Engine overheating

[Full Throttle]

92 Ranger 4.0 manual 4x4. Trucks does fine around town and on the highways. It wants to get hot soon as I go off road and start heading up in the mountains. Coming off the hills its all down hill no problems. Just seems to get hot try to go up grades at slower speeds. Temp will come up on highway grades but not bad. I flushed to radiator no change. Im thinking its the clutch fan but I would think it would do it in town or at a idle.

 

[FritzTKatt]

It's not coming up at idle because you aren't revving it. See what happens if you high idle it at like 2.5k for a few minutes. How old is the thermostat? Did you flush the system with the heater on? Any indication of a failing water pump?

I like your logic on the fan clutch, it seems like a good start. I don't know how to function check a clutch though.

 

[Full Throttle]

Reason i think fan is because even when hot fan wont increase speed when reved up. Then when i shut it off sits there and free spins.

 

[Andy D]

A bad fan clutch will over heat an engine at idle.

 

[RonD]

Reason i think fan is because even when hot fan wont increase speed when reved up. Then when i shut it off sits there and free spins.

Replace fan clutch, if above is true, fan clutch is at least part of the problem.

Next time engine is up to operating temp, shut it off and move fan shroud out of the way(two bolts at the top), run your hang over and down the rad fins and feel for any cooler spots, lower rad should be cooler than upper rad, but you are feeling for any cooler spots which would be blocked tubes.
These can not be flushed clean.

If fan shroud is missing replace it, the shroud is what allows the fan clutch to work, the clutch is heated by the radiator not the engine, if shroud is missing then cooler air comes in from the sides and clutch doesn't get hot enough to fully engage.

If you do alot of low speed "crawling" a popular choice is switching to an electric fan for the rad, you get a couple of extra horse power by removing belt driven fan, and better low speed cooling.

Vehicle cooling systems are designed with the expectation that during higher engine heat production(higher load) there will also be more rad cooling available via air flow(higher speed), low speed climbing doesn't fall into that design parameter, the e-fan gives it the higher air flow.

 

[Full Throttle]

Put new fan clutch on and went up in the hills. Everything works great now. Mobbed on her pretty good and could only get it up about 1/3 way on the guage. Thanks guys for the responses. Also on e fan i seen local parts house had 12in for $59 its universal and blows 850 cfm. Thinking about getting one of those and mounting it on front of a/c condenser so when im towing i can get a little extra air flow.

 

[FritzTKatt]

Well, that was easy...

Take a look at your radiator and check to see there's not a bunch of crap plugging up the fins. When I worked on the dairy farm I had a problem with hay/dirt/manure getting up in there and had to wash it out. Won't hurt to have a clean radiator...

 

[Full Throttle]

Yeah superclean works great for getting bugs out of fins. I use to have to do that about once a month on my old semi. Got smart new semi has bug screen over radiator.

 

[RonD]

Put new fan clutch on and went up in the hills. Everything works great now. Mobbed on her pretty good and could only get it up about 1/3 way on the guage. Thanks guys for the responses. Also on e fan i seen local parts house had 12in for $59 its universal and blows 850 cfm. Thinking about getting one of those and mounting it on front of a/c condenser so when im towing i can get a little extra air flow.

Good work

Extra air flow doesn't hurt, make sure it is blowing the right way, lol.

You can get temp sensors that slide into the fins in the rad that have adjustable ranges, these activate the e-fan relay