I have an 83 F150 with a 351w engine and I started having overheating problems a few weeks ago. It is all original equipment and has about 160,000 miles on it so I already sort of expect some things to just wear the heck out anyway but I've been lucky with it so far.

It started where it would run a bit hotter than normal on the gauge, but when I stopped the radiator would be spitting or the overflow tank would be spewing. It got to where after stopping if I did not let the engine cool for 20 or 30 minutes it was almost impossible to get it to crank. I flushed the radiator and ran BARS stop leak through it as well as a water pump treatment and it seemed to run a few days fine like that so I thought the problem was solved.

However a few days later after about 15 minutes of driving the temp guage shot up while stopped at a light and continued rising more slowly during driving and eventually overheated and stalled. Of course at that point what was left of the coolant in the radiator steamed up.

Previous experience told me that this might be a faulty thermostat so I replaced that. It appeared that this also seemed to be a fix as well as I idled it and drove it around about 25 minutes and the temp stayed around where it normally runs (halfway up the R or so and sometimes around the M idling after a long high speed drive).

However the next trip I took at higher speeds (excess of 45 mph) it again shot up at the first idle and continued rising to the point of overheat. The radiator was steaming and spitting, and on refill it continued to steam up until I had gotten a couple of gallons of water into it. After it had sat through the work day I did manage to get it home by stopping and letting it cool down halfway through the trip. Once home, the radiator again steamed what was left of the contents of the radiator out the grill. If I refill it cold there do not appear to be any leaks, though of course when it is steaming and sputtering there are drips and spews coming from all over the place.

The water pump is working, I have watched the circulation start while idling and it runs fine at idle. The next thing that I can think it might be is the fan clutch. I have noticed that even after reving the engine for 7-10 minutes the fan speed never changes, and the thing is extremely filthy.

Does the fan clutch sound like the likely culprit to anyone else? If not any suggestions? I love the old dog because it is the only pick up I have ever owned and the body / interior are in great shape for such an old monster....but I swear if it were a horse right now I'd probably shoot it!

(Oh yes one other thing: there is a small compression leak from the valve outlets where a bolt had cracked off during tightening, but other than cutting the power down a little bit and cutting down on the kind of mileage it should be getting it hasn't cause a problem in about 8 months 50k miles of driving)

Thanks for any help!

 

Hello GreyFordFan and welcome to FTE!

I would take a hard look at the fan clutch. If it spins easily with the motor off it is toast. I would also complete a pressure check of your system and see what it shows. Try those first. It may be possible that your radiator is plugged internally and will need to be replaced or throughly cleaned out.

There are several threads posted here with similiar themes to them. Looking over them might get you going, if not there are plenty of people here who can help you out.

 

Well I can push it around very easily, like by the fingertips and recently before this all happened a squeak had developed that sounded like a belt but wasn't because I checked the tension on them with a screwdriver.

Should the fan have more resistance than say a 2-3 pound push with your fingertips? I would think so but I don't know since I really don't think I've ever driven anything with a fan clutch. It IS my only vehicle so doing the right thing for it the first time out is kinda critical.

Thanks!

 

It's worn. Normally, you have to really push hard on the fan and then it either slips on the belt or you start moving the engine. Pushing a fan should be tough. Sounds like yours needs replaced.

 

Thanks! I was sort of at my wits end with it. Since I was able to flush the radiator clear just a few weeks ago I was pretty stumped and until I got out the Haynes I had no idea that there was a fan clutch on there. Glad to know I was at least headed in the right direction.

Looking around I see that there are two kinds Thermal and Non Thermal as well as ones made with or without AC.

Which works better? Also can I bypass the air compressor (does not work) via belts and but the much much cheaper without AC clutch?

Again thanks a ton...I feel better about the monster already!

 

Someone suggested that I bypass the clutch all together and put a high perf fan straight onto the water pump pulley? What would this do all together? Better or worse for cooling / milage / ect;?????

 

Several users really like them. Basically it comes down to what you think you need. You are splitting hairs at this point IMHO. So long as you have a good shroud, anything you install should be a improvement.

You can also bypass your air compressor but it's probably not worth it for a number of reasons. It will be difficult to find the a belt that would fit and the distance between pulleys may be excessive (say distance from the crankpulley to whatever) causing the belt to vibrate a lot.

 

About halfway there. I went ahead and put in a high perf flex fan and from idling for 20 or so minutes it's a drastic improvement. Just barely gets to the normal marker on the temp guage and I can actually stick my head under the hood without feeling the heat. Good call on that fan and one less part to break IMHO (plus it only cost $30 vs $80 or so...oh yeah!)

It's also idling better than it ever has so I guess that clutch had been working on going out for awhile and dragging the engine down with it.

BUT......

It's still spitting coolant when I give it some gas Hot coolant...bubling hot coolant.

It does it with all mixtures of coolant 50/50 - 70/30 and with plain old tap water. That is very puzzling to me. I would think if there were a leak in the radiator it would leak all the time. I don't think the water pump is out because the intake hose gets warm as the temp shoots up so there must be coolant flowing (right?).

Any idears???? I'm about to go run BARS through it a second time (I know some people think it's bad stuff but I've had good luck with it in the past). After that I'm stumped.....

Thanks for helping me keep my monster alive guys!

EDIT:

Oh yeah about bypassing the AC....pffftt that was a snap. Aftermarket AC on it's own pulley and idler. Loosen the idler...bye bye belt. Bet that's gonna help on the milage some too =).

 

Bleh.....water pump too.

'Circulating' water was water circulating off the top of the radiator and back through. Once the temp under the hood got hot enough it boiled it out.

Looked convincing enough though

One thing I will say though about that flex fan....it kept the engine way down below the 'o' on about a 25 mile trip before I figured out that what I thought was the water pump circulating was actually the radiator burbling on its merry way. That's pretty impressive cooling power I think.

After I get done under the hood on Sunday I'll post some pics of it if I can. I think the FTE group would be pretty impressed with my $500 160k mile ford monster.