Everyone I am in need of some desperate help. I have a 94 F150 with the 5.8L engine, and I am having some heating issues. I have flushed out the radiator, put in a new thermostat, replaced the fan clutch, and heater coil, and this truck is still overheating. Is there something that I am missing, or should have done? Any and all help would be greatly appreciated.

 

just take the hood off like roadkill.

 

Eh, most everything you mentioned sounds reasonable so far, tossing these out for consideration -
1) How do you know it's overheating? Possibility of a gauge / sending unit issue?
2) Fan belt routed properly so that the water pump is turning in the correct direction?
3) How much crud came out during the flush? Possibility of a still-restricted radiator?
4) Possibility the water pump impeller is worn or failed? When the thermostat opened, can you see the flow in the radiator fill opening?
5) How are your radiator hoses? Possibility of the lower hose collapsing, restricting flow?
6) Possibility of a bad thermostat before, and the new one installed upside-down or just bad out of the box? (Stretching, I know - but don't know your level of mechanical ability...)
7) Airflow blockage through radiator. Is the fan able to pull a good draft through?

Hope this helps...

 

I would lean towards the water pump. That was my culprit when I started having problems and did all the fixes that you have done.

 

Thanks, any and all things help. I have been really frustrated with this ever since i got it. PO said that a new temperature sending unit was installed (however i doubt it, as he also stated a new thermostat was put in and there wasn't even one in there). The belt is routed correctly. A lot of stuff did come out of the radiator during the flush ( I think there is more in there, and do plan on replacing it). And i also know that the upper radiator hose is collapsing. The fan is pulling in a food draft as far as I can tell. The water pump maybe bad as well. I will dive more into these thing tomorrow and post what I have found.

 

The upper radiator hose should not be collapsing. It is where coolant gets pumped to the rad.
The lower one can collapse if there's a problem, that's where coolant gets sucked from the rad into the motor - that's why quality lower hoses have a spring in them to keep the from collapsing.
If your upper one is collapsing I would seriously consider what wde3477 said about improper belt routing (water pump going backwards).

 

Aftermkt hoses collapse(parts stores.) The Motorcraft one has a spring inside it, aftermkt stuff has never impressed me.

Note that for the coolant sending unit you mentioned had been replaced. Unless it was a Ford one, new doesn't mean good. Highly unlikely but you can use a temp probe for cooking, had for a cheap price, just put the temp probe tip against the radiator hose, it can give you a good reading within a couple degrees.

Since the truck had cooling system repairs before, it might have air in it. Point the truck uphill, however you can, higher the better, leave the cap off when its dead cold, then start it up, let it work the air out while its warming up with no cap on. I've even held up cars with backhoes before or parked them on a steep hill. Pinhole leaks will cause air to get in, as well as a leak that is super hard to find.

Water pump is maybe, ---------------------------------whats the mileage on the motor?------------------- Again, don't go aftermkt, gaskets either, maybe some higher end Fel-pro's are ok, get the water pump gasket maker/sealer also.

Worse case senario, the guy running with no t-stat got it hot and something more internal/gaskets has let go, no t-stat is for drag cars, never a good idea for street use. Buy a NAPA "block tester." It

Radiator flushes move stuff around, cause blockage. Unlikely the cause, since you had over heat probs before. Flush it again tho, never know....

Radiator cap replacement. This is just the same as a hose with a leak if its faulty.

Trans fluid, engine oil can cause heat if its too used or low.

--------Timing too high can cause it to run hot as well.---------------



One thing at a time, remember that.