After all the years I have owned this truck I have an issue I can't seem to solve. I have an '84 F-150 with a 302 and it has started overheating lately. I noticed it started running warmer and warmer a couple of months ago now it is full blown overheating.
I have cleaned and rodded the radiator, new radiator cap, new clutch for the fan, new water pump, new thermostat, new temp sending unit, new temp gauge, new regulator for the instrument panel, and new circuit board for the panel. No effect at all.
Does anyone know of any internal engine issues that I may be facing ie bad head/gasket, bad water jacket (bored out .60 over about 20 years ago) etc? Any ideas??

 

What is telling you it's overheating? Is the cap blowing and releasing billows of steam? Or are you relying on the factory gauge?

Factory gauges can't be relied upon for much of anything; I'd install an aftermarket temperature gauge, or maybe use one of those hand-held lazer thermometer thingers.

With the radiator cap removed, engine warmed up and running, look into the radiator and see if you can see the fluid flowing.

 

I'm having the same problem but my coolant is overflowing/boiling out from the resevoir

 

I am on my fourth gauge, two factory electric gauges and two aftermarket wet gauges. My truck used to run steady at 195 however over the last couple of months it's up to 215 and getting worse. My next try was going go test the radiator for CO2 showing a bad head gasket

 

Another way to check for a bad head gasket is a leak-down test.

Basically, you fill each cylinder with compressed air and look in the radiator for bubbles (one at a time).

Lots of info on it via google.

 

Do me a favor and start your own thread on your problem, would ya? It's lots easier to deal with separate problems when they're in separate threads.

Tell us the year, the engine & transmission, the symptoms you're seeing, when they started, what has been changed on the engine in recent history, anything you may have done to try and alleviate the situation, stuff like that, OK?

 

Yep, that's correct. Have recently done that and now know why my truck is overheating any time I drive above 40 - the engine is toast. Or, maybe I should say "toasted" as I overheated it.

Actually, you don't need to do a true leak-down test to find the problem(s). Here's the difference: A leak-down test puts air into a cylinder through a hose with a fitting that screws into a spark plug hole. The air passes through an orifice, typically .060", in the tool and the results are determined by taking the difference between a pressure gauge ahead of the orifice and one after it. Usually you'll put 100 psi on the upstream gauge via a regulator, so the results are easy to calculate. Let's say the downstream reads 80 psi while the upstream reads 100: 100 - 80 = 20 so that cylinder has 20% leakage. Not good but not BAAAD.

While the leak-down tester is a very valuable tool and easily built, I did it, just putting pressure into each cylinder while it is at TDC will tell you a lot. However, be careful since 100 psi with no restriction has a lot of power and can easily turn the crank if you don't have the piston exactly at TDC.

Anyway, in either test you listen through the carb for air escaping, in which case you have an intake valve leaking. Through the exhaust for that valve, and in the PCV hose for leakage past the rings. As for the cooling system, if you have a cracked head, bad head gasket, or cracked block the results will usually show up as either the bubbles ctubutis mentioned or as coolant being forced out of the radiator cap as in my case.

 

Well I am not sure how I fixed it but I put yet another (3rd) thermostat (180), another temp sending unit, and bled in accordance with the shop manual and low and behold it seems to be running fine and yesterday it was 100 degrees.

I never got to the exhaust gas leak check but I ran a compression check and everything there seemed to be fine. I did pull those bosh platinum 2's for regular bosh platinums. If for no other reason than it was time. I wasn't sure if those plugs with this MSD ignition system would cause a higher combustion temp or not but it was worth the try.

Anyway it is good to get it back on the road.