Equipment: 1979 F350 Flatbed
351m engine
2 wd - short wheel base with 9' bed

I bought this old truck 3+ yrs ago, I noticed right from the first that it seemed to run hotter than it should.

First thing I tried was removing the thermostat. I didn't see any noticeable differnce once the engine was thoroughly warmed up. It still ran around 180-195. And hotter still on hills or pulling a trailer.

I put a new radiator (not rebuilt or reconditioned), and a rebuilt water pump on it, as well as cool 170 thermostat. It still runs too hot. With or without the thermostat.

I began to think maybe the heat reading was not accurate, and so put on an aftermarket heat gauge. One of those where the sensor runs from the engine clear to the dashboard. Not the electrical kind.

The new meter shows the same as the original equipment heat gauge. Or at least close.

In my experience with other trucks, including a similar 1983 Ford F350 with the 351-400 engine, it should run fairly cool, like 160 or so.

The old truck has been idle for about 2 yrs. I'd only run it around now and then.
It would sit all winter, only being started and warmed up a few times over the winter.

In the last few days I drove the truck from Gary Indiana to Atlanta GA. Some 700 miles.

About 300 miles into the trip (that is, once it was fully daytime). I began to see heat at and above 190.

And once I got into more hilly terrain, I would see it heat up on the hills. Once the outside temperature was 80-90, I'd see it climb as high as 200-210.

Then when I'd roll into a service station for gas, it would go higher still.

I never had a real boil over, just a little squeeze out through the over flow pipe. Maybe 1/2 to 1 cup of fluid, but still it seems to run way too hot.

The last 2 hundred miles it stayed around 195 - 200, only dripping below 190 on nice flat stretches. (or downhill)

So to recap for a moment, I put on this new or rebuilt equipment:
New Radiator
rebuilt water pump
cool or no thermostat
after market heat gauge.

With that big new radiator and a working water pump, I'd expect the engine to run cool.

So now I'm wondering what else could cause the engine to run hot?

I've heard over the yrs that ignition timing being retarded can cause an engine to heat up. But before I start mucking around with the distributor when I'm 100s of mi from home I wondered if someone here could tell me if that is likely to cause this kind of overheating.

Somewhere around 500 miles into my trip, I did try to loosen the distributor and move it a little, but I found that I could not move it either way, even after a few raps with a screw driver and light hammer into the base.

There is so much junk around the distributor in the way of plug wires, vacuum lines, fuel lines and heater hoses that I've been a bit reluctant to start monkeying around with it. Other times I've messed with a distributor, once it was loosened I could stick a screwdriver horizontally through the raised plug wire ports on the cap, and easily turn it.

Now I'm at some of my families' place in Atlanta I can work on it a bit without fear of being stranded out on the road. Although I do need to drive it back home pulling a gooseneck trailer

The distributor body seems to be frozen in place, but I haven't cleared stuff out from around it, and really got serious about turning it yet.

I guess I'd like to hear from someone with more experience, if that is likely to be the problem before I try getting a small pipe wrench around the neck of the distributor and seeing if I can free it up that way.

The truck seems to start and run OK, so I'm guessing the timing is at least close. I'm wondering how far off timing would need to be to cause the engine to heat up. And if I would be able to correct it by making very small increments as I drive it around, testing to see if the heat starts to drop off.

 

Most vechile I have had run about 200-210 normal. But try you Rad cap.

 

Is the fan shroud still there or has it been removed?

 

What about your fan? If its a clutch style, while the engine is off (obviousley) grab it and check for up and down movement in the hub. If the clutch is shot it will not be spinning at max speed. Or if it's an aftermarket fan, it needs to be the right size. If their is too much gap between the edge of the blades and the shroud it will not pull enough air through the rad. And of course a shroud is an absolute must

 

You need to make sure the timing and advance is right.

 

190 is a completely normal temp. 230 is the start of the danger zone. Hill climbing at 210 in warm weather is defanitly not abnormal. I would do a regular service. Change your antifreeze, and buy a new radiator cap. As long as your truck runs good, doesnt hard start when warm or ping under load your timing should be fine.

 

I'm not loosing any fluid. (other than about 1/2 -1 cup - probably from over filling)
Which would seem to rule out the cap.

I haven't seen the kind of temperatures you mention in my experience with the following Ford models and engines.:

I've owned:
1983 F350
1979 F350

1983 E350
1974 E250

And my current 1998 F150. Not really sure which engine but I think something like 283.

Both older F350 Trucks had the 351/400 and the vans had the 351Windsor.
Except th 1974 which came from the factory with the windsor but I put a 351c out of a cougar in it. (After splicing together the two oil pans since the sump on the cleveland is in the wrong place to go in a van).

The 1998 F150 runs cool as can be.

Out of that bunch, only this 1979 F350 has run hot.

The others rarely going past half on the heat gauge. And I've never seen the 1998 F150 get close to half.

Can anyone else offer input about the 351m engine so far as running hot?

 

I've got a Supercab with a 351m and it runs warmer than I'd like too. I pulled the thermostat and helped a little, but not much at all.

I think my issue is fan related.

 

Yall really shouldnt be pulling the thermostat out trying to fix an overheating situation. Thats not the way to go about it.

 

Yeah I know but as Pops always said "Poor people got poor ways" haha

I've got a new stat to put in it but just havent had time to get to it.

 

Those are very normal operating temps. I've never had a vehicle that ran at 160°. A hotter engine is a more efficient engine (as long as it's within a safe range of course). Everything I have runs at least 180°, my 76 has a 192° t-stat.
225 starts to get dangerous as that's the temp that most of these boil at, but anything 210 and below I wouldn't be worried about. The temps and corresponding driving conditions you're getting sound just fine.

As mentioned do you have a fan shroud?

 

I repeat myself. And those temps may not be far off.

 

This is a non-issue, those temps are completely within normal operating range under those driving conditions.

 

over 210 is danger danger danger!!! my dad has been a mechanic wrenching on cars and working and shops since he was 14... he is currently 60.. my suggestions for u is to check the fan clutch.. the way u do this is let the engine warm all the way up and watch the fan when u shut the engine down it should stop with the engine. or if you are missing the shroud that will do it. the car u see in my avatar is a car my dad built back when he was 17

 

pullin the thermostat out in some cases can actually cause it to because the hole is so big the water pump can no longer create enough pressure to push the water through the radiator

*edit* disregard this post my brother told me that and now hes tellin me it wont let it get hot enough