Neighbor's mule is overheating. Engine runs fine. He says the cooling fan won't come on and it overheats pretty quick and blows coolant out the overflow/over pressure. I told him I'd have a look at it. Got to be: thermostat, fan, or radiator. Or a blockage.

You Mule owners, where would you look first? Whaddayathink?

I don't have a Mule just a Polaris but a quick check of the Interwebs suggests this..


"If your fan is not coming on, chances are that someone did not get the air out of the cooling system. There is a switch in the radiator that controls the fan, if no coolant is in contact with the sensor then your fan wont come on and the engine gets hot. To solve this you have to run the Mule until it gets warm and then park it on a hill with the nose up in the air. Let it cool completely down then check your coolant level on level ground. 9 out of ten times that will solve the problem. Otherwise it is a stuck thermostat. However if it is diesel Mule....."

Gas mule. New thermostat.

By golly, that might be the answer. My neighbor had it worked on by a shade tree mechanic. The STM replaced the fan, fan switch, and thermostat (says he did), and the problem wasn't solved. My neighbor is gonna think I'm a genius, and naturally I'll take full credit for the fix. :-)

There you go

Think if he purges that air and gets the burp out, he is good to go and retop off the coolant level..
Good Luck Sir

The fan is run by a thermostat that mounts on the backside of radiator, that is the problem. Your can test that by removing the two wires and hooking them to a test light with the ignition switch on the light should come one but you also the to check for vapor lock in the radiator lines. Been there and one that.
Sniper is also correct and if you look at the metal lines leading from the radiator there are bleed plugs and there is a bleed plug on top of the of the engin where the fuel lines come in. Place the mule on and incline with the radiator cap above the fuel line coming to the engine. remove the plug and fill radiator.

Ok...ran it up on a slope, took the radiator cap off, filled the overflow bottle, cranked the engine. Then, as the engine warmed, air bubbled out for a very long time. We kept topping off the radiator. Finally ran out of bubbles, capped the radiator, and the fan came on. We drove around a while and no overheating. Looks like the problem is fixed. Thanks very much to Sniper and Tigger.

The guy that worked on the Mule for my neighbor replaced the fan switch, head gasket, thermostat, and maybe even the fan itself and didn't fix the problem. He didn't know to burp out the air. I don't think I'll tell my neighbor, but I really don't think the Mule really even needed to be worked on, other than burping it. He's out $1800. I think it best that I not tell him. He might stroke out.

Again, thanks much for the suggestions. They were good suggestions. Show up at my place and the beer is on me. Latest beer purchase is Pacifica.

Outstanding

I'd tell your neighbor in hopes he never uses that mechanic again... but that's me

glad you got it figured out

Well dang it, the neighbor just called. It overheated again, sort of, but this time the fan ran. Said the overheat light came on, but it didn't smell hot or seem overheated. Maybe I didn't get all the air. Supposedly there are some bleeders near the thermostat. I'll pull it back on the ramp, fill the radiator, open the bleeders and let any air escape. Then run it again to see if I could get more air out.

If I got all the air the first time, and air keeps showing up, it's got to be the head gasket. But, the neighbor says the shade tree guy put a new head gasket in it.

Could it be the temp sensor in or on the radiator?

Repeat the process then if continuies replace that T stat sir and look for Voids or holidays in that new head gasket...

REALLY hope he didn't get any debris down in there...
At this point...

I would roll back up and say..

We will meet you half way...I will supply parts, You Labor and I watch...shake hands and you hAVE EVERYTHING NEW . So Sorry and hope it gets resolved before season..


MY 10 cents, chingly in that gasket and getting air and creating Burb...

Where is the danged thermostat? Must be on the engine.

You can not get all the air out unless use the bleeder valve on an incline just had same problem with Polaris ranger. I also had to squeeze the hoses to help burp the air out, but not sure if that is necessary on a mule.

That's worthwhile info, cattle69. The guy and I are going to have another go at getting the air out tomorrow afternoon. I'll trace the water lines and find the bleeder valves (that's the plan anyway).

are you sure the water pump impeller is circulating water? Thermostat put in backwards?

If he replaced fan make sure fan is pulling air through radiator and not blowing air out. If it is blowing air outwards will need to reverse polarity (switch the wires).

The bleeder valve is actually a bolt on the thermastat that can loosen to bleed the air not an actual valve.

Yes, I know. We bled that rascal down yesterday and, to the best of my knowledge, we got the air out. Then the guy followed me home (3/4 mile) and all was well. The fan ran for a long time. Is that normal for a Mule?So we visited for a while, and the fan shut off. Then he fired it up and they went home, and 200 yards from my house the 'hot' light came on. He said he drove it on home and it showed no actual sign of really being overheated. Didn't spit any coolant.

He asked "what do we do now"? I suggested that he just trade in the old warrior and get a new one. That old mule is worn about out. And I'm tired of working on it.

Fan runs for a couple minutes before it shuts down. the fan switch is on the radiator so the water in the radiator has to cool to the point for the fan to cut off.

Keep this post going. I got an old mule and have learned so much that will help me keep it going and going.

If my neighbor buys a new Mule, then this chat will fade out. When I suggested that he might be happy with a new one, he agreed and said "red would be a nice color this time". But...he might want to just stay with the old one. He can be frugal at times.

He had the Mule works on by an outfit that I recommended to him, and they fixed nothing. What I didn't know was that the guy that did the good work for that shop had died. Soooooo, I felt a little responsible and sought you guys out for info - and got good info. And then I volunteered to help work on it. I'm retired and mechanically inclined, and I like a challenge. So, if he keeps this Mule, I'm going to take tigger's advice and clean the externals of the radiator. That's one thing we haven't done yet, because the dang radiator is hard to get to. Also, I'll check to see if the radiator has re-acquired air. If so, I'm thinking it has a bad head gasket. If so, it's time to take it to Kawasaki for repair or replacement.

Keep the radiator clean.. need to put high pressure air from the inside out with a wand...

What happened? Did you get it fixed?

Just bought a 3010 trans mule that was overheating, just my luck after just fixing a ranger doing same thing. This mule would over heat when only going slow after about 30 minutes. The fan would never come on. First I bleed the air out of radiator and got it hot and set on incline. This didn't make fan work. Next there is a breaker under seat that needed to be checked it is the one with two blue wires running into it will have a green tab stuck out if tripped. Well the breaker was good. The third thing I checked was the wires and that was where I found the problem. Rats had chewed the wires running to the breaker under seat. The bad spot was right wher all the wires were tied together. Hope this might help someone else.

Update on the overheating Mule. We didn't fix the problem. I suggested that he get a new or newer Mule and he thought that was a good idea. Whether or not he did, I haven't heard. Unless he has a problem with something, I don't usually hear from him. I'm sure you guys have friends and neighbors like that.

I did see his wife the other day. She came over on that Yamaha Big Bear I sold them. It was, as always, purring like a kitten. I asked if her husband had gotten a new Mule and she said that he hadn't and didn't even know what he was planning to do. She said that she had the Yamaha, life was good for her, and she wasn't worried about the husband. She smiled and left in a cloud of dust.

I wish he would buy a new one. I'd like to see one. His old one, the one we couldn't fix, is a ragged out, wore out, sad pile of machinery. I'd call him to see what's up, but he might need me to help him fix something. Let sleeping dogs lie.