I have a new to me 94 powerstroke and plan to put a lot of miles on this one in the future. I've only had it about 3 weeks now but pretty much have all the bubba jobs fixed and the truck running like a champ. It came with a nearly new slide in camper and I just love it.


Anyway, I replaced the thermostat a few days ago. I thought I was being slick and sandblasted the old housing, repainted it and reused it. It looked like new. It started leaking yesterday though. I should have known better than try. I used a stant thermostat, short stem one like is supposed to be in there and now that I've been researching thermostat housings I'm worried about it. It's amazing that in all the years I was a Ford mechanic I never knew there was a difference in thermostats in these things.

I was wondering if my pump takes the short thermostat but these things supposedly aren't safe for the back two cylinders then what is the fix for it? can the pump and tstat from a 97 truck be used instead?

This truck ran cold with the stuck open thermostat that was in it when I got it but with a new one it's not that warm really either unless I'm really loaded. Normally, 190 is about what the upper hose is running at when I've come in off a trip to town. I checked with a laser thermometer.

This year sometime we'll be loading up the camper and a couple horses and heading for Alaska way up North on the coast of the Bering sea all the way from Texas. I want to fix any potential problems before they become a problem. Last time I did that trip we covered at least 2000 miles of dirt roads and I some pretty serious mountains. Not many parts houses on the way either. That trip was in a 4 banger Ford ranger. I'm going in comfort this time.

 

From what I have heard and read the thing to do is install the 203* thermostat. I believe there is a sponsor on here that has them. Whenever I pull a thermostat housing I always clean the gasket area with 120 grit sandpaper laying on a flat surface

 

If its an early (94.5 to 95) pump then it should already take the 203 stat from just about any aftermarket supplier. The late 96 and up pumps take the 195 stat or the 203 that is only availible from Diesel Site.com. Nothing wrong at all with running the 203 stat. The change to the colder stat was for emissions not effeciency. It won't hurt the motor one bit.

To answer the question about WP interchange though. yes the later pump can be put on in place of the early pump but the stat must be changed with it as well as the pipe for the heater hose. The early pump uses pipe thread and the late pump uses straight threads with an 0-ring seal.

To seal your leak remove the stat housing. bend the three ears down just slightly and put a smear (thin!) of silicone on there.

 

X2 with TJ
Also if the lower hose inlet is a bolt on type it requires
the long stat.

Bill

 

The stant thermostat I put in was a 203 but I seriously doubt it will ever reach that unless I'm really pulling. I'll find out today. I'll be pulling a 40 foot gooseneck flatbed full of hay. That will give it a workout.

I'll hook up my scope in the cab with a temp probe taped to the upper hose and see what it get's.

I just went out and looked at both my powerstrokes ( a 94 and a 97) and the WP differences are exactly as you describe. I never knew that before. It won't be hard changing the old one over at all. I need to replace the fan clutch on it real bad so no better time to do it then at that time. Both engines need new thermostat housings. They are siliconed in place but still leak a bit. I gave both of them overnight to dry before filling the systems back up too.

 

I'm not sure you can even get the older style water pumps anymore. If you have the newer pump (long thermostat) then the short, Stant 203º, might damage your engine.
From Diesel site advertising the long 203 stat:

 

I guess what he is saying is that the short stem tstat can damage the engine if used with the newer water pump but not if it is used in the old water pump that it was designed for.

The way that is written it sounds to me like the short stem is bad in either pump. He should reword that a bit if it's not the case I think. That article is what got me worried.

 

I bought a new, old style water pump from advance auto parts. I never knew there were two styles until I got on this site or I would have told them a96 pump instead.

 

Both pumps are still available!

The problem is caused my the short stem stat in the long stem pump. No issue running the correct short stat in a short stat pump

No need to change to the later pump. IMO the early pump is more desirable. I resist one off parts that aren't readily available when traveling. With the early pump you can buy a 203 stat at most any parts stores. With the late pump you can only buy a 203 stat from Diesel Site.com. I don't like that so last time I changed my pump I put on the early pump and ditched the late pump.

 

X2

Problem is both long and short are stant.
They are both a POS.
Lucky to get a year out of them before they get out of range!

Bill

 

Even at a year for $10 I can still change it every year from the corner parts store and still be ahead from Bob's stat that he says should be replaced every year........

Bill does any one else make a shorty other than stant?

 

Agree!
Behr-Thomson, its a german stat. (IH Oem)
Problem is the cost is the same and more than Bobs.

My next move is to an electronic stat setup.
Just not much to work with as of now.
Bill