Radiator Overflow on my Towrig - Need Help

BRUISER

BRUISER

silent.. but deadly
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Ok I am not sure what is causing this but I need to get it stopped..

I have a '92 F250 w/ a 460 gas engine
with a 3 core radiator in it.

I have been driving it for the last 3 months with no problems and all of a sudden it started this 2 days ago.

I drove it to work about 30 miles and when I got to the parking lot the radiator started to over flow into overflow bottle which then filled up and then that overflowed all over the ground. While driving I never noticed the temp gauge get high, it was normal all the time.

So I got some water after work and refilled radiator and then drove home..this time I watched the temp and it never got hot.. it was normal all the time.. but when I got home it did it again... all over my driveway.

So I went to autoparts store got a new cap, drained all fluid and refilled radiator correctly and put new cap on. then the next day I drove it to work and the damn thing did it again..

Any Help or ideas what to fix would be much appreciated.
 
I think it's over filled. It's marked on the overflow tank HOT and COLD levels.
It may have been just warm enough to overflow from residual heat the first time this year. I'm sure this past winter you "topped off" the antifreeze which overfilled the system. Let it do it once or twice and DON"T refill it. As it cools back down it will draw the water back into the rad.

JB .02
 
I would say first change out the thermostat. If that don't cure it, I think the problem may be deeper as in a cracked head or blown head gasket. Are you positive the gauge is right? if it has already run hot and pushed out enough fluid, the gauge may be reading air temp inside and not water temp. Look for steam in tail pipe. look for water in oil. Look for oil in water. When you fill it back up, leave cap off and get it up to running temp and see if it blows out then. Also, have someone else turn the engine over with coil disconnected and see if you see the water rising and falling as it turns. If it does, then you have compression going into your cooling system. Hope this helps and I sure hope it is only a thermostat
 
hobie said:
What is that a sign of?

J
Click to expand...
Blown head gasket. Ken, replace your thermostat. It might be stuck open or close. (I would guess closed). Cheap and easy fix. Also another way to check for blown head gasket is remove the cap from the radiator, start the engine, see if you can spot continuous bubbles coming out.
 
I'm with upnover...even without oil in the water or vice-versa, a headgasket going bad or a crack can just pressurize the cooling system with combustion chamber gasses
 
id do a thermostat, just did on one my dd (heat started creeping up)

with a thermostat stuck closed you can be boiling over in the block and that creating the pressure making that mess...
 
Rockeater said:
I think it's over filled. It's marked on the overflow tank HOT and COLD levels.
It may have been just warm enough to overflow from residual heat the first time this year. I'm sure this past winter you "topped off" the antifreeze which overfilled the system. Let it do it once or twice and DON"T refill it. As it cools back down it will draw the water back into the rad.

JB .02
Click to expand...

Ya I tried this and when I open radiator is was almost empty.. and it is not sucking fluid back in from overflow bottle..
 
upnover said:
I would say first change out the thermostat. If that don't cure it, I think the problem may be deeper as in a cracked head or blown head gasket. Are you positive the gauge is right? if it has already run hot and pushed out enough fluid, the gauge may be reading air temp inside and not water temp. Look for steam in tail pipe. look for water in oil. Look for oil in water. When you fill it back up, leave cap off and get it up to running temp and see if it blows out then. Also, have someone else turn the engine over with coil disconnected and see if you see the water rising and falling as it turns. If it does, then you have compression going into your cooling system. Hope this helps and I sure hope it is only a thermostat
Click to expand...


Ok I wll do thermostat tonight and see.

as for gauge I have 2 in truck and the match :) so yes that is correct.

No steam in tail pipe...
No water in Oil..
 
Ken, it's fine so long as the truck is running? Got a numerical gauge? What's it say?

Then you shut it down, and the radiator boils over, right? What's the rating on the cap, and what does the temp read once the radiator starts spewing?

These new systems are designed to be sealed... if the cap is opening, there's something wrong. Fawk whatever marks are on the 'overflow' can.... it's just there to catch coolant when it overheats.

