1083A1 Engine Cooling Issues

[jaws4518]

So, it has been hot here in West Texas this summer. We traveled to Waco to pick up a 50DLA tag-along trailer. It was 95+ all the way and half of the way back ( 350/400 ) miles round trip. We kept the engine temp no > 230 degrees. Last week was hot and unusually humid for this region of the state. Never got a coolant temp light though.

When does it kick in?

I'm talking 40 - 45 miles per hour, sometimes 50 until things heated up. It was a long day but we made it. The LMTV was impressive despite the unknowns for which we were faced with not knowing its past. You hate to destroy something because you are willing to take that chance. We were taking note of every sound to say the least... Anyway, it was a beneficial experience from start to finish. We prepped for the worst. We were ready to change a tire on the highway. We came through without incident...




So give me your best advice for what you have experienced and learned. I will do the same. I will digest old threads that touch on this subject.

Thank you.

 

[Ronmar]

So 3126, high temp light should be ~230F either controlled by the ECU or a thermal sw on the thermostat housing…

was your fan cycling/did it engage above 205F? With air tanks full(dryer purges), shut down the engine and with the ignition switch off, reach in under the front of the truck and see if you can rotate the fan. Tanks full and ignition power off the fan solenoid should remove air from the clutch and it should be locked up. Turning on the switch should release the fan clutch and the fan should freewheel…

cooling is typically about flow. You need airflow thru the radiator and coolant flow thru the rad. One good place to look is for temp drop across the radiator top to bottom. A typical rad will drop ~10F from input to output. If you have more drop than that from top to bottom, then you probably have inadequate coolant flow thru it( lower coolant volume more easilly cooled by the radiator).

If you have less than 10F drop, then you probably have reduced airflow or problems with surface area(dirty/coated air or water passages(not transferring heat).

these use a bypass thermostat. It has two discs, one opens to the radiator and closes the bypass port. If that has an issue, it may not fully close the bypass port and not force all the coolant thru the radiator. Loose belt or water pump issue could also reduce flow.

If you have low delta, did the fan check above work OK, at RPM the fan kicking in should have a pretty substantial roar… you should be able to hear it at the high temps you were running by using the fording switch(upper left dash) to disengage and re-engage the fan.

have you flushed out the radiator and intercooler air passages?

lastly how is the rolling drag? How were the brake drum and hub and axle temps. Drag = fuel and heat, not to mention tooling along above peak torque is like driving with an exhaust brake on…

 

[Suprman]

Its hard to visually see sometimes but the radiator fins can get clogged up with dirt and debris sometimes a good pressure washing clears it out.

 

[jaws4518]

So 3126, high temp light should be ~230F either controlled by the ECU or a thermal sw on the thermostat housing…

was your fan cycling/did it engage above 205F? With air tanks full(dryer purges), shut down the engine and with the ignition switch off, reach in under the front of the truck and see if you can rotate the fan. Tanks full and ignition power off the fan solenoid should remove air from the clutch and it should be locked up. Turning on the switch should release the fan clutch and the fan should freewheel…

cooling is typically about flow. You need airflow thru the radiator and coolant flow thru the rad. One good place to look is for temp drop across the radiator top to bottom. A typical rad will drop ~10F from input to output. If you have more drop than that from top to bottom, then you probably have inadequate coolant flow thru it( lower coolant volume more easilly cooled by the radiator).

If you have less than 10F drop, then you probably have reduced airflow or problems with surface area(dirty/coated air or water passages(not transferring heat).

these use a bypass thermostat. It has two discs, one opens to the radiator and closes the bypass port. If that has an issue, it may not fully close the bypass port and not force all the coolant thru the radiator. Loose belt or water pump issue could also reduce flow.

If you have low delta, did the fan check above work OK, at RPM the fan kicking in should have a pretty substantial roar… you should be able to hear it at the high temps you were running by using the fording switch(upper left dash) to disengage and re-engage the fan.

have you flushed out the radiator and inter-cooler air passages?

lastly how is the rolling drag? How were the brake drum and hub and axle temps. Drag = fuel and heat, not to mention tooling along above peak torque is like driving with an exhaust brake on…

I will follow what you have outlined above. I believe my fan is cycling but do I know that for sure? No! I have seen it idle then engage on startup while the cab is up. That doesn't mean much though... The fan off switch does work. I believe we can hear the fan fully engaged but it is nowhere near as loud as the M900 series truck. Everything needs a thorough checkout and flushing. My old school CAT mechanic/mentor has lined me out on all that you have mentioned. He also mentioned a sediment brick in the thermostat housing. Something like that anyhow? I've got check everything and do a full service. I will report back with the results. Thanks!

 

[jaws4518]

So 3126, high temp light should be ~230F either controlled by the ECU or a thermal sw on the thermostat housing…

was your fan cycling/did it engage above 205F? With air tanks full(dryer purges), shut down the engine and with the ignition switch off, reach in under the front of the truck and see if you can rotate the fan. Tanks full and ignition power off the fan solenoid should remove air from the clutch and it should be locked up. Turning on the switch should release the fan clutch and the fan should freewheel…

cooling is typically about flow. You need airflow thru the radiator and coolant flow thru the rad. One good place to look is for temp drop across the radiator top to bottom. A typical rad will drop ~10F from input to output. If you have more drop than that from top to bottom, then you probably have inadequate coolant flow thru it( lower coolant volume more easilly cooled by the radiator).

If you have less than 10F drop, then you probably have reduced airflow or problems with surface area(dirty/coated air or water passages(not transferring heat).

these use a bypass thermostat. It has two discs, one opens to the radiator and closes the bypass port. If that has an issue, it may not fully close the bypass port and not force all the coolant thru the radiator. Loose belt or water pump issue could also reduce flow.

If you have low delta, did the fan check above work OK, at RPM the fan kicking in should have a pretty substantial roar… you should be able to hear it at the high temps you were running by using the fording switch(upper left dash) to disengage and re-engage the fan.

have you flushed out the radiator and intercooler air passages?

lastly how is the rolling drag? How were the brake drum and hub and axle temps. Drag = fuel and heat, not to mention tooling along above peak torque is like driving with an exhaust brake on…

oh, no rolling drag. Hub temps are normal. All of my radiator(s) were dirty. I washed them out before we went but that was not enough for a 99 degree day on the road. I can't say that the clutch fan roars back to life when you turn it back on? The radiator is probably full of sediment. I will let you know what I find when I drain it this weekend. Today I notice that the alt belts are very loose. It is running normal temp in this 85-90 degree temp. Everything needs servicing!!!