1990 F350 7.3 n/a overheating

[pcpotter1023]

Zaroot, I want to thak you for your post I've been having the same problem lately as long as I'm not towing temp is great but when I put a trailer behind mine (it doesn't have to be a heavy one either) and start getting to speeds around 65 or higher it starts getting warm I changed the thermostat and that did help some but Old Red will still run warmer than I like (about midrange or a little higher) after reading through all the replies I believe I'm going to change the fan clutch I just put a new Gates water pump on it old on went to leaking, I do have one concerne though when I changed the thermostat most of the rubber seal that was surrounding the thermostat was gone.
Again thanks for your post

 

[IDIBRONCO]

There's no rubber seal around our thermostats. The ones with that seal are for a 7.3PSD. Will they work in our engines? I have no idea.

 

[zaroot]

Zaroot, I want to thak you for your post I've been having the same problem lately as long as I'm not towing temp is great but when I put a trailer behind mine (it doesn't have to be a heavy one either) and start getting to speeds around 65 or higher it starts getting warm I changed the thermostat and that did help some but Old Red will still run warmer than I like (about midrange or a little higher) after reading through all the replies I believe I'm going to change the fan clutch I just put a new Gates water pump on it old on went to leaking, I do have one concerne though when I changed the thermostat most of the rubber seal that was surrounding the thermostat was gone.
Again thanks for your post

You are most certainly welcome! There is a great deal of knowledgeable wizardry on this page, and if you can put in the time to read and try methods already covered, you can fix/assess your problem 99% of the time. I was swayed to fix my junk and keep it on the road, going to be about 25% of the cost of the 5.9 swap I really wanted, but hell $3k buys a lot of fuel!

 

[zaroot]

There's no rubber seal around our thermostats. The ones with that seal are for a 7.3PSD. Will they work in our engines? I have no idea.

Correct, not like a typical gates or stant that has that little o ring or butyl seal.

 

[zaroot]

Making some progress! #7 is was. Had some coolant and rust in there. Passenger side head was pretty clean. Block is pretty true, machinists straight edge isn’t picking up any variances. Probably have the heads hot tanks and magnifluxed. Check guides, and throw in new valve seals.

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[IDIBRONCO]

Man! That's one tough milk crate! It must be made of steel or something like it to support an engine. Since your heads are off, now would be a good time to do the 7.3 cooling mod.

 

[zaroot]

I would but I already have 2 sets of 7.3 HGs. One came with a donor truck and the other I purchased prior to understanding the cooling mod. At 7psi of boost and the heaviest load being 7-8k lbs, I think it should be alright.


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[IDIBRONCO]

Most likely.

 

[zaroot]

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[zaroot]

Getting close!

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[Jason1377]

Looking nice even the fire lol don't burn any thing

 

[Alwaysreadyrob]

MY 1994 7.3 TURBO STOCK DIESEL F 250 IS ALSO GETTING HOT AND WE JUST CHANGED THE THERMOSTAT....WE DID NOT CHECK IT AND,
IT MAY BE THE WRONG ONE.
CAN ANYONE TELL ME THE PART NUMBER FOR THE CORRECT TEMP ON MY THERMOSTAT ? I USUALLY GO TO OAKHURST NAPA BECAUSE I LIVE IN THE MOUNTAINS AND IT IS AN HOUR DRIVE DOWN TO FRESNO ( yuk fresno! )

 

[IDIBRONCO]

MY 1994 7.3 TURBO STOCK DIESEL F 250 IS ALSO GETTING HOT AND WE JUST CHANGED THE THERMOSTAT....WE DID NOT CHECK IT AND,
IT MAY BE THE WRONG ONE.
CAN ANYONE TELL ME THE PART NUMBER FOR THE CORRECT TEMP ON MY THERMOSTAT ? I USUALLY GO TO OAKHURST NAPA BECAUSE I LIVE IN THE MOUNTAINS AND IT IS AN HOUR DRIVE DOWN TO FRESNO ( yuk fresno! )

Your thermostat may be stuck closed. The only ones to use are the Motorcraft ones. All of the others can (will) give you trouble.

 

[snicklas]

Or if you have a Navistar Truck dealer closer you can get:

1807974C94 Thermostat

That is the part number for the (6.9/7.3 IDI - Ford) (421/444 - IH/Navistar/International) thermostat. I have bought one from my local International Parts Counter. They had it on the shelf.