The Stovebolt Site Forums The Parking Lot Big Bolts 235 - 52' - 2 ton - water pump or thermostat?

Brand new radiator, idles for about 10 minutes and the radiator gets hot. Top hose hot, bottom hose cold. Any ideas? Water pump? Thermostat? Air? Any help would be great. Thanks!

Did you test the thermostat in hot water?

No, Everything was good prior to the new radiator... How do you go about testing in hot water?? I assume take it out - dunk it in a bucket?
Thanks.

yes

Some things to check:

Did you put the t-stat in the right way? Older t-stats are hard to reverse due to the size of the wax housing/bellows. New ones can easily be put in upside down.

Did you use a water pump adapter plate? You have to get the balancer to pulley ratio right or it may spin to fast (esp in low gears) and cavitate.

The impeller is pressed onto the shaft and it could be slipping or the 'fins' on the impeller may have deteriorated due to cavitation/age.

Thanks... haven't touched either the T-stat or water pump and as I say, they were working fine last season. All I did was empty system, swap old radiator out with new, refill and upon firing up - the symptoms have begun.

Pinch

Air in system?? As I'm reading some older posts?? drill bit?? And where?, what to plug with when done? Any pics if indeed this might be the case... maybe a good subject for a tech tip from some of you old timers that know your way around these old girls??

Thanks, Pinch

Personally I don't think your upper rad hose could get hot if the thermostat was not opening. I think you have no flow for some reason.

Always easy to find out if it is the thermostat, take it out and run it without it.

Still over heats - not the thermostat.

Is the radiator an exact match for the original? As you know the fan is very close to the radiator normally, if the replacement has more clearance (even an inch) it can have a big effect especially if the hood is open.

Will do.

New radiator very close to fan in fact I think it's a hair closer than the original.

Would love to know more about this concept of an air trap...

Pinch

Most new t-stats have either a check valve or even a small hole (bleed hole) drilled into it so a little water (and air) will pass even if the t-stat is closed.

If you drain the coolant, there is air in the block and the t-stat is closed (as the motor is 'cold'). As you fill the radiator/block the water rises, but the seal on the t-stat will not allow air to escape as the water rises. So you have an air bubble in the block. Since the motor is normally tilted up a few degrees it compounds the problem of the air bubble right at the water pump/t-stat.

If you drained 2 gallons, you should have put 2 gallons back in, otherwise there is air in the system.

That's how you get air bubbles in the system that can do what you are seeing.

The t-stat is right on the top of the motor. Drain a few qts of coolant, look at your t-stat and see if you have a check valve/hole if not, take it out and simply drill one.

T-stat with the bleed hole

Also, if you run the motor with the radiator cap off after the temp reaches 180 of so the t-stat should be open and you should be able to see the water come from the top hose. Look for bubbles and moving liquid. Its easier to tell whats going on if you don't fill the radiator all the way, that way when the t-stat open you should see coolant rush into the top tank via the water pump.

Thanks much... great info. Will do the above and see where I stand from there.

Would it make sense that the top hose is hot, bottom cold, and I get dripping from the cap when it gets up to temp - if indeed there's air?

Will post pics of the old girl when I'm finished. She's got new gas tank, new brakes through and through, POR15'd, new radiator, and is juuuust about ready to get the cab painted back to her old fire engine red. Allllllmost there, must, carry on, must com - com - compleeeeeete.

Pinch

Thanks all.... simple 1/8th inch hole in the thermostat...did the trick beautifully.

Pinch

Sounds like air trapped in the block/system to me. Try running it without the radiator cap, maybe milking the top hose a little while you do. Worked for me.