in the heads?

Also I have pulled my lawnmower behind a small utility trailer and it will slow my truck down pretty good on any incline and heat up faster. I realize the engine I run is pretty powerless, but I want to be able to load up with my camping and hunting gear and go over the pass without overheating regardless of my speed.

 

[rsh4364]

With your gears and tires you are spinning around 2200 rpms at 60 and 2400 at 65.Not really way to high,I would try a coolant additive like Water Wetter or Purple Ice first,they claim 20-22 degree drop in temps.I would deff. add a trans cooler and trans temp. gauge.The trans. might be running hot and transferring the heat to the coolant.

 

[welpro222]

I guess my point question is: Is this typical for this combo? How about those who run 37 humvee tires on the M1008 with 4.56 gearing?

 

[welpro222]

I have a aux trans cooler

 

[rsh4364]

I have a aux trans cooler

That's a good thing to have.I would try the coolant additive first.Our radiators not only cool the coolant but also the engine oil and trans. fluid.If the additive doesn't help try increasing fluid capacity of trans. and engine oil.Deep trans pan and larger oil filter may help.A trans.temp gauge is nice to have.I like the derale 14202 trans.pan adds almost 4 qts to a standard 400.or 1qt 3 ozs. to a true th400 HD trans. And I use the 2 qt. engine oil filter to add an extra qt. of engine oil.Also that trans. pan has a drain plug and a bung hole for trans.temp sending unit.

 

[Chaski]

I tried 4.10's in my GMC pickup contraption on 37's. It was not a happy combo. I have a 700r4, OD was worthless except on flat land. I went to 4.88:1 gears, and it is about perfect. The 4.88:1 gears put me exactly where I would be with 4.10:1 gears and stock sized tires. As for your coolant temp, I'm not positive, but if

You are lugging up a hill at full load your water pump may not be turning fast enough for the heat being produced. I can get my temprature gauge to climb a bit in triple digit heat pulling a grade. That is with a new radiator, thermostat, water pump etc. However my fan clutch is toast, and probably the reason for my temp climb. Without an OD transmission I think 4.56:1 gears are perfect, 4.88:1 is also good, if you don't do a bunch of freeway travel.