farmall cub, overheating

brockmahler · Jul 27, 2012

I have a 1950 cub that is completely rebuilt, including a new radiator and tank cleaned block with rebuild etc...
When I run it for 3-5 minutes the water temp. quickly runs up to 200 degrees (measured with the cap off radiator). I then get nervous and shut it down! I have a 1954 cub that was completely restored in the barn that measured the same way will hardly get to 150 degrees!

I just don"t know what else to try?

Paul Janke · Jul 27, 2012

Does it have a water pump? With a new tight engine and no water pump it may warm up quickly until it loosens up a little. Those with more knowledge will give more sure answers.

wisbaker · Jul 27, 2012

What type of oil are you using? Can you see water circulating? Does it have a thermostat? Have you checked or replaced the thermostat? Are you using a thermometer in the radiator or looking at the gauge? Has the gauge been checked or calibrated? As the other poster said sometimes when they are rebuilt they are a little tight and run hot until the parts get friendly with each other. What does the oil pressure look like when it gets hot?, does it smell hot? Have you re-torqued the head?

I guess what I'm saying is do other indicators support it being hot? I fought low oil pressure on an old AMC, finally fixed it by replacing the oil pressure sender.

Rusty wheel · Jul 27, 2012

My cub was doing the same thing. Turns out the fan would stop turning because the fan shaft and bearing was worn out. There's no good way to lubricate it. You can get a replacement for it that has a ball bearing in it if that's the problem.

Gchase24 · Jul 27, 2012

Farmall cub does not have a thermastat or a water pump. It is thermo siphon circulation. Wash your radiator fins from the back side. Make shure the fan belt is tight.

old · Jul 27, 2012

Well with the system they have you may have it a tad bit out of time which sure will make them run hot

RayP(MI) · Jul 27, 2012

Did you happen to put antifreeze in without mixing with water? Thermosyphons don't do well unless coolant is mixed.

Rollie NE PA · Jul 27, 2012

You said that it was rebuilt. Did they bore the cylinders? If so, thinner cylinder walls sometimes can cause overheating problems. Don't fill the radiator to the top. It should be filled half way up the tube that you can see with the cap off.

Anonymous-0 · Jul 27, 2012

You have either

-100% glycol in the radiator and it should be 50/50 with water

-timing is off, probably too late or else you would have trouble starting it.

-restriction in coolant flow somewhere in the system. Did anyone put a rag or towel in somewhere when they painted the rebuilt engine?)

-No or low air flow through radiator.

-also, carburetor mix may be very lean, but you should have some run problems as well.

El Toro · Jul 28, 2012

Make sure its getting plenty of fuel as that will cause it to overheat as been mentioned. An air cooled engine will overheat. That's what caused a 72 VW super beetle to ruin the engine. I bought it back in 1973 and rebuilt the engine as one piston had a hole burnt thru it. It still overheated when I got it running. I had a shop manual and all it said was not to tamper
with the carb where the red cap was installed.

I called the local VW dealer and asked them and one mechanic said pull that red cap and open that main jet to enrich the fuel mixture. That fixed the overheating on the VW. Hal

farmall cub, overheating

brockmahler

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Paul Janke

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wisbaker

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Rusty wheel

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Gchase24

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old

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RayP(MI)

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Rollie NE PA

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Anonymous-0

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El Toro

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