You might also consider renting a coolant system pressure checker from Autozone. They're about $100, but you can put it on your CC and return it later. It's got a little hand pump, you can check the rad cap and pressure check the rest of the system.
 
saf-t scissors said:
These new systems are designed to be sealed... if the cap is opening, there's something wrong. Fawk whatever marks are on the 'overflow' can.... it's just there to catch coolant when it overheats.
Click to expand...

I don't agree with this. I think most (all?) systems flow a little into and then out of the overflow reservoir every time you drive the vehicle.
 
BoltOnJohn said:
I don't agree with this. I think most (all?) systems flow a little into and then out of the overflow reservoir every time you drive the vehicle.
Click to expand...


False, over flow is OVERFLOW. Most do not flow back into the radiator.

Shawn??? little clarification..
 
I can't speak to ALL cars... but lots of newer ones, and especially the Ford in question don't open the cap until they're HOT (mine is around 250F before it generates enough pressure), and then the cap just shuts again once the pressure drops. It doesn't matter how much fluid is in the can, it's not pulling any of it back into the system.

Lots of older cars (50s 60s) used open systems that allowed fluid to run into an overflow can as it heated up, then pulled fluid back when it cooled.... but AFAIK, pressurized coolant systems (which allow for additional cooling ability due to the raised boiling point) did away with all that in the 60s with higher-performance engines.

That's all I know about the subject. ;)
 
Nope
85 CJ didn't have an over flow catch can, I added one only changing the hose, it does suck back in when it cools.
89 Honda civic does the same
86 Buick, does the same
89 Bronco, does the same
79 j-10 yep, does the same

Every one of my vehicles push fluid in as it warms, and sucks back into the Radiator as it cools.
With a sealed system it would have to have a large void like the old trucks and such for fluid exspansion I would think, and the ones I have messed with, do not. Granted, I have not messed with 90's and later.

I have been wrong, but the hot and cold line is there for a reason
 
If you don't believe me, Google can edumacate you.

What do you think that pressure rating is for on the radiator cap?
 
scarface said:
False, over flow is OVERFLOW. Most do not flow back into the radiator.

Shawn??? little clarification..
Click to expand...

No Absoluty Not. The Over flow in is where you are suppose to add fluid that is why there is a Hot and cold level . if the Fluid never went back in to the engine the there would never be a need to have those markings.
 
If either one of you can explain to me how a radiator cap that isn't designed to open until the coolant temp reaches 255F allows coolant to freely pass back and forth at 195F, I'll kindly STFU.

Until then.... :flipoff2:
 
I'd say it's broke if it does that. What kind of engine runs at 255F?
 
Maybe we should start from the beginning.

Modern cars (last 20yrs and certainly anything EFI) use thermostats with a nominal rating of 195F or so. That's because at around 200F, the combustion chamber is hot enough to completely vaporize the fuel. That increases power (complete burn) and reduces emissions. It also minimizes the unburned hydrocarbons that would otherwise accumulate in the chamber, exhaust valve, and exhaust port, causing additional wear as the deposits coke.

Now, we know that regular old water boils at 212F, so considering that the temperature in certain parts of the engine (exhaust valve seats, etc) is much, much higher than what the thermostat sees at the front of the motor, clearly straight water won't do. So we add ethylene glycol, which both raises the boiling point and lowers the freezing point. Convenient.

However, the boiling point of a 50/50 mix is still only 223F. A 70/30 mix EG/water is still only 235F.

That might do for a vehicle that's not making much power, since the thermostat has an added benefit of raising static pressure inside the engine (due to its obstruction of the flow). But for hard-working, higher performance engines, it's not uncommon to see 215F coolant temps at the thermostat.

And clearly, boiling coolant in the engine is very, very bad. While liquid coolant is an excellent heat conductor, steam is an excellent insulator.

