Got my deuce yesterday - question about overheating

[kiotiugly]

Hi everybody-

Preface: I searched the overheating threads but didn't find exactly what I was looking for, so I was hoping someone could help me.

I just picked up my deuce yesterday (from a private seller) and drove it home). The drive was about 100 miles. For most of the trip, the gauge showed about 180-190. With about 10 miles to go, the gauge started jumping back and forth from 180 to 240 (or "pegged"). Then it stayed at 240.

I pulled over and checked - there was no sign of leaking coolant, etc. and the engine didn't smell hot (most of my trucks/tractors/etc. have that "hot coolant" smell when they overheat).

Anyway, I let it set awhile and then drove it the last 10 miles home. The entire way, the gauge remained pegged. Within 5 minute of parking it at home, I took the radiator cap off and put in a thermometer (there was just a little pressure on the cap when I opened it, but no gush). The coolant was at the correct level, too (same place it was when I started). The thermometer read about 150-160.

I didn't have a laser thermometer at home to check any where else last night. I'm planning on bringin one home from work today to check this evening. My question is, where is the best place to check? Is the temperature sending unit just on the manifold side of the thermostat? If the thermostat happened to get stuck closed (after I had driven it an hour and half), then would the top tank of the radiator cooled off and the truck was actually overheating?

Also - I found some threads that showed getting a T-stat and seal from NAPA - is there any difference between these units and ones that would be purchased from a supplier?

Again, I apologize if I'm beating a dead horse, I just didn't see where I should take a temp reading if the thermostat happed to be bad.

Thanks again for the help.

 

[Boatcarpenter]

The jumping back and forth from 180 to 240 would indicate to me an electrical problem in the circuit. Either the sending unit going bad or the gauge or some connection causing the gauge to get full juice and pegging it. In theory I believe the sending unit sends more or less current to the gauge as the temp increases or decreases. The gauge responds accordingly. Your engine can't possibly warm up and cool down that fast for the jumping to occur. You can download the TM and trouble shoot the system or put you multimeter on and check current while checking all connections (especially any grounds) and see what you find. You can go the trial and error route and install another sending unit and see if that fixes it. If not, get another gauge and try that. Never hurts to have spares around .
Mine did the exact same thing after about 1 mile having just bought the truck. Went back to the guy I bought it from, threw in a new sending unit and it has worked correctly ever since.
Good luck. I think you have a simple fix.
BC

 

[rchalmers3]

x2 the symptoms are electrical. Good of you to do the temp confirmation.

My suggestion is to look for a compromised contact on or leading to the temp sensor. Something loose that can swing or flap in the wind.

Congrats with your new rig.

Rick

 

[avengeusa]

yup, electrical is my guess also, but it is scary when that happens on any vehicle

 

[nosliw]

mine didn't get above 160-170 for the first few trips out, but now, slowly rises when warming up to 220 and stays there. load, no load, highways, it doesn't matter.

i'm hoping to throw in a new 'stat and see what happens. i may try a sending unit as well.

when i pop the hood, nothing SEEMS that hot. no coolant pushing out the overflow, no gurgling, no steam...



i dunnno

 

[DUG]

The gauge is only as good as the lowest bidder.

 

[steelandcanvas]

I agree with the rest...electrical. Check all your connections, including your grounds. Good luck! Good call checking the temperature manually! Cancels any doubt.

 

[neb4x4]

The "thermostat" on the multi-fuel is not even a thermostat in my book. It's a copper washer, built as a restrictor of flow, with a spring on it..... OH, A NOTE TO SELF, DON'T INSTALL BACKWARDS....... YOUR HEATER WILL NOT WORK!!! LOL!!! FOUND OUT THE HARD WAY AFTER REPLACEING ALL THE HOSES!!!

 

[kiotiugly]

I ran the truck last night for a couple of hours and it never got warm enough to open the T-stat. After running around the farm for a couple of hours, we drove over to a friends house and the warmest it ever got was about 160. The gauge in the cluster also read about 160. All of the connections looked good, but I didn't take them apart and clean/replace. I'm just gonna keep an eye on it for a while and keep the temp gun handy so if it happens again maybe I can diagnose.

Thanks.

 

[Boatcarpenter]

After reading your last post, it occured to me that your sending unit may be the problem. It may be sending correct information to the gauge up to about 180 degrees. Beyond that temp, the sending unit may be internally shorted and sends full current to the gauge, causing it to bounce. It would be interesting to see if the "pegging" occurs again when you get the temp up to 180-190.
Next time you use the truck, try covering half or so of the radiator with cardboard to get the engine up to a proper operating temp, 180-190, and see what happens.
Just a thought,
BC

 

[neb4x4]

Man, I wish my M35 would get that warm, (180 or so.) I can drive mine for 25 miles and it hardly cracks the gauge!!!

 

[jwaller]

Man, I wish my M35 would get that warm, (180 or so.) I can drive mine for 25 miles and it hardly cracks the gauge!!!

you also have something very wrong and you need to correct it. run it that cold and you will soon have engine problems. use an old pizza box on the rad if you have to.

 

[neb4x4]

Well, I have a military issued winter front cover over the grille.... I drove it home from where I bought it, it was 5 deg outside... It took 50 miles to warm up (about 170 or so). I changed all the coolant hoses etc.... Inspected the "so called thermostat" and new coolant. Saturday I drove it about 15 miles one way, the temp was about 60 deg and it still did not crack the temp gauge... But the heater hoses, and rad hoses are warm. But not HOT. There is no "thermostat" in these rigs. Like I said before its more or less a big copper washer with a hole in it! Nothing to "restrict flow" till the coolant reaches a certain temp. It is in constant loop. Yeah the copper restrictor "thermostat" has spings on it, but nothing to open and close. I have checked into a new one, thinking mine has been altered.... NOPE! same thing. Any advice???

 

[m16ty]

All the sending unit does is complete the ground to the gauge. You either have a short in the wire going from the gauge to the sending unit or a bad sending unit.

 

[BEASTMASTER]

mine grounded out one nite plowing wwhen i saw the gauge it was pegged at the 240 side .jumped out ripped off the winter front, tore open the hood,but saw no steam,and the motor didn't seem like it was cooking,. noticed the old pull stop cable was against the sending unit grounding it out. boy was i sweating bullets. but everything went back to normal and finished the night with no other problems.

 

[wdbtchr]

I'm having the same problem with the coolant temp and the oil temp on my DTC 8606 forklift. Do all the military systems use the same sensors for the 24 volt systems? Does anyone have a part # or a source for replacemtents?

 

[velociT]

The gauge is only as good as the lowest bidder.

As is the LV Monorail.

My former roommate sprung that beauty on our mutual friend with anxiety problems when we were on it, going about 45.