Radiator Leaking and Boiling

[Posco]

Keeping the coolant under pressure raises the boiling point of the coolant. This prevents boiling as you reach the cooling capacity of the system, effectively increasing the capacity.

Hey, Jim. Are you saying there is an advantage to adding a pressurized cap? I put a new radiator in my Cub last year. I bought it from Yesterday's Tractor Co.. There was concerned voiced somewhere in here about them not mounting well. I quizzed the salesman before I bought it and he said he had zero complaints on that issue so I went ahead and ordered it. It mounted fine.

Anyway, I'm running straight distilled water in mine and find I have to top it off frequently. I've looked for leaks but can't find anything. I add maybe a quart at a time. Makes me nervous.

[Bill]

https://durathermfluids.com/pdf/techpap ... -point.pdf

[Pompiere]

Is there an upper limit to the pressure the radiator can take? If they were designed with a zero pressure cap, how much is too much? I have a 7 psi cap on the LoBoy and it vents off when I am mowing. Would a recovery reservoir like on a car work?

[Posco]

https://durathermfluids.com/pdf/techpapers/pressure-boiling-point.pdf

Not trying to pin you down but this seems to be an endorsement for a pressurized system. So, I need to plug the overflow tube and install a pressurized cap. Any recommendations on a specific cap? Model or part number would be appreciated.

[Bob McCarty]

Over pressurizing an old radiator could cause a leak. They work fine without the pressure cap. If you have a problem with boiling over, you probably need to flush the block, radiator and bolster. Otherwise, TM sells two 7 lb caps for different neck lengths. They also sell new Clancy radiators.

[Eugene]

When the engine was apart I powerwashed the bolster and block with the washer set at 800 psi to prevent any damage.

You need to clean the internal engine block coolant passages, specially around and behind # 3 and #4 cylinders and the bolster interior. That's where the crud and sediment accumulates.

In warm weather these engines run hot, any where from 190 to just below the boiling point.

[ntrenn]

Don't ever run just distilled water. You really need the corrosion inhibitors they put in today's anti freeze. Also...we in the northern climates need the antifreeze to keep our blocks from developing unwanted holes.
As far as temperatures...the nebraska tests showed a top tank temp at 205 or so. These tractors need a large delta t across the radiator so the coolant will circulate.
Rural king sells handheld laser thermometers for about $10. Check your temperatures...if you have nucleate boiling away from the radiator a pressure cap will help. If its boiling backwards through the radiator you have an outlet restriction that is causing the backflow or bad cooling at the radiator.
Also...how good is your fan drive? Can you turn the engine with the fan?
Basic operating principle....engine heats the water...it percolates out the top hose...fan cools the water like crazy....dense water falls to the bottom and feeds the percolater...repeat...

[Jim Becker]

Are you saying there is an advantage to adding a pressurized cap?

That is why everything built today has a pressure cap.

The second Nebraska test showed a top coolant temperature of 215, so plain water with a non-pressure cap would have started to boil. That temperature was only reached under a full load but was on a new tractor where everything was clean and working perfectly. The altitude in Lincoln is only about 1,000 feet. Move a tractor running plain water to Bob's place which is near a mile high and a pressure cap gets more important.

The only drawback to a pressure cap is the question of whether the old components can handle the pressure.

[Jim Becker]

Would a recovery reservoir like on a car work?

Work for what? The Cub has an adequately sized upper tank so a recovery bottle is totally pointless.

[Posco]

Don't ever run just distilled water. You really need the corrosion inhibitors they put in today's anti freeze. Also...we in the northern climates need the antifreeze to keep our blocks from developing unwanted holes.

I thought I was doing myself a favor by running the distilled water. The hard water in this area plugged the new coil I had put into my boiler for domestic hot water in just six months. I assumed it would have the same effect on the radiator passages.

I run antifreeze during the colder months. We can hit thirty below in the winter months.

[Bill]

I have 53 and a 49 cub never used a pressure cap. I posted about the effect of pressure on the boiling point. I remember driving a 1950 chevy in the mountains, if not for 4 pound cap I believe I could of had a problem.
Bill

[Glen]

Hi,

Posco, my 2nd post on page 1 of this post has listings for the 3 radiator caps that TM Tractor sells.

Good anti freeze - coolant is made to use year around. There is no need to drain it out in the Summer and use water.

[ntrenn]

Wow...you must have terribly hard water..
In that case using distilled for the water half is good.

Most modern antifreeze has corrosion inhibitors good for 5 years. I saw many cars that people ran with straight water and they all were a crudded up mess. They were too cheap to fix their water leaks and too poor to buy antifreeze..
There is a dorman overflow bottle that would be perfect for a cub...about the size of a 20 ounce coke bottle. Would stop the dribbling on the bolster..