The best solution then is to put the system under pressure. For each pound of pressure that liquid water is under, its boiling point raises by roughly 3F. How to raise pressure? Coolant increases in volume as it increases in temperature. If the volume of the vessel (coolant system as a whole) is limited, the pressure will rise as coolant volume attempts to increase.

So then, the entire purpose of having a radiator cap is to increase the static pressure in the radiator to a nominal 15#, thus raising the boiling point of the coolant an additional 45F.

Thus, if the engine is working exceedingly hard, and the coolant reaches a temperature (and pressure) that exceeds the limits of the cap, the cap opens to relieve pressure. It's a failsafe, basically. It opens to prevent excessive pressure from damaging heater cores, the radiator, hoses, head gaskets, etc.

When it opens, remember that it's expelling coolant that is over 250F, and well above its boiling temperature at atmosphere. Therefore, any coolant that makes it to the catch can evaporates rapidly.

Meanwhile, the coolant volume and pressure inside the engine have been reduced, lowering the boiling point of the remaining coolant further. Film boiling spreads rapidly through the motor, causing a further increase in pressure that continues to expel coolant, making the situation increasingly worse.

Basically, it overheats, and you're left on the side of the road.

So? There are probably a few systems out there that are designed differently. I can't speak to all of them.... but I doubt there are many that work much differently from this. At least, as far as anything in the last 20-30yrs is concerned.
 
Honda manual 1984-1991

All vehicles covered by this manual are equiped with a pressurized cooland recovery system. A white coolant reservoir located at the front of the engine compartment is connected by a hose to the base of the coolant filler cap. If the coolantheats up during operation, coolant can escape through a connecting hose into the reservoir. AS the engine cools, the coolant is automatically drawn back into the cooling system to maintain the correct level.

Haynes repair manual
Ford Taurus& Mercury Sable 1986-1995

Says the same thing, with the exception of a warning that the winshield washer fluid is part of the same container, not to mix the two up.

Chiltons Truck and van manual
Says the same with the exception. " pressure valveallows excess pressure out overflow, and vacum valve relieves when system cools"

Thats the newest books I have. If there was not a way for the system to draw back in either fluid or air, it would creat such a vacum that all the hoses would callapse , implode. because the fluid expanded when hot, and shrinks when cools.
Add to that, I have worked for myself on my on vehicles since I was 16. I have worked profesionally as a auto mechanic. I am 42, and the above is the same type systems I have incountered in all I have worked on except the VW bugs. I never had to work on a cooling fluid problem in any of those.
 
That's all fine, well, and good, upnover.

But you still haven't explained to me how the 195F coolant gets out of the radiator. ;)
 
With the radiator full and the coolant warming to operating temp it expands. This creats the pressure. Looking at my caps, all are 13 to 16lb caps. that is how it leaves the radiator. And yes the design of the cap and the design of the filler neck on the radiator does allow the cooling fluid to create the vacum nessasary to draw the fluid back in as it cools. If it did not allow it to escape, then Freeze plugs would fail, hoses would expand and burst. it's a cycle .
 
Ken,

Does the temp jump as soon as you slow down ? or just as you are toolin thru the parking lot at work and then erupt after shut down ?

if the thermostat were not opening, you would over heat long before you got to work ( no thermostat action means no circulation thru rad ) though it is possible that it is not opening fully.

I would also consider a water pump, impeller could be slipping on shaft, corroded away, water pump housing could be eroded internally from cavitation and at lower speeds not letting coolant flow at the proper rate.

Also consider that the fan clutch may not be working properly (or at all)which could also explain why it only happens after extended road driving and then a slow speed travel to shut off. ( notice any oily fluid at the fan clutch area or slung around the engine compartment ? ) If it is the fan clutch, spend the extra for the factory part, aftermarket pale in comparison in my experiance.

all of these things could have results such as you are experiancing.

can you let the truck idle for long periods and it does not heat up ? when doing this does AC on make a differance?

an IR (infra red) temp gun and checking various point on the engine could also help pin point a possible restriction in the cooling system. ( I can get hold of one monday if you think it may help)

Kevin
 
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