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!!!

 

[jaws4518]

So far, I have a bad water pump and questionable thermostats to say the least. I was going to test the thermostats but the rubber seals were gone and only fragments were left. I just replaced them. I drained the coolant completely. It looks good and there is very little signs of corrosion inside the thermostat housing. In the process of putting everything back, then I will go down the check list again to see what else need attention. I believe my radiator and rear cooler is clean now. I washed them out thoroughly. Never got a high temp light on the display when all of this was going on? Clutch fan seems to be working normally. I will followup with the results later today. Please elaborate on the high temp sensor light. Is that the transducer on the side of the thermostat housing. I haven't look at the TM with any detail yet. I will be following up on this repair after fact. I don't like doing it that way but replacing the water pump and thermostat is pretty straight forward.

 

[Ronmar]

Yes I believe that is the high temp switch on the side of the thermostat housing. Drives the dash high temp light at 230F…

 

[jaws4518]

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…

I thought I would go down the list of items you mention. The fan clutch is not locked as you mention above. It is free-wheeling despite the ignition being on or off. It will lock up when the air pressure bleeds off.

 

[Ronmar]

Hmmm. So when you turn off the ignition sw(or the ECU calls for fan @205F), you should get a woosh from under the passenger dash as the fan solenoid valve de-energizes and releases the fan clutch air and locks up the fan clutch. If this isn’t happening with power off, and the fan clutch only engages when air is bled off, it sounds like your fan solenoid valve is bad. whenever the engine is running you should be able to unplug the fan solenoid plug under the dash to engage the fan.

Got just the thing for that…

CallmeColt and I R&D’d this as a cost effective alternative solenoid valve to replace the fan clutch and power divider solenoids just ordered a new one for my pac-brake install from automation direct on friday. Was on the front porch this morning. I think he was offering a kit with plug and fittings. @CallMeColt ?

 

[jaws4518]

Hmmm. So when you turn off the ignition sw(or the ECU calls for fan @205F), you should get a woosh from under the passenger dash as the fan solenoid valve de-energizes and releases the fan clutch air and locks up the fan clutch. If this isn’t happening with power off, and the fan clutch only engages when air is bled off, it sounds like your fan solenoid valve is bad. whenever the engine is running you should be able to unplug the fan solenoid plug under the dash to engage the fan.

Got just the thing for that…

CallmeColt and I R&D’d this as a cost effective alternative solenoid valve to replace the fan clutch and power divider solenoids just ordered a new one for my pac-brake install from automation direct on friday. Was on the front porch this morning. I think he was offering a kit with plug and fittings. @CallMeColt ?

That seems to be the case. I'm going repeat the test procedures again as you have line out. After that I will start the engine and unplug the fan solenoid. So, when I start the engine for the first time this morning the fan clutch will be engaged for a minute or so until air pressure is built up. After a couple of minutes at low idle, the engine goes into a higher idle for a minute or so.., and the fan clutch seems to engage to some degree, then it seems to disengage again when the auto idle comes back down. I will go pull the passenger panels to observe what is going on when I repeat this. I should hear a woosh when the fan switch is turned off. It does sound like I have a bad solenoid. Lastly, I will pull the solenoid plug to confirm this. I wonder if this condition caused me to loose the water pump? The water pump did not start leaking badly until 500 miles later after high heat conditions. In addition, I must have a bad high-temp switch too. I think these issues were overwhelming for the VFD that I purchased the truck from. They are so used to the M800/900 series trucks. They said the cab over just doesn't work for them in fighting fires from the front of the truck. I will report back in a bit.

 

[jaws4518]

Hmmm. So when you turn off the ignition sw(or the ECU calls for fan @205F), you should get a woosh from under the passenger dash as the fan solenoid valve de-energizes and releases the fan clutch air and locks up the fan clutch. If this isn’t happening with power off, and the fan clutch only engages when air is bled off, it sounds like your fan solenoid valve is bad. whenever the engine is running you should be able to unplug the fan solenoid plug under the dash to engage the fan.

Got just the thing for that…

CallmeColt and I R&D’d this as a cost effective alternative solenoid valve to replace the fan clutch and power divider solenoids just ordered a new one for my pac-brake install from automation direct on friday. Was on the front porch this morning. I think he was offering a kit with plug and fittings. @CallMeColt ?

Ok, I tested everything forward and backwards and the air to the fan clutch is not releasing. I unplugged the solenoid valve while the engine is running then cut the engine to see if the clutch was engaged? Nope! The fan still spins freely until the air pressure bleeds off. Yeah, bad solenoid valve.

What is the other valve for? I tried to find the diagram in the TM but haven't found so far. Out of TM research practice. Will order the alternative you mention.

 

[Ronmar]

If you have 2 valves in there, you have a 6X truck? That second solenoid is for the power divider lock-up in the middle axle when you enter mode...

 

[jaws4518]

If you have 2 valves in there, you have a 6X truck? That second solenoid is for the power divider lock-up in the middle axle when you enter mode...

Ok, I know which one is clutch fan valve now. I touched the bottom and released the air. Now the fan is engaged continuously. Should I replace both or will the new one stack together with the old? I don't guess I have had a cooling fan since day one?

 

[GeneralDisorder]

Ok, I know which one is clutch fan valve now. I touched the bottom and released the air. Now the fan is engaged continuously. Should I replace both or will the new one stack together with the old? I don't guess I have had a cooling fan since day one?

They are a known failure point so I would replace both. The new ones don't stack I don't think. The MTV power divider is only used when you select MODE on the Allison control panel.

 

[Ronmar]

The new one i show in the video will NOT stack with the old ones on the truck, but they do stack with each other. Automation direct sells the stack kit(hardware and an o-ring) listed under accessories when you look up the valve, ~$3. I Just stacked a new solenoid onto the one i showed in the video last night, to use for my exhaust brake. add a couple 1/8" NPT male to 1/4" pushlock fittings and it should be a pretty easy project to replace them both...

These trucks do not ram air cool very well... That and the 2:1 hubs spinning the engine well past peak torque at speed(like driving with an exhaust brake on), a working fan is a must...

 

[jaws4518]

The new one i show in the video do not stack with the old ones on the truck, but they do stack with each other. Automation direct sells the stack kit(hardware and an o-ring) listed under accessories when you look up the valve, ~$3. I Just stacked a new solenoid onto the one i showed in the video last night, to use for my exhaust brake. add a couple 1/8" NPT male to 1/4" pushlock fittings and it should be a pretty easy project to replace them both...

These trucks do not ram air cool very well... That and the 2:1 hubs spinning the engine well past peak torque at speed(like driving with an exhaust brake on), a working fan is a must...

10/4! I ordered the AM-3224 manifold which will allow me to cluster (4) valves together. I got all the supporting hardware and gasket parts to complete a 2-3-4 solenoid valve configuration. Got to go all new, plus room for expansion. Found two pair of cut wires labeled TL50. Got to look those up in the TM wiring schematic/diagram. The last multi-pin connector was resting at the bottom of the passenger control box compartment. I have no idea where it goes? There is no empty interface that it would go to. The (2) two pair leads were stuff in the back. That other cable was stuffed under the passenger seat. Radio maybe?

 

[MatthewWBailey]

10/4! I ordered the AM-3224 manifold which will allow me to cluster (4) valves together. I got all the supporting hardware and gasket parts to complete a 2-3-4 solenoid valve configuration. Got to go all new, plus room for expansion. Found two pair of cut wires labeled TL50. Got to look those up in the TM wiring schematic/diagram. The last multi-pin connector was resting at the bottom of the passenger control box compartment. I have no idea where it goes? There is no empty interface that it would go to. The (2) two pair leads were stuff in the back. That other cable was stuffed under the passenger seat. Radio maybe?

View attachment 933188View attachment 933189View attachment 933190

I had that same connector on mine stuffed under the passenger seat. It was crudely wired back to 24v ignition terminal under the panel cover, no fuse. Deleted.

 

[Ronmar]

Yea, thats the radio power cable.

the single solenoids are modular so you can stack as many as you want together. I got another one for an air horn but want to build a new base before I fit that one to the group…

 

[jaws4518]

Yeah, 10/4 on that. I thought one additional valve expansion would be good but you have to build in multiple of 2 so I picked the 4 valve option. I'm going to replace the existing and go with two with the possibility of four. Here are the part numbers to complete that task. My cost was $154.00 shipped.

Correction on parts. Somehow the AutomationDirect tech thought I was stacking AM32XX stuff. The stacking screws (AVP-31KIT) do not come with the solenoid valves.

ME 14-18N (5 pack stab-in 90 degree elbow air line connectors) Qty (1)
MS 14-18N (5 pack stab-in strait 1/4 air line connectors) Qty(1)
AVP-31C1-24D (2)
AVP-31KIT (1)
AVP-31BKT (2)



This was ordered from AutomationDirect.com

 

[jaws4518]

I had that same connector on mine stuffed under the passenger seat. It was crudely wired back to 24v ignition terminal under the panel cover, no fuse. Deleted.

Yeah, the radio cable was terminated into computer type (high-voltage) pull-apart shell. Then there was a set of wires labeled TL 50. I need to TM that and see what it is and where it goes. Other than those two pair, that's about it. I need to search the forum on how members have utilized unused circuit breakers / relays for other purposes.