A 1979 F250 4x4 Custom
300-6


I've been driving my BMW for 22 years now, (big mud wagon), and it always ran cool.
Last year I replaced the radiator and recievied a bigger one which fit with only minor modifications. Since then the rig , when it does get warm, runs on the hot side. I have a 1700 foot pass to climb to work at an 8700 ele and it worries me.
Last weekend I put in a new 160 thermostat, , cap, and oil change. no difference.
If I keep it below 55 mph it is better, but still warmish. At 60+mph, even in the Idaho winter it runs warm.
After clearing the summit it cools and stays COLD in the morning. 45/ 50 degrees outside.
The afternoon climb gets to H, cools down on the descent, and then goes back to pretty warm.
Hoses looked clean, no constrictions.
Can the heat riser in the manifold cause this?
The riser moves freely, but makes no movement with acceleration.
Water pump? They work or they don't, right?
Sending unit?
Please, Thanks

 

So you are going by the temp gauge I presume?

Ford has trouble with gauges.

Do an actual thermometer check & check your engine timing.

 

What minor modifications did you do to fit the larger radiator?

 

I have the same problem with the same situation (used a larger radiator). I have come to the conclusion that it is too much radiator for the 300. When it is cold out it doesn't stay warm becouse there is too much water flow. When it is hot out the water flows too fast for the radiator to take the heat away. It is the only thing I can think of becouse it was the only thing I changed on the truck. In my case, I plan on using the truck for parts, soon, so it doesn't bother me. I think, becouse inline motors flow more air (less restriction behind the fan), a larger radiator is not really needed. My original radiator fell apart and all I had lying around were V8 radiators. Thats the only reason I went to a larger one.

 

What thermostat are you running? What brand?

 

I'm guessing the shroud or fan. Other wise are you sure the new radiator is clean inside?

 

I have a similar problem. I'm adding a shroud to mine. There are quite a few threads here addressing cooling issues too. Good luck.
jor

 

The fan shroud seems to be the most overlooked part of the cooling system. Without it the system just does not cool right, especially at low speeds.

Another overlooked part of the cooling system is all of those little rubber or cardboard flaps that are found around the radiator support. They are often removed during service or when they are damaged. They are also important parts of the cooling system. They block off air passages and force the air to go thru the radiator when the vehicle is in motion.

 

Cool, this seems like a good forum

Well, it's a Napa 160 thermostat, the only modifications were to drill 2 holes farther out to mount the radiator. As for being clean? I can watch the coolant circulate freely, how would yould tell if it's not clean?

I don't have a radiator thermometer, can you reccomend? I'm borrowing a mechanical guage set to play with. (my dash showed I have no oil pressure at idle, so I installed a mechanical one which showed the same thing) so much for tech solutions.



I am going by the dash gauge, and whether it's right on or not, it is a base point. (and yes I'm aware of the 2 volt rheostat on the panel, had to replace that 5 years ago and adjust it.)

Timing is set at 14 BTDC for high ele.

It never had a shroud on it, I'll look one up on ***

When it warms up in cold weather it stays warm to warmer.
It runs cool at low speeds, only over 60 mph on level ground does it go over midpoint.
But why does it go from close to hot in the morning trip over the pass and then stay cool /cold for the next 20 miles no mater how fast i drive till I reach the worksite and it idles for a couple minutes?

I also thought it might be too much coolant for the system to cool, amd have increased and depleted the coolant to no avail.

I am guessing thermo or dash guage at the moment, since the bitch always runs sweet. It ran pretty good today, 90 degrees air temp over the pass, and the sky was dark from the smoke from the local forest fire.
(The guage didn't go to H at 35 mpm. ( but to the L of normal).

I'll trade tips when i can, but the job is kicking my ***, work and sleep. Learning to fend off horse flies while operating a 70 lb jackhammer

BTW No smog controls , just a hose to distributor vac advance.

 

Those dash gages were never meant to last very long, 5-10 years or so... To make them work properly you have to go thru and clean every contact, solder every crimp connector, and coat every connection with silicone dielectric. Don't forget the ground side either. The biggest cause of failure in the instrument panel voltage regulator is corrosion on the ground reference point. The IPVR is a circuit just like your turn signal flasher. It supplies a pulsating 14VDC to the dash instruments that averages out to 5 volts, it is ON about 36% of the time. It varies with system voltage and ambient temperature also. Your gage readings will vary with ambient temp also. It seems to work well enuf tho...

 

Quote:
But why does it go from close to hot in the morning trip over the pass and then stay cool /cold for the next 20 miles no mater how fast i drive till I reach the worksite and it idles for a couple minutes?
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You're letting this mess with your mind.

Yes, IMO you are being made crazy by a gauge monitoring system.

One part of the engine says another part : "lets work this way for a while > Then we will change and drive this guy nuts"

Honest...... Engines talk like that about their driver's

I don't think you mentioned Blow out the overflow hose.

This what happens when the coolant gets too hot or When the rad has been filled TOO FULL.
Fill to 1" lower than the inner rad cap ring.


You can get a Candy thermometer to check the coolant temp.

The 160 thermostat should be changed with a 180*

This is just a Opening temperature for the T-statNothing more.

The engine probably runs around 205*F.

 

Isn't this a little too much? Initial timing that is too far advanced will produce a LOT of combustion chamber heat. Maybe dropping the timing down to 10-12* would help........

 

SERCZH,
What kind of motor do you have? it sounds like your running an "M" motor. They are prone to preignition. The hotter the motor runs the worse the preignition, the hotter it runs.
My guess is: you've deleted the fan shroud.
KingFisher

 

You might want to check your lower radiator hose, and be sure its got a spring inside so it won't colapse, I found out this the hard way with a cheap replacement hose.