Radiator overflow, overflowing (1 Viewer)

[wchevron]

Hot today 90's and humid. Drove the truck home from work, about 25 min on the highway. Got home and heard a bunch of gurgling from the engine. Opened the hood and noticed the radiator overflow was gurgling and some antifreeze had leaked out. Guessing it happened while driving, everything below the tank hose was wet and some even on the side of the battery. There was only a couple of drops on the garage floor so I'm thinking was overflowing while driving. Temp gauge was hovering on the line right to the left of the H. Never went over that line. Not really sure what I should do about it.

 

[igotta40]

I would start with a new radiator cap, if its present condition and age are unknown.

 

[brian]

So if it was at that line....it was hot.
Hot enough to call it an overheat.

 

[pb4ugo]

Do you have someway to get an actual temp reading? IR gun or a mechanical gauge. It sounds like you dont have a recovery tank. A new cap to start is a good idea. Without a recovery tank and a topped off radiator it's going to release fluid until it finds its happy place, if everything else is operating properly.

 

[rlong]

Also, the temp tends to shoot up when you stop; no fan or water pump running; in engine heats up and expands. You can watch it with a manual temp gauge. But yes confirm the cap, might be an anomaly; cars are not as consistent as we would like!

 

[wchevron]

So if it was at that line....it was hot.
Hot enough to call it an overheat.

View attachment 3959752

Yes, was at that level while driving

 

[pb4ugo]

50/50 A/F and distilled water lowers its boiling point. Fluid under pressure raises the boiling point. If the cap is weak or the rubber seal is compromised it can't keep proper pressure in the rad and lowers the boiling point and can blow coolant. As @rlong mentioned temps will spike once the engine is turned off. It sounds like your normal operating temp is high. Try a new cap if its old. Beyond that, new Tstat, flush rad. Maybe flush block. Check timing etc.

 

[65swb45]

Direct drive or clutch fan?

 

[wchevron]

I'll order a new cap. Can I get a generic cap at Autozone etc. Or are radiator caps specific and I should get a '40 specific one? Let it cool down and took the cap off. Coolant is right up to the top. Took the cap off the overflow tank. It's empty. Should I fill it to the Low level or Full level?

 

[pb4ugo]

When cold it should be at the lower line. When the temp rises it build pressure and forces water out to the overflow, when it cools water is sucked bsck in. The tank needs water in it so it doesnt suck air. A factory cap for your application is probably best. You can get a aftermarket one as long as it's for your application.

 

[charliemeyer007]

If the cap doesn't function correctly it can let coolant out early and/or fail to let it get back sucked into radiator. The hose and fittings on the tank and radiator need to be good too.

A failing thermostat could make it overheat at times.

+1 liquid cooled engines will get hotter for a while after you shut them off.

You are on the road and it starts heating up - turn on the cab heaters, shut off air conditioner and all the lights you can. Pull over and take your water bottles and squirt them into the cooling fins - then take off again and watch the gauge.

Wash out the cooling fins of the radiator from the engine side - de greaser might help. I have fine mesh bug screen in front on my radiator to help keep trash out of the fins.

 

[45Dougal]

If you lost fluid, but its still at the top, then you may have air in your system now.

Id also start with the radiator cap. I had this last year where the outer seat was slightly damaged, and wasn't sealing. In effect, it could blow out, but not suck back.
Both seals need to actually seal.

Also worth checking for oil in your water, and water in your oil though.

 

[wchevron]

Added some antifreeze to the overflow tank. Another hot/humid day today so will keep an eye on it. I have noticed before, when the temp gauge gets up to that line before the H, If I end up off the highway and on some side roads for a bit and going slower and the engine rpm are down, the gauge will drop down fairly quickly to almost the center of the gauge.

 

[wchevron]

Just drove in this morning. About 25 min. Low 70's and humid. Gauge was a bit more than halfway between the two hash marks. Was leaning towards the H hash mark but a bit before it. Brought my infrared gun with me. The top cap/header of the radiator was 200*. The top fins that are exposed when you raise the hood were in the 190's. About mid way down the fins were 180ish. Down at the bottom of the fins was 165ish. Not sure if the radiator is supposed to be even temp all the way down it but bottom is definitely cooler than the top. Not sure if it needs to be flushed?
When I bought it about 1.5 years ago, I did dump all the coolant. I had pulled the cabin heater to refurbish it. Bypassed the heater and refilled the system with water for that whole summer. Then in the fall, dumped all the water, installed the heater and refilled with antifreeze, which has been in there less than a year at this point. When we dumped the antifreeze the first time, it looked pretty clean.

 

[pb4ugo]

It sounds like the rad is working. Everything you described is how the cooling system works. Hot water enters from the engine and cools while it flows thru in rad. Then re-enters the engine.
Here's a ballpark guide to the guage temps. Stk gauges are typically not the most accurate.

Try a new cap 1st. What yr 40 is it? Can you answer Marks question.
The fan clutch should kick in/lock up at high temps to provide more cooling.

Direct drive or clutch fan?

 

[wchevron]

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.

 

[pb4ugo]

Its a mechanical fan, no fan clutch.

 

[65swb45]

SMH

It’s a time bomb.

 

[wchevron]

Can the mechanical fan be replaced with a fan clutch?

 

[rlong]

Thats an aftermarket flex fan, blades “flatten out” at higher temps. It is a poor substitute for a conventional fan and clutch because it adjusts only for engine speed not temp. I am not versed on how to convert to a (more modern) plastic fan and clutch but believe it is done.