Overheating

[ISPKI]

Hey folks. So ive been driving my freshly zf5 swapped 94 f250 7.3 for a couple weeks now. I was picking up 2x4s yesterday afterwork with a friend of mine, left the truck idling while we loaded up boards, took about 10-15mins. When we hopped in to leave, i noticed steam coming out the driver side, overflow tank was boiling over. Boiled out maybe 2 bottles of coolant. Let the truck cool for an hr but wouldnt start after that and had to have it towed.

This is my first foray into cooling systems. It seemed that the fan was pretty easy to spin even immediately after it overheated. It also seemed to get harder to spin as it cooled.

 

[franklin2]

These engines never seem to have a heating problem sitting there idling. They only build heat under load going down the road.

Do you have a real temperature gauge on the truck? Not the factory gauge. That would be a good way to monitor what is going on. May be thermostat problem. No white smoke out of the exhaust correct?

 

[hesutton]

What does your coolant temp run normally? Has it been getting hot before this happened?

I agree with the above post, these rigs warm up when they are worked hard. Not seen my IDI's ever get warm at idle. Not heard of it before either.

When you said it wouldn't start, was it turning over or was it locked up? How old is the water pump? Thermostat factory part or aftermarket? Have the factory radiator shroud on there?

Just trying to get some idea why your rig would boil over at an idle.

Heath

 

[DaveBen]

Is it running right? Missing? You may have a blown head gasket.

 

[ISPKI]

It was running great before. I havent had time to start it since I towed it home. No white smoke out of the pipe. It turned over just fine when i had tried to start it but it wasnt pumping any diesel out of the tailpipe so im assuming the pump was too hot to pressurize the fuel at the time.

The factory fan shroud is on it and I did the water pump last year but i didnt change the fan clutch.

 

[ISPKI]

I lost power to most of my gauges after i installed the zf5 a few weeks ago. I had an electrical isdue where the red/green stripe power wire feeding to the ignition switch was grounding somewhere in the cab up in the dash. I cut it at the firewall and routed a new wire to the switch so i could start the truck but now i only have speedometer, none of my other gauges work so no idea on temp.

Coolant temps begore i lost my gauges have always been on the low end.

 

[catbird7]

Mine overheated while just idling before replacing the fan clutch. Fan was not loose nor made any noise however when I replaced the clutch, it was a night & day difference!

 

[ISPKI]

Yeah i think im going to start with the thermostat since I wouldnt be surprised if its the original and I will weld the fan clutch in place and see if it solves the issue before I spring for a new one.

 

[IDIBRONCO]

Your fan clutch isn't working right if it spins easy when hot and then harder when cooled down. Between that and the thermostat, I think you're on the right track.

 

[Hydro-idi]

Your fan clutch isn't working right if it spins easy when hot and then harder when cooled down. Between that and the thermostat, I think you're on the right track.

Actually if your fan clutch is doing what's described here, it's probably working properly. It's when the fan clutch spins easy when cold is when you know you have a problem. Also inspect the bearing seal on fan clutch. If it's wore, you'll see an oily mess which means it leaked out its internal clutch oil and is toast.
I still agree that it would be a good idea to replace both the clutch and thermostat.

 

[icanfixall]

To determine if a clutch is shot look for dirt and grease on both or either side at the shaft. Its shot if any wetness is seen.I have seen the spring side completely covered in dirt from the shaft seal failing. That viscus fluid leaks out and dirt is attracted to it.

 

[jayro88]

I highly doubt that a bad fan clutch would cause overheating at idle. I say this because my IDI won't even get close to the temp where the fan clutch kicks in at idle. My bet is on a bad thermostat that won't open or a water pump that is not pumping.

My suggestion would be to replace the thermostat and then do a good coolant flush. I just use the Prestone flush. Put in 2 bottles and drive it for a day. Then drain everything and refill with the correct anti-freeze of your choice. Just doing this caused my temps to drop 10*.

I am not saying that you shouldn't change the fan clutch, I am just saying I don't think it would be causing your overheating issue. Also, not sure if welding it is a good idea.......wouldn't that put an awful lot of stress on the water pump shaft?

 

[ISPKI]

Actually if your fan clutch is doing what's described here, it's probably working properly. It's when the fan clutch spins easy when cold is when you know you have a problem. Also inspect the bearing seal on fan clutch. If it's wore, you'll see an oily mess which means it leaked out its internal clutch oil and is toast.
I still agree that it would be a good idea to replace both the clutch and thermostat.

That isnt how I thought fan clutches worked. shouldnt it tighten up as it gets hotter so that it spins faster to cool the engine more. If it loosened up as it got hotter then wouldnt it spin slower and cool the engine less?

Hopefully I can catch and reuse my coolant. I just flushed and changed it out to CAT ECL last year after installing a new oil cooler assembly.

 

[Hydro-idi]

The clutch oil will thin out when engine warms up, making fan clutch spin over by hand easier when engine is off. Once engine hits a certain temp when running, the clutch will lock up engaging the fan to pull air.
Probably didn't explain it very well in previous post. Sorry for confusion

 

[ISPKI]

I checked the Thermostat and it seems to be working perfectly fine. Boiled a pot of water and it opened up smooth and easy. The water pump seems to be pushing coolant just fine and isnt leaking at all and the fan clutch is not leaking any oil and spins freely when cold. I am looking at my A/C condenser as being a possible culprit. It looks like its been hit by a whole bunch of baseballs over the years, lots of flattened out fins blocking the main radiator. I have never had AC in this truck and the lines are already broken so im just going to remove it and see if it helps with cooling.