Hi all, I have just been given a 1989 F-150 302 from my grandfather. It needs some work and I've been doing things here and there but have since ran across a small problem in the cooling system that my DIY book from the auto part store is not doing so well on. So here is the problem.
The truck was overheating so I put a new thermostat in and flushed out the system. This fixed the overheating problem, now the needle never gets past the O in NORMAL. However, I'm loosing coolant somewhere? Once I put everything back together I toped off the radiator with a 50/50 mix and filled the reservior hafl way. I ran it for about 50 miles and noticed the reservior was empty and the radiator was a quarted low. I thought this might just be from draining the syatem so I toped it off again and it went right back down. Hoping it wasnt the seals I checked the oil but it was fine I checked the transmission fluid and it was fine, when I park it nothing leaks from under it there are no puddles. So all I can figure is that it is leaking while under pressure while driving but if I drive it for a while pull over leave it running and look under the hood I dont see anything yet the fluid level is always dropping. Any ideas? Sorry this was so long but it was my first post and I needed to tell the whole story on what all Ive already done. Thanks.

 

I would say keep looking, the water has to be going somewhere. Especially check near/under the water pump, My water pump went out right after flushing out my system. It started leaking out of one of the holes near the shaft. It was annoying because I was just trying to help things out but then it just made things worse. Anyway, good luck.

 

WELCOME TO FTE!!!

I absolutely HATE older ford trucks and antifreeze. For some unknown reason I cant ever get them to hold it. I think i finally got it on my 88 though. If you crawl under your truck with a flashlight and look under the water pump, right behind the pully there should be a weep hole. Look and see if you can see alot of buildup of stuff, or wet spots. If its just hardly dripping the airflow from the fan will sometimes cause it to evaporate before it ever hits the ground. Its also possible that fluid only comes out of this when its running.

For your truck its completely normal for the temp to stay there. Thats where it is on my 85 F150, my 88 F150, and my old 94 ranger. hardly ever (unless its summer with full a/c) goes above the o on normal.

 

Check around the "freeze" plugs as well as you can- they're known to rot out from the inside when the coolant isn't changed often.

 

Go to Autozone and rent the radiator pressure tester.



You replace your radiator cap with the test cap. Using the manual
pump, pump up the pressure to 1 psi below what's labeled on your
radiator cap.

The pressure should hold. If the pressure drops off, you have a leak some
where. If the pressue holds, could be a bad radiator cap.


Autozone will refund your deposit when you return the tester.

 

Thats another great idea. Also you can take it to places like tires plus and have it dye checked. Or maybe you can get some dye yourself and do it.

 

Thanks for all the information. I'm going to first do the pressure test to rule out the cap and then look for those freeze plugs, I'm not sure where they are but I'm sure there in the DIY manual. Then the weep hole as well thanks again.

 

let us know what you come up with

 

Well here is what I found out. The cap was fine but a little rusted so for only 4 bucks I went ahead and replaced it. When I used the pressure tester there where two leaks. One from the thermostat that I replaced so I guess I did not use enough silicone that problem has been fixed I had to redo it. The second problem is I have the radiator that is half alluminum with nylon caps there is a very very slow leak coming from the driver side where the two meet. I know that there is an O ring in there but no one carries it. I'm going to try and squeze the clamps tighter and see if that stops it if not I might have to buy a whole new radiator unless someone else knows of some product out there that might help. Thanks.

 

squeezing the clamps tighter in that section will fix it many times . try that before you drop any stop leek in.

let us know what happens

Bruce