1994 Ford F250 XLT 351W E4OD Regular Cab LWB 2WD

I bought this truck yesterday, and I discovered this little problem on my way home.

While driving down the highway, the 'ol truck sits around the "o" in "normal" on the temp gauge. Sometimes it'll go to the middle of the gauge, but most of the time, it sits around the "o".

When I pull into a parking lot, stop at a redlight, or slow down to 5-10mph, the needle goes up to around the "m" or "a" on the gauge.

I'm suspecting a sticking thermostat, but I'm not exactly sure...

I went by Auto Zone and a buddy of mine that works there is betting on the fan clutch, but when the engine is warm and I try spinning the fan by hand with the engine off, it's still tight to spin, and I've never even heard a fan clutch on one of these older trucks "kick in", even after I installed a brand new one on a 1992 F150 with a 351.

I have a new thermostat that I will be putting in tomorrow. It's the OE 192*, if I'm not mistaken. I just made sure I told them to give me whatever came out in the truck.

By the way, when the truck has warmed up, the upper radiator hose is nice and tight, and I've not noticed any leaks anywhere. The coolant reservoir was empty but the radiator was full when I bought the truck. I went ahead and added a 50/50 antifreeze mix to the "full" mark on the reservoir.

Is there anything else that I should be checking, though?

Thanks for any insight!

Nightrain

 

Update:

I still haven't got the new thermostat installed yet, but I'm hoping that my problem is solved...

Here in the past day or so, the truck hasn't gotten about the "o" in "normal" on the gauge.

Is it possible that the thermostat was sticking from the truck sitting so long on the lot, and it stopped sticking all of a sudden?

I'm still going to put the new one in, just in case... I'm just trying to figure out exactly what's going on.

Thanks for any insight!

Nightrain

 

it could be the thermostat sticking, and it could be the radiator, if the truck has quite a few miles on it it may be time for a good flush job what does the neck of the radiator look like when you take the cap off and look down in it. or maybe a combination of the two. on the clutch fan with the truck running and up to temp you should hear the fan engage as soon as id does shut the truck off and try to spin he fan it shoul be pretty difficult to spin. and as long as the antifreeze mixture is correct. hope it helps

 

The truck has 164k on it.

The neck of the radiator looks good.

I was thinking of having it flushed, but I wanted to use that as a last resort, just to see if anything went to leaking.

The fan is difficult to spin with the engine off. I'm beginning to lean away from it being the clutch...

Thanks for your reply!

Nightrain

 

Engine warm or cool?

If the engine is cold (as in like how it is here right now, 26*), it will be difficult to spin. If the engine is warm (as in fully warmed up) it should be hard to spin. If the engine is anywhere in between, having run for maybe 30 seconds to warm up and get the fluid in the clutch moving, it should spin easily.

Just my two cents, been there, done that, fought that.

 

I had driven the truck about 5 miles and it had done the overheating thing described in my 1st post twice. I cut the truck off at the parts store, popped the hood, and manually spun the fan. It was hard to spin.

The temps here have been in the 40's and that's another reason I was pointing to a faulty thermostat.

Nightrain

 

Oh okay, five miles and overheating, the clutch is definitly warmed up. I agree with you then, sounds like a stat issue.

 

What's thrown me off, though... Is that it has seemed to stop. The truck now seems to be acting like any other mid-90's Ford that I've had... It sits around the "o" in "normal" (about 1/4 way).

Maybe the thermostat has started working correctly, but I believe I'm going to go ahead and change it out tomorrow. The last thing I want is for it to change it's mind and fail on me somewhere out on the road. I might even go ahead and flush the system, as long as nothing looks as if it's leaking...

Thanks again for your response!

Nightrain

 

Okay, here's my update:

Saturday, I installed either a 192* or 195* thermostat and put it all back together. The truck did fine until yesterday. It started going up toward the "r" and "m" in "normal" on the gauge. It hasn't gotten higher than the "m" yet, but it's still getting a bit too warm.

Now, today when I got out of the truck from driving home from work, I smelt coolant. I popped the hood and noticed that my thermostat housing is leaking from my crappy gasket/sealant job. (BTW, I ABSOLUTELY HATE messing with gaskets. Anytime I do anything, I always get a leak... No matter what. Anyway...).

But, I also noticed the crimps around the radiator, where the aluminum core meets the plastic sides, is getting a little wet. So, that reminded me...

My '94 F150 with a 302 did the same thing in the cold of winter a few years ago. It was the same thing. I installed a new radiator and didn't have any other problems. So, I'm thinking that's what this F250 needs... A new radiator and for me to re-do the thermostat housing gasket.

