Overheat

I'm a new owner of my grandfathers '41 9n. It has been sitting for 6 years, supposedly ran fine. It runs great , but after about 20 minutes it starts steaming and soon is boiling over. I flushed out the system, pulled the water pump, all looks fine( never have seen a forward blowing radiator fan before). I've read posts about it could be a leaky head gasket, but it takes so long to start boiling, any ideas? Thanks for your help

It could be a stuck thermostat. Take out the old one and run without it for a bit. If it solves the overheating, put in a new one. Pay attention to which way the old one was in when you take it apart. It may have been installed backwards.

It also may be just over-filled.
They shouldn't be filled to the top like a car.
Normal level is above the visible fins, but not full.

Check out tip # 24 at the link below.
75 Tips

When I pulled water pump, couldn't find any sign of a t-stat in the hoses. The overfilling doesn't fit either because it steams until it's down a gallon or so.

It's keeps on boiling until it's pretty empty (at least a gallon

The water keeps boiling until a gallon or more low. The pump looks strang, almost like its spiking backward. The impeller curve is away from the direction it spins

donohioSeveral years ago there were some replacement water pumps that got out that had the wrong impeller on them.Check the one you have with another pump to make sure it has the right impeller on it.

(quoted from post at 21:20:09 05/25/15) The water keeps boiling until a gallon or more low. The pump looks strang, almost like its spiking backward. The impeller curve is away from the direction it spins

Click to expand...

t is supposed to "flow", NOT "dig".

If you are confident it isn't overheating from the usual causes, then you just have to bite the bullet & flush out the block & radiator. (Do NOT yank the head off. ) To flush it out, remove the t-stat from the top hose. Then, remove the bottom hose from the radiator, stuff a rag in the bottom radiator hose connection, & stick your garden hose in the top of the radiator. Turn the water on (reverse flush) & the water will flow into the radiator, then the block & out of the disconnected lower hose. Let it run until the water is clear. Then, check the radiator flow. Stick the hose in the top of the radiator; the water should flow out of the bottom w/o backing up in the filler neck. It should flow at 19.5 gallons a minute. As a final flush, put a gallon of white vinegar & about 2 gallons of water in the radiator, run it to operating temp & then drain it again.

Don’t forget to put the t-stat back in correctly!

Use 50/50 anti-freeze & distilled water as your coolant. The anti-freeze contains rust inhibitors, pump lubricant & raises the boiling point of the coolant.

If you do need to get the radiator re-cored, make sure you get the flat fin industrial core. Automotive style cores will clog up w/ debris very quickly.
75 Tips

Just to be clear--a missing thermostat will NOT cause overheating. It's certainly a good idea to have one, as the engine is happier running at normal temperature, and the t-stat helps it get there sooner.

A blocked t-stat or one installed backwards can lead to overheating, though.


I never figured out my overheating problems. But they seem to have gone away after I replaced the radiator (which received damage from other causes after the overheat problems started--I wasn't just throwing parts at the problem). It still seems odd to me, as it wasn't an old radiator, but I'm not complaining about the results...

-Paul

Thanks for the help everyone. As the picture shows, I
found my overheating problem. Probably 90% of the
tubes were at least partially blocked with rubber bits.
I cut a couple accesses in the top plate and
vacuumed out most of it and rodded all the tubes..
much cooler now! (Couldn't see anything down the
neck those were all clear) Thanks again

Thanks for the help everyone. As the picture shows, I
found my overheating problem. Probably 90% of the
tubes were at least partially blocked with rubber bits.
I cut a couple accesses in the top plate and
vacuumed out most of it and rodded all the tubes..
much cooler now! (Couldn't see anything down the
neck those were all clear) Thanks again!