hello,
I have an 86 f250 with the 460, and it constantly is overheating. I've replaced the thermostat, the radiator and now the water pump. I've flushed the system multiple times and it still over heats. Any ideas on what could be causing it?

 

Do you overheat going down the road or at a stop? Radiator shroud installed? Do you still have all your coolant? Finally, check that the lower hose isn't collapsing when the engine is running and at operating temp (when your thermostat opens). Honorable mention is checking the thermostat is going the right direction where the spring is going into the manifold.

I have had cooling issues for a long time with my 460 till I finally put a fan shroud on. There have been a few failed components before the shroud that also cause issues for me. So if you are loosing coolant look for leaks when the thermostat is open.

First was an expansion plug behind the motor mount had a pinhole rusted through it and finally gave way when I ran a flush through the system. Those flush in a bottle products can break up rust in coolant passages causing a clog or uncovering a leak. I was using tap water for a good long while so that damage was self inflicted. A proper flush should just be a coolant exchange I have learned concerning my motor.

Second thing that failed was the heater bypass hose that goes between the intake manifold and water pump. It too sprung a leak from the hose right at the clamp. Took two different attempts and tightening the clamps to get it fully sealed.

 

It over heats while driving, slowly but gets to the point where the engine will sputter for a few seconds after I shut it off, the spring on the thermostat goes into the manifold. And I haven't noticed the lower radiator collapsing. Coolant levels have been consistent, no leaks or burning any that I've noticed.

 

Sputtering after shut of is somewhat normal. Dieseling I think is the technical term.

Where on the gauge does the needle land when you say it is overheating. 460s like a higher temp (about 195) from what I have read. If you have or get your hands in a temperature gun, you can read the temp of the thermostat housing after the thermostat is open.

Speaking of open thermostat, you could test your thermostat in a pan of boiling water to see if it opens at the advertised temperature.

As far as the lower radiator hose, from the factory they came with a coil of wire inside to keep it from collapsing. Most don't keep or even think/know about the coil inside when they get new hoses. If you the have original hose, you might try to squeeze it to see if you have the coil in there or not.

 

I'll check the hose, but with a temp gun the thermostat housing reads 200. But the factory gauge and an aftermarket gauge both say its over heating. The aftermarket reads well over 250

 

Yessir, that is hot.

If the lower hose is good, then you might have a blockage somewhere due to the flush. Not sure what entails trying to clear passages. Air compressor comes to mind but unless you want to tear into the motor, not sure what other options there are.

See what other members here might have to say. Sorry I am not of more help. Good luck!

 

The lower radiator hose doesn't have a spring, would any parts store (that has the hose) also have the spring installed. Or is that something ill need to find?

 

You will have to try your luck at a junkyard. However if you can witness your lower hose not collapsing then you should be good there.

I would get a bright flashlight to point down there and then have a helper in the cab holding the throttle down to about 2500rpm. You'll have to guess based upon engine sound if you don't have a tach or if you have a timing light with a tach readout, that works great. Again, make sure the engine is already at operating temperature.

 

On this spring and lower hose.
At idle you will not have an issue with the hose but when the RPM goes up the hose gets sucked closed and flow stops and why the spring is needed.

You can try a new hose and see if it will have a spring but I don't think it will.
My 300 six also did not have a spring in the hose and the new hose did not come why one.
I bought a flex hose that had a spring inside I thought I could pull out and install into the new lower hose.
It was a fight but I got it and so far no issues when driving and most of it is at high way speed.

You could have mud sitting in the bottom of the block and even flushing will not get it out.
I have 1 motor that is why it was parked and that is after 2 radiators, water pump, hoses, many flushings and even added a shroud that was never a factory option.
The shroud help it just took longer till it go to hot to run with out harm.

Also had a buddy had the same happen with a used motor he put in his CJ Jeep. It would over heat, his fix was to rebuild the motor and the hot tank broke up the rust.
Dave ----

 

I was going to say it will be hard to witness the lower hose collapsing, unless you get it hot, and then possibly rev it really high in the driveway while you are looking at the hose to see if it sucks shut.

Overheating sitting in town is a airflow problem. Overheating going down the highway is a coolant flow problem. No spring in that lower hose is definitely a problem.

 

Just checked Napa. They call it a steel coil and it's not included with the hose.

 

Here's one that fits many different vehicles and trucks. Yours is not listed but it might be better than nothing.

https://www.npdlink.com/product/spri...se-from/143875

 

For any cooling issue, I’d suggest some basic diagnostics. Take care of that missing spring in the lower radiator hose first. If the problem continues:

Pressure test the cooling system, with one of those testers that look like a bicycle pump. Make sure the system can hold its rated pressure for at least 15 minutes.

Pressure test the cap, too.

Make sure the cap can seat properly on the radiator neck. Inspect where the cap seats inside the radiator neck.

Check for the presence of combustion gas in the coolant. The easiest way is with a special tester that looks like a turkey baster.

With the engine at idle, hold a rag or sheet of paper in front of the grill. With proper airflow from the fan, the rag or paper should be held tightly.

At idle, engine warmed up, take a temperature reading at the radiator inlet and outlet. You should see a temperature drop of at least 30F.

Many auto parts stores have free loaner tools for doing these checks.

 

+1 on that. Heck, +infinity! I’ve had several thermostats bad right out of the box. Different vehicles, different brands, didn’t matter.

I have finally wised up and always test a new one before installation. I always test the old one, too, just for confirmation before replacing it.

My impetus: I had a thermostat fail in service on my car after several years. No big deal, I popped in a new one and it was bad from stock. It misbehaved exactly the same as the old one. Talk about a troubleshooting nightmare! It wasn’t until some serious headscratching and precision use of foul language that I finally realized all symptoms still pointed to a bad thermostat. I tested both and realized what was happening. You can be sure I tested the next replacement before installation and then all was good.

 

All you have to do is start the engine and let it warm up while checking the upper radiator hose with your hand. At first it will be cool to the touch. Once the engine gets to around 200 F, the top hose will suddenly get hot. If it does, then the thermostat is working.