help with grounds master 72 runs hot

[Lickity Split]

I have a grounds master 72 with a 72 inch cutting deck, I bought the machine last fall used, and have been fixing it up.
It has a R-8 continental 4 cylinder liquid cooled motor.
The problem that I am having is it likes to run hot 225 degrees.
The guy before me must have removed the thermostat, the water pump is good, pumps at all RPMs.
The radiator seems to be pretty good, not brand new but ok.
I tried to flush the radiator, but that did not help.
I think that my next step is to remove the radiator and replace it with a bigger one or something.
How do I know what size radiator is in it, and is bigger better. cooling capacity is 6 quarts stock
Is 225 to hot for this machine, not sure.
Thanks Frank

 

[J_J]

You know of course. that water boils at 212 degrees. On just about on any liquid cooled engine, if you leave the radiator cap off and let the engine run, the water will boil. The radiator is designed to pressurize the radiator, and let the engine run hotter. There is probably a formula as to pressure and degrees. You also know not to take off the radiator cap off, after the engine has been running awhile, Bad things will happen. Do you know what pressure the radiator is rated for? Is you radiator cap working right? A lot of people take out the thermostat to allow full flow with no restrictions. The thermostat is designed to allow the engine to reach proper operating temp.

A radiator cap with a higher pressure rating will let the engine heat up past 212 without boiling.

 

[Lickity Split]

Thanks JJ.
It has a 16 pound cap on it, Monday I am going to use a laser temp gauge to see if it is really running that hot.
I also will get a temp reading on the exhaust manifold to see what temp that is running at, should be around 900 degrees from what I am told.
I am thinking that the engine is running lean and is making it run hot.
If that is not it the radiator is coming out and going to the shop.
What do you think?
Thanks again
Lickity split

 

[Lickity Split]

16 pound cap is new

 

[J_J]

I believe the rule for pressure/boiling point is, for every 1 lb of pressure, the boiling point will increase 3 degrees. So with a 16 lb cap, the new boiling point would be about 260 degrees. Now you can see why, if you remove the radiator cap on a hot radiator, the water will flash to steam. I remember just one episode like that.

 

[Lickity Split]

Just checked exhaust manifold temp with laser gauge temp was about 800 full throttle under a load.
Tractor temp got up to 230 on temp gauge, and 224 with laser gauge.
Just seems kind of hot??????????????????
Remove the radiator next??????????????
Help

 

[J_J]

Here is a similar answer from WIKI.


Answer

Water normally boils at around 212 Degrees Fahrenheit at 1 atmosphere of pressure. Raise the pressure under which the water is stored and the boiling point goes up. The addition of a chemical such as Ethylene Glycol also elevates the boiling point. So the answer depends on how much pressure the system is under and if it has a 50/50 mix of Anti-Freeze and distilled water. Assuming it has a 50/50 mix in the system the boiling point will be around 223 F. Add a typical 14-15 lb/in pressure cap on the system and the boiling point goes to around 268 F. So when your radiator boils over it is HOT!

I think you are see a normal condition.