overheating rpm dependent

[firehawk]

Long, fun weekend of racing, but my truck now has a new problem: overheating. It seems to be rpm dependent, as even as a fairly low speed, it will run hotter with a lower gear. Also, a/c on or off makes little difference, and pulling or not a load makes little difference. Coasting down a hill in neutral cooled it off a good bit, but running level at 60 or higher would see very high temps.

I was too tired to take temp readings of various parts plus it cools down fairly quickly at idle.

For reference, the truck did not loose coolant and I have a new radiator of oem design and the engine is all stock. Stat and water pump were replaced about 4 years ago, but not by me, and I don't know what they used, but I am fairly certain the stat was not right as it takes too long to warm up.

My first guess is either stat, collapsing hose, or water pump, but I would love to hear some suggestions.

 

[justinray]

Bad water pump or low coolant would be my swag.

 

[icanfixall]

I say fan clutch because when your traveling fast the radiater sees more air to cool the water. Use an inspection mirror to look at the thermostatic spring on the radiater side of the fan clutch. If its got dirt bilt up on it or its wet around the seal its shot and you need a new one. So the truck has a new radiater. How many fins per inch and how many rows of tubes is it. As far as the thermostat goes. Replace it no matter what. You want only the ford or international factory thermostat and it opens at 192 degrees. Nothing else works well enough to keep these engine running cool. The aftermarket stats can't pass enough coolant to keep them cool.

 

[justinray]

I was leaning away from fan problems, because he said even going 60 mph it would overheat, at that speed, you shouldn't even need a fan, if all else is working well.

 

[mblaney]

Fan clutch. that was the last thing I replaced on mine and it fixed the problem

Not all bad, my rad lasted 19 years and started leaking so had too be replaced anyway.

 

[riotwarrior]

K I'm going with Tstat here guys, at 60 mph and flat he's over heating....fan is not an issue at that speed really.

Can you grab the lower hose and crush it easy with your hand? If so then replace it with a good GATES or something similar!

As for Tstat, get a FoMoCo or IH only no other one is acceptable, now will it flow enough.

Also changing tstat is the LEAST expensive route and then you know, it's good for like 35 bucks and a couple hours work!

How can you go wrong?

JM2CW

Al

 

[firehawk]

The radiator had the same fin per inch and cores as the original. I spent some time finding one like that.

The fan clutch did feel like it had plenty of resistance when I checked it, but it was not locked up.

I am going to buy a ford stat, but what should I get for the water pump if I replace it too?

 

[riotwarrior]

I am going to buy a ford stat, but what should I get for the water pump if I replace it too?

FoMoCo

Nuff said

None of that cheapnese or cheapexico reman crap with a foreverneverworkright warranty, pay once and pay for quality!

JM2CW

Al

Oh and if you look, if you are not familiar with replacing them on these trucks, do advanced search and use key words like water pump or thermostat along with my username and you will find two well documented replacement threads I wrote with lots of pictures!

 

[firehawk]

Installed new ford thermostat. Cooling is now fine. It warms up much quicker, like it should, at stays in the middle of the gauge. The old stat looks really old and had the rubber sheath come apart and part of it was keeping the stat partially open, and likely would not let it fully open.

You must be registered for see images attach

You must be registered for see images attach