Radiator overflow, overflowing (22 Viewers)

[wchevron]

I try to keep right at 3000rpm. Maybe up to 3200 for a bit but try to keep it at 3k. Not sure on the gearing. 1977, 4 speed. I know the engine and transmission were replaced at some point it the past so not original.

 

[65swb45]

Just installed a correct sized fan/fan clutch so I don't think that is the issue.

Going to try the 160* stat and new sending unit. Was also thinking of giving it a flush. When I was running the temp gun along the radiator, there would be a spot or two that would be 20-30* off the rest in the same elevation. Thinking maybe there is some partial blockage in some of the radiator passages When I pulled the heater last summer, there was a lot of crud in the heater core.

If the tstat doesn’t remedy the problem, then it’s radiator time. Either have yours rodded by a shop, or spring for a new one.

 

[BullHab]

I try to keep right at 3000rpm. Maybe up to 3200 for a bit but try to keep it at 3k. Not sure on the gearing. 1977, 4 speed. I know the engine and transmission were replaced at some point it the past so not original.

I forgot to ask your tires size. Oh well my 78 FJ40 with a four speed and 4.10 gears, with 285/75-16,(32.8" tire) is doing approximately 72-75 mph at 3000rpm. I use that as my top rpm. My temp gauge reads almost to the line yours is at. My hand held temp reader indicates 193-196 at the bottom of my thermostat housing. 180ish as the highest taken any where else. I am running a brand new 4 core Aluminum radiator and electric fan. Dropping my speed to 65ish and 2700-2800 rpm drops temps to middle of the temp gage upper scale and 183 temp reading.

 

[peesalot]

I am shocked nobody has mentioned the fact the fan is crooked, only has 2 bolts, the truck should not be run like that. The pulley for the power steering is wrong, misaligned, and uses a belt too small for the water pump groove. Nobody mentioned opening the radiator drain ? Have you checked the alt & power steering to see if the bearings are going, causing extra work to engine, increasing heat ? Is it running lean ? they'll heat up under that condition as well.

 

[wchevron]

@peesalot , Just when I thought I was getting to the bottom of my overheating issues, you throw a wrench into the plans. The old fan was actually on with 3 bolts, I guess the PO thought the hole for the 4th was a spare. I did replace it with a correct one, and I used 4 bolts.

I was curious about the power steering pulley. Thought it was odd the way it was cone shaped rather than a flat pulley. I had to replace the allen bolt at the end with a different bolt which had a shorter head. The new fan blade was hitting the allen bolt head by about 1/8". Been running this way since I bought it 1.5 yrs ago. Was going to bring it to my local shop in the fall to have some other work done. Will have them inspect items you mentioned. Thanks for the heads up.

Picture of the old fan blade and the new one. Was probably 1-1.5" shorter diamerter than the new fan blade. New blade fits the shroud much fuller than the old one.

 

[peesalot]

Don't be suprised if you have to barely trim the tips of the blades to clear shroud, I cant remember which combos require that.

 

[wchevron]

Already got it in. With the bigger fan blade it was rubbing along one side of the shroud. Was able to oblong the bolt holes and slide the shroud over about 1/4" which cleared everything.

 

[peesalot]

FWIW, given the symptoms, you may have restricted flow, could be thermostat, pump, radiator ? If you look thru wngrog's threads he sorts the pulley, power steering pump, belt issue, IIRC there is a pulley for the ps pump that fits the wide belt.

 

[BullHab]

Thanks. Going to try to grab a new cap today or tomorrow. Not sure on the direct or clutch fan. Took some pictures of what I have. Truck is a 1977, 2F engine.View attachment 3960189View attachment 3960188View attachment 3960190

I would suggest a new stock clutch fan.

 

[BullHab]

Fan blades and airplane wings have a lot in common. Blades and wings cut through air, the resulting higher pressure on one side pushing air (bottom of wing, engine side of fan) causing a difference in pressure, lower pressure on the other side (top of wing, radiator side of fan.)

From this pressure difference, the air below the wings (blades) rolls up and wraps around the top of the wing (blade), causing a whirlwind named a wingtip vortex. In other words, some of the air pushed by the blade towards the engine rolls back and flows into the low pressure side of the blade.

According to NASA, "The effect of these vortices is increased drag and reduced lift that results in less flight efficiency and higher fuel costs." For a fan blade, this means less air flow through the radiator. Airplanes reduce this vortex using winglets flaring upwards on the end of the wings.

A properly positioned fan shroud would reduce this "wingtip vortex", improving mass flow through the radiator for better cooling. This allows for less aggressive fans, which use less parasitic horsepower to turn a mechanical fan.

On the other hand, more hp hungry aggressive fans don't need shrouds.

If shrouds weren't important, why would automakers use them on every car they build?

Automotive Engineers aren't known for adding unnecessary or costly items to a vehicle.
I did like your explanation of "Little Bernoules" on a wing/airfoil.

 

[BullHab]

You may have had air in the system and when it cooled down it sucked in more a/f.
Fill the res to the lower line again and cycle it again.

I normally fill the reservoir to the full mark and let the system find its equilibrium. Wastes a little coolant but you are assured the system doesn't suck air.

 

[BullHab]

Find a steep ramp - park on it - remove the radiator cap, top off fluid - run engine for a while until you see serging/fluctuation in the level of the fluid - the thermostat is opening/closing. Clamp off one of the heater lines to the front heater for a few minutes - this will force flow to rear heater; move clamp to rear heater hose. Your cooling system should be bubble free. Put on cap, fill tank like 1/2 way. As the rig fully heats up, coolant will be pushed out of rad into tank. When it cools back down, fluid will be sucked back into rad if everything is working correctly.

Great method to "burp" the system. I usually just jack the front of the vehicle up in the garage....

 

[pb4ugo]

I would suggest a new stock clutch fan.

What's wrong with the one he's has?