I've never seen my m1088 transmission cooler fans come on

[Reworked LMTV]

Anyone with an M1088 see their trans cooler fans come on? I don't tow, so maybe the temp has not gone up enough to trigger. Radiator gets hot. Maybe needs new relay or thermostat?

 

[Kbarnes0]

I'm interested in this also. It seems they have so much cooling it would need to be operated for extended periods of time with major load.

Even with 18k in my dump truck I never noticed them coming on.

 

[Floridianson]

Yea mine comes on if the temps get high enough when I am off road. Never heard it when on highway. If I remember if you disconnect the wire from the sending unit on pipe and use the fording switch the rear cooler fan should come on. Thought cant' remember if you were running and the engine fan comes on and you use the fording switch it will shut off engine fan and also bring on the Trans. cooler fans.

 

[Ronmar]

Even though it has external coolers the trans fluid still passes thru a heat exchanger up under the front of the engine. You have to exceed the radiators capacity to remove heat from the trans(and engine) to get warm enough to engage the secondary cooler...

or yours is broke not sure how the secondary is triggered or how to test it...

 

[ckouba]

Looking at it recently, the FWD heat exchanger appears to be liquid-to-liquid. The failure mode of that would be clogged/compromised passages or reduced flow through the cooler (bad pump? although you would likely have other problems if that was the case).

I haven't stressed mine at all but it has never come on in the couple hundred miles I've logged. When I bought it, the seller specifically told me he was thinking of just deleting it as there is enough cooling capacity to address the heat load for the duty cycle of a camper. I chose to keep it... I'm not willing to roll those dice, and it was easy enough to relocate.

 

[JD4044M]

Not Military but my TH400 Automatic transmission runs cool all the time thru it's cooler only. It only gets into the Yellow Range when I pull a long steep hill and have to use a heavy throttle to keep the speed up. I have a manual cooling fan I can kick on if needed. You do want your transmission warmed up some to work better. Same with Water Temps.

 

[Ronmar]

Looking at it recently, the FWD heat exchanger appears to be liquid-to-liquid. The failure mode of that would be clogged/compromised passages or reduced flow through the cooler (bad pump? although you would likely have other problems if that was the case).

I haven't stressed mine at all but it has never come on in the couple hundred miles I've logged. When I bought it, the seller specifically told me he was thinking of just deleting it as there is enough cooling capacity to address the heat load for the duty cycle of a camper. I chose to keep it... I'm not willing to roll those dice, and it was easy enough to relocate.

The liquid to liquid isn't likely to clog in a sealed system. The worst failure mode for the liquid to liquid heatex would be for it to leak coolant into the trans fluid, which basically wipes out all the trans clutchpacks... if I was making a 1088 into a camper I think I would look at going with the liquid to air only. About the only advantage of the liquid to liquid is to add some heat to the trans if you are operating in extremely cold conditions.