M936 Overheating

[ccbamatx]

Hey guys...

My M936 is overheating. I noticed that the fan is not turning.

So... I guess I need a new fan clutch and, in the mean time, install the clutch override lockup bolts as discussed in the TM.

Can one of you give me some direction on replacing the clutch?

Thanks,

 

[Suprman]

Bypass the shutterstat and see if the fan/clutch engages.

 

[juanprado]

Which Engine? I assume NHC250 since you have the bolts?

 

[ccbamatx]

Bypass shutterstat... OK

Regarding the engine....

It is a 1990 BMY M936A2 6x6 Wrecker with a Cummins 6 Cylinder Turbo Diesel Engine.

Which engine does that give it?

 

[603hellmutt]

8.3L 6CTA, only the NHC 250 has the lockup bolts for the fan clutch.

 

[Tinstar]

Bypass shutterstat... OK

Regarding the engine....

It is a 1990 BMY M936A2 6x6 Wrecker with a Cummins 6 Cylinder Turbo Diesel Engine.

Which engine does that give it?

Sounds like some time with the TMs is needed.

 

[440Duster]

We I agree that spending time reading the TM's is valuable, some things are not addressed indepth enough. I have a M925A2 that started getting hot this summer.Since there was coolant flow through entire system and the fan actuated as it should, I ruled out a thermostats being stuck closed and elected to replace the water pump. After completing that and noticing that the pump I removed seemed to be issue free, I decided to remove and check the thermostat. I discovered that the thermostat had been removed which explained everything. I ordered and installed both the thermostat and the seal...problems solved.

 

[74M35A2]

Maybe it is not overheating also, and the gauge/sender is flunky. Check for bubbles getting pushed into the coolant, and coolant in the oil (drain 1" of oil from pan). Feel the hoses going in and out of the engine, and temp of the heater, it can tell you more about what is hot or cold with the system, same with flow. Water pumps, coolant, thermostats, belts, and Cascade (flush) are cheap and easy to do vs major engine damage.

 

[1 Patriot-of-many]

Remove the line going from the shutterstat to the fan, Get the engine up to 210 or so on the gauge, use an air compressor and air blower attachment put to the line, if the fan runs, it's either the shutterstat or one of the elbows is clogged up..Or as Suprman said hook both airlines together to rule out fanclutch ect... An elbow with 1/4" flares or 1/4 inch t with cap http://www.steelsoldiers.com/showth...e-shutterstat-fails-cheap-fix-for-emergencies .... I went and bought a shutterstat because my fan on my 923A2 stopped working. Was about to start swapping them out, pulled the elbows off the old shutterstat and noticed one of the elbows appears to have a filter in it, looked completely clogged up. Bought an elbow, tada..... Not the shutterstat.

 

[Csm Davis]

Are you 100% it is over heating? I trust my shutterstat more than the gage because the senders are known to read high when they go bad. Check it with a IR gun to get an accurate temperature.

Sent from my SM-G900V using Tapatalk

 

[Tinstar]

We I agree that spending time reading the TM's is valuable, some things are not addressed indepth enough. I have a M925A2 that started getting hot this summer.Since there was coolant flow through entire system and the fan actuated as it should, I ruled out a thermostats being stuck closed and elected to replace the water pump. After completing that and noticing that the pump I removed seemed to be issue free, I decided to remove and check the thermostat. I discovered that the thermostat had been removed which explained everything. I ordered and installed both the thermostat and the seal...problems solved.

I was actually referring to the fact that the OP did not even know what size engine was in the truck.

 

[ccbamatx]

Well... thanks to the 98% of you who have given me very helpful answers.

I was 90% confident that it is a Cummins 8.3 L turbo inline 6 diesel engine with 240 hp... thank you hellmutt for confirming that.

What I did not catch was that that particular engine does not have lockup bolts for the fan clutch.

Unfortunately, my maintenance guy almost burned it up when I drove up...

I am certain it is overheating... it was dripping coolant underneath and boiling up through the coolant pressure cap on the surge tank.

So... now the truck is stuck 30 miles in the back country and 200 miles from me.

Again... I really appreciate those of you who have helped with your straight answers.

I was hoping that with lockup bolts, I could engage them and just drive it out, back to the shop.

Without the lockup bolts, do any of you guys have a suggestion on how to drive it out, or am I stuck with repairing in the field?

 

[Suprman]

Have you bypassed the shutterstat so air always goes to the fan clutch yet? To verify that it is indeed a bad clutch.

 

[74M35A2]

Once fully cooled off, you can drive it a short way until it gets warm. Like said above, bypass the shutterstat and you may be good.

 

[ccbamatx]

Not yet... I am going back out this weekend.

What supplies am I going to need to bypass the shutterstat? (Is that what the TM is calling the fan clutch thermostat?)

 

[74M35A2]

If it is just a fan issue, you should be fine, just get on the road and drive at a good rate of speed. It it is a thermostat, grab one from a store and head there with some jugs of water and tools. I don't see it being harder than either of these.

 

[adamsoffroadperformance]

unless its a hot humid day i'm surprised it's getting hot. even on the hot days mine was lucky to kick on or even get the temps close to need to kick on when pulling the hills loaded. granted offroad is slower moving but unless you have to run it hard I wouldn't think it should get that hot.

 

[Csm Davis]

Well... thanks to the 98% of you who have given me very helpful answers.

I was 90% confident that it is a Cummins 8.3 L turbo inline 6 diesel engine with 240 hp... thank you hellmutt for confirming that.

What I did not catch was that that particular engine does not have lockup bolts for the fan clutch.

Unfortunately, my maintenance guy almost burned it up when I drove up...

I am certain it is overheating... it was dripping coolant underneath and boiling up through the coolant pressure cap on the surge tank.

So... now the truck is stuck 30 miles in the back country and 200 miles from me.

Again... I really appreciate those of you who have helped with your straight answers.

I was hoping that with lockup bolts, I could engage them and just drive it out, back to the shop.

Without the lockup bolts, do any of you guys have a suggestion on how to drive it out, or am I stuck with repairing in the field?

I bet it isn't getting to hot, what did the temperature gage read when it was pushing out antifreeze? I have seen my M931A2 push out fluid and it is never overheating the gage and my IR gun confirm this. The fan wasn't running when it did this. Old saying Trust but verify.

Sent from my SM-G900V using Tapatalk

 

[74M35A2]

Leave the cap loose/off, let it boil, it will not exceed 212F. Keep adding water. Change the stat when you get there. It should be fine and not need fan if moving briskly. Buy a 12v electric fan and strap it to the front of the radiator, run the wires back to one battery, run it continuously, there are several things you can do.

 

[1 Patriot-of-many]

1/4 inch flare ends elbow or t with cap...... disconnect lines from shutterstat, connect to t or elbow. 1/4 inch flare ends..... Fan will run continously if it's the shutterStat or elbow clogged up.