Is there any tips that ya'll can offer me with gaskets and keeping them from leaking? I used thermostat housing/water pump gasket maker and a Fel-Pro gasket. I installed the thermostat first, cone side facing the radiator, put sealant on the both sides of the gasket, mated it with the housing, and put it all back together. Now, granted... My problem may be that it was in the 30's that day, and I started the truck and drove off in it immediately after I was finished. Maybe I should have let it sit for a little while??

Also, can ya'll offer any other suggestions on getting the old gasket goop off of the housing and the intake surface? This is one of the other biggest problems I have with one of these jobs. I always try to clean it best I can, but I always feel that I don't do good enough...

Thanks for any insight.

Nightrain

 

personally i never like to use silicone goop it makes a mess. if you get both surfaces good and clean take you new gasket and give it a coat of spray paint silver works good has metal flakes i it or copper kote has a gaske spray works good and install. something i didn't think of before have you tried using anothe means of checking the temp i had an old 81 ford that had a temp sending unit go bad and would give freaky readings. like a laser temp gun to see maybe the thing insnt oveheating at all.

 

Thanks for your response.

In my past experiences, I will NEVER use that copper-coat crap again. I used it as a reccomendation on a 351W timing cover gasket, and I had to redo the job all over again because it leaked. I cleaned on that thing forever and ever, and even cleaned the block surface as best I could... I still got leaks.

I've never really had a problem with the goop, I just get nervous about crap like this. I don't really know why... I think the biggest problem was I should've let it sit up for at least a few hours since it was so cold.

Do you have any good suggestions for cleaning up the parts that are going to get sealant and gaskets?

Oh, almost forgot... I'm not sure if the temp sensor is correct or not, but I do know that the radiator is leaking and will have to be replaced. That was the problem on my '94 302, and hopefully it will correct the problem on this F250.

I'm hoping this overheating/leaking thing was the only reason (if it was even the reason at all) this truck was traded in... Simple fixes like this are not a big deal. I'm just hoping there's nothing more.

Thanks again!

Nightrain

 

for cleaning the old gasket surfaces i usually use a razor blade you can lay it almost flat and get under the gasket and it will usually come up rather easily. once the gasket is off both surfaces, if its not a clean as you like take a little sandpaper and give the surface a little scuff. then a little brake clean to wash and let it dry and its clean. I used to use this stuff called gasket eliminator napa makes it as well as permatex i believe. looks and has the cosistancy of grape jelly. and its an anerobic sealant which means it wont harden till air is taken away. its good stuff. im not crazy aout silicone cause ive worked on stuff people have used so much on it has actually damaged the engine, it squeezes out inside the engine and look like litle worms then gets sucked into water or oil passages. plus the other stuff wont harden up untill after you put the part together.plus when you take the thermostat housing off and have the surface cleaned up take a flat file and give the surface a few light strokes to make sure the surface is god a flat ive seen some where the bolts are so tight the ears will be a little warped. Hope it helps I would definatley check the temp with some other means after you replace the radiator to rule out a bad sending unit.

 

I "think" that anerobic sealer is called Hylomar. It's good stuff but the surfaces need to be perfectly clean and dry. I haven't used it in many years.

 

Thanks for your response with all of the great suggestions for cleaning gasket surfaces!

I borrowed a cooling system pressure tester from Auto Zone today, and it shows the system to be in perfect working order. It held 13lbs. of pressure for over 5 minutes, and when I started the truck, the needle didn't jump or move a bit. According to that gauge, everything is in good working order.

I looked the radiator over a little better, and I have noticed a few more wet spots, but nothing serious enough to replace it yet, IMO. I'm going to get a laser temperature tester this weekend and check it with that.

It seems that the thermostat housing has stopped leaking, for now anyway. I'm going to save that until it starts leaking again, also.

I just thought of pressure testing the system today, and I'm glad I did. It saved me $150 for a little while.

Thanks again for all of the suggestions. I'll be in touch and let ya'll know what happens over the next few days. Probably around tax time, I'll go ahead and install a new radiator, along with a good system flush. I hope that will take care of everything.

Thanks again!

Nightrain

 

You never did tell us if the water level in the overflow tank ever changed... Maybe the water was just low enough to allow the motor to overheat some...

My 351W is always in the center of NORMAL on the gauge. The only time it climbs is when using A/C in the heat of summer. Bought a nice new 3-core row radiator, too.