3A overheating problem


Bigger Hammer
Jun 1, 2016
Terre Haute, IN
First Name
Willys Model
  1. CJ
Willys Year:
  1. 1951
I have a 51 3A that is mostly stock. It has a rebuilt L-134, a new radiator from Walcks, new hoses, and a new thermostat that looks to be working. I can drive all day at 35 mph or below, but when I try to drive 40 - 45, the temp starts to rise. When I shut down hot, it blows coolant out the overflow and I must add more before the next drive.

I pretty sure the cooling system is working okay. The shroud is in good condition and looks to be placed properly. The only major part I haven't replaced is the water pump.

So I have three questions:

Could an old water pump be causing this?

Would a double or triple core radiator help?

What the heck is wrong???

Thanks for any guidance or advice.

Bill Foraker


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What does the temp get up to?

How much coolant is it blowing out? When its done blowing, can you still see some in the radiator?


Yes. After the blow, the level looks to be down about an inch from the filler neck. The problem is that when I drive the next time, the temps all run hotter, unless I add coolant.

I was doing some carb tuning Saturday and noticed some bubbling around three of the head studs. Some other guys have told me that the studs need to be sealed with permatex #2 as they are installed in the block. I'm guessing that wasn't done, so I've ordered a new head gasket, new studs and nuts, and I'll seal the studs this time. Hope that might cure a slow leak prob.



I did not put that sealer on my threads and have never had an issue. I probably have about 10k on my 15 year old rebuild. Obviously, you should not have that bubbling at the studs though. I would look to make sure they are torqued correctly too. if they are loose, that might cause the bubbling. Do you have a governor on it?

I would also check to make sure your fan belt is tight and not full of oil or grease.

Do you have an overdrive?

What speed does the needle start climbing and how hot does it get?


I know the studs are torqued okay. I just checked them a month or so ago.
No governor.
The fan belt is tight and the fan looks to be moving lots of air.
No overdrive.
The temp starts up after I'm driving 40 or over for about 5 minutes. It never seems to come back down. I don't have numbers on the gage, so I don't know what the readings are. I only have normal range and then a red line at hot. Sorry.

and Thanks for any thoughts you might have.


So its not a stock gauge. Its really hard to say without numbers. You might be just fine if the gauge is calibrated differently than the original gauge's range. Might be apples to oranges.

The cooling system could be spewing coolant until it gets to its happy level. Just because fluid is coming out, doesn't necessarily mean its bad. I've had that happen when I changed my hoses. Once it hit its level, the fluid stopped coming out. My 2A runs at about 180 tops in 90 degrees +.

I'd highly recommend getting a gauge geared towards a 3A. Walcks has a repro for $24. http://walcks4wd.com/temp-gauge-late-cj2a-cj3a-cj3b.html


This is my first Willys, so I didn't know it wasn't a stock gage. I'll get the one you suggested and install it. That will certainly give me more info about my heating issue. Will I need to change the sending unit also? I suspect so.

And I've noticed the same situation with the fluid level. After the first gush, it stabilizes about 3/4 of an inch down from the neck. It runs fine there until I drive 40 or over, and then the temps rise. I'll change the gage and then start accessing again.

I've bought a new water pump as the only major component I hadn't changed in the cooling system. Do you think I should bother changing it? The old one came off the original engine and it doesn't leak, but it's old. I don't suppose changing pumps could hurt.

Thanks again,


The gauge should have everything you need including the sending unit.

I wouldn't spend any more money on parts until you have the correct scaled gauge i.e. if your current one hits red at 170 degrees, you might not have a problem at all.