Overheating Flathead

[WasabiMike]

My 49 F1 started overheating. Pulled the thermostats & tested. Made sure they were installed correct. What am I missing?

[40cpe]

Is it loosing water? I would start by warming the engine to make sure thermostats are open, fill radiator to the top, remove the water pump belt(s), run the engine and look for bubbles in the radiator neck. Bubbles will indicate leakage from the combustion chamber.

[FlatheadTed]

Leave the thermos out

[WasabiMike]

Thanks, will try. It holds water pretty good. Heats up to stall after driving a block

[Talkwrench]

What is the condition of the rest of your cooling system? when did you change coolant last , when was the last time the radiator was serviced?

[Binx]

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If this came on suddenly, be sure your distributor is working correctly. a retarded ignition will cause overheat quickly.

Lonnie

[Mike in AZ]

welcome to the 'Barn....got pics??....hope your problem gets solved with minimum fuss.....Mike

[SofaKing]

Originally Posted by WasabiMike

Thanks, will try. It holds water pretty good. Heats up to stall after driving a block

If you are saying it gets hot enough to stall in a block, the problem is not the cooling system being unable to get rid of the heat. It's more likely uncontrolled heat entering the system. 40cpe alluded to this earlier. If it was mine I would start pulling the plugs and looking to see if one or more chambers looked cleaner than the rest from being steam cleaned via water leak at head gasket. You can also use an infrared thermometer, $20 at HomeDepot, and shoot the heads to see if there is localized heating. A large temp difference will show which cylinder is the probable source. I've seen 30-50 degrees difference myself. This assumes that you have coolant, and the system is unchanged from when it was not overheating, nothing obvious, all previously mentioned.
Before I pulled it apart I'd at least try torquing the heads, always best to do the cheap and easy stuff first, IMHO.

[WasabiMike]

So, the thermostats have been in and out so many times. what the proper direction. Thermo is stamped "Radiator" direction. Toward radiator or toward block

[SofaKing]

Originally Posted by WasabiMike

So, the thermostats have been in and out so many times. what the proper direction. Thermo is stamped "Radiator" direction. Toward radiator or toward block

The side with the spring mechanism is what senses the water temp. It needs to be to on the "hot" side or towards the block.

[51 MERC-CT]

As stated, spring towards block sitting in goose neck like this.

[flatford8]

Isn't it ironic that your having a heating problem and your name is "Wasabi" Mike?.... Mark
P.S. I'm not making light of your issue and I do hope you get it solved before any damage is done.

[FlatheadTed]

Like I said leave them outttttttttttttt until you find out what's wrong with it .Ted

[40 Deluxe]

Originally Posted by WasabiMike

Thanks, will try. It holds water pretty good. Heats up to stall after driving a block

Is it puking water? Is it rumbling, boiling and making steam? Is the temp gauge pegged at "H"? Or, does it just quit running after driving a block? If so, you likely just have ignition system failure as the coil and condenser get up to normal temperature. Check for spark right after it stalls. Pull the air cleaner and look down the carb throat as you work the throttle. Should see fuel squirt from the accelerator pump. Or pull the choke as it starts to die. if it picks up momentarily, you have a fuel starvation issue.
Just my thoughts based on your stalling comment.

[WasabiMike]

So, it has a 4# radiator cap. After a driving a block, it heats up enough to spew water out of the cap thus getting coil & disttributor wet, hence engine stalling

[FlatheadTed]

The cap should not leak it should spew out the over flow pipe .replace the cap and check that the overflow pipe is clear , It could be a head gasket ,but do the other first ,Ted

[41LjH]

was talking to someone today about a Flathead overheating. The owner pickup a newly rebuilt engine and it overheated before he got home.
Turns out he did not clean out the radiator when the engine was rebuilt.

[G.M.]

Originally Posted by WasabiMike

So, it has a 4# radiator cap. After a driving a block, it heats up enough to spew water out of the cap thus getting coil & disttributor wet, hence engine stalling

" it heats up enough to spew water out the cap"?? How hot is that?
If it don't get over 210 it's not hot enough to blow out through a
4 lb pressure cap. If it's not hot and water comes out it's a
compression leak or the cap isn't working. It could be that it no
longer holds 4 lbs or the most likely case the rubber at the bottom
of the cap is NOT touching the washer like seat down in the bottom
of the filler neck. For some reason almost all 4 lb caps don't seat.
When you put the cap on line up the locking tabs and you should
be able to feel the spring pressure on the bottom seat before the
underside of the top of the cap hits the top of the filler neck. I have
to cut a red rubber washer about 1/8" thick and put it down on the
bottom seat after cleaning it good. Fill the coolant up into the filler
neck it will run cooler with more coolant. G.M.