Hello again. It's been a year. Last summer I posted details about our expedition overheating while towing our camper. We have used this vehicle to tow the same trailer for 8 years. With help from the forum I thought I had it solved. We attempted to tow our camper again this past week and after 10 miles down the freeway it overheated again. It stays steady just below half way, but then once it rises above half way there is no stopping it. Here are the repairs we have done.

Before it started overheating we had the head gaskets replaced because of an oil leak. 6 months later we towed the camper for the first time and that's when it first overheated.

After it overheated

Replaced thermostat, radiator, upper and lower radiator hoses, serpentine belt and flushed the system about 7 times.

I checked the fan clutch at cold temps. It rotates a quarter turn when spun. I checked the water pump and listened for the bearings and play in the pulley. It all seems good.

Any suggestions would be appreciated.

Thank you

 

The impeller can break free from the shaft inside the water pump and cause overheating with no outward signs of damage. There's a topic floating around somewhere here with a picture, I'll see if I can find it for you.

 

Here is the post with the picture of the impeller broken loose from the shaft.
https://www.ford-trucks.com/forums/1...l#post14779608

 

Thanks for the suggestion. I've decided that I'll go ahead and replace both the water pump and fan clutch just so the are eliminated from the list of possible sources. I'll let you know what I find.

 

The fan clutch usually shows up as heating up at idle, but I know that when we are towing (granted with an old Buick Roadmaster, but it also has a fan clutch) I can hear the fan roaring away. It's a cheap and easy replacement so worth it.

 

Just a status update:

I replaced both the water pump and fan clutch. The originals both appeared to be in working order. The Water pump impeller was attached and the bearings seemed to be good. The fan clutch motion was a little loose compared to the new one, but not free spinning. I topped off the antifreeze and got out as much air as possible. Initially when I fired up the vehicle the fan was operating at a very high speed, but then eventually went down. I drove the vehicle with no load and the temp held just below 1/2. This is a little less than normal. So I don't have any evidence that these changes made any difference. I plan to try hauling the trailer tonight.

 

If the old fan clutch didn't spin fast initially then it was bad. It will still spin just not just enough to move enough air. Hopefully that solves your problem.

 

I wish you were right but unfortunately the fan is only a factor below 35 MPH. Above that and the forward motion of the vehicle forces enough air through the radiator to make the fan irrelevant.

 

Thanks alloro,

That's what I was thinking as well. I never got a chance to take it for a test run last night while towing the trailer. It will be a couple days before I get a chance. I will post my findings to make sure the thread is closed out.

 

Just to be thorough, you did replace the radiator with one of equal width, height, and depth, correct?

 

The original radiator was 1.75" thick and the one that I installed was 2.5". Otherwise the other dimensions were the same.

 

Maybe the A/C condenser is plugged with "stuff", preventing air flow from getting to the radiator??

 

Thanks for the suggestion. I'll check that tonight.

 

Status update:

So this is an example of the poster trying to be selective about the information that they share. In addition to the issues related to the overheating, I had been experiencing poor performance with the rear heat. It would initially get warm and then quickly blow room temp air. I had been reverse flushing the heater core thinking it was clogged. I had also just recently noticed that after running the vehicle for a while (without a load) the hoses were hot, but easy to compress. So this information might have been helpful for the forum. :-) I had considered replacing the reservoir cap early on, but had always assumed that because under no load the temp was fine and under a load when it would overheat, the cap would release and allow the antifreeze to escape that it was functioning correctly. I bought a new cap for $6 and ran the vehicle for 20+ miles on the highway. The heat works and the hoses have consistent temp and pressure. I suspect that without a load the engine was remaining cool by the limited coolant flow and air. When pulling the trailer it wasn't enough to keep the engine cool. So after a lot of time and money it appears the fix was a $6 part. I haven't pulled the trailer with it yet, but I'll try that soon and report the results.

 

What happened to the rest of the sentence, did you pass out from excitement?