need help with VAC running hot

caseydog

Member
I have a VAC that after about 10 to 15 minutes of use the temperature gauge reads close to 200 and continues to climb. There is plenty of coolant, there is not thermostat on the tractor and the fan runs fine. When I shut it down the water in the radiator is real hot.

What should I check as to why the water heats up so fast?? I would appreciate any help as I am at a lost. I should mention I switched out the temperature gauge and probe in thinking it was misreading but the old one and the new one show the same thing.

Thanks you in advance
 
with no thermostat that water should be moving as soon as you start the tractor. If it isn't moving until the water gets hot, your water pump is shot. Or you have an obstruction in your radiator or hose. That's my best guess
 
I did not mention but in a senior moment I started the tractor with the top radiator hose off and it seemed as though I had pretty good flow all over the shop.

I am just surprised that the engine and the water in the radiator heats up that fast
 
(quoted from post at 02:56:03 05/25/18) I did not mention but in a senior moment I started the tractor with the top radiator hose off and it seemed as though I had pretty good flow all over the shop.

I am just surprised that the engine and the water in the radiator heats up that fast


The VAC t-stat mounts in the top radiator hose. If it's not in there do what kenbob said, start the engine with the radiator cap off. You should see water really moving.

Joe
 
Lots of things to check: fan belt tight? Grab the fan and turn it, does it slip or turn the motor? (Probably won't fight compression but a little bit.) Radiator plugged (draw the coolant down a bit below the tubes, look for calcium buildup)? Coolant clear and green, not rusty? Oil look good, not milky? No crimps in hoses? No chaff in the fins, nothing restricting airflow? Ignition timing good? BTW, when you say it takes 10-15 minutes to heat up, do you mean idling or working hard? 15 minutes of idling with no thermostat in the system should leave it only slightly warm.
 
I have been fighting the same problem with my dad's 1950 VAC. I have done every thing from recore radiator to remove thermostat. What I have found is that the exhaust manifold gets very hot while the front cylinder is cool. So this takes me to the cylinder sleeves are plugged ,and not letting coolant pass that is causing the over heating. Jerry from Ohio
 
Engine blocks on the DC and CC and model L...all with cast iron radiator have more problem with rust than the brass radiator tractors. I doubt a VAC would plug from deposits as any I have had apart are pretty clean. Fill the system with 2/3 vinegar and 1/3 water and run a couple hours...it will clean the inside of the radiator pretty good.
 
(quoted from post at 12:23:34 05/25/18) I have been fighting the same problem with my dad's 1950 VAC. I have done every thing from recore radiator to remove thermostat. What I have found is that the exhaust manifold gets very hot while the front cylinder is cool. So this takes me to the cylinder sleeves are plugged ,and not letting coolant pass that is causing the over heating. Jerry from Ohio

I saw that in a DC block I was rebuilding. The number four sleeve was completely encased in rust flakes and number three sleeve was getting encased about 3/4 of the way around. I removed this stuff by the hand full after I removed the sleeves. I never did explore where all this rust had come from.
 

Get a hose and wash the radiator fins out good first thing. I've seen mine plug with mud from the narrow front splashing watery mud up as I worked it. Go from front and rear. We have to do this on all out tractors every spring and usually at least once a summer to get the chaff out.
 
(quoted from post at 01:03:18 05/26/18) Is there any way to check for this without pulling the sleeves

I'm not sure if that would be the case with a VAC block. I'm wondering if the tubes in your radiator are plugged, or if the cooling fins plugged up. These issues were mentioned by other posters on this thread.
 

If nothing these gents suggest gets results, top off the radiator to the top and start it, if it bubbles or froths up maybe you have a bad head gasket.
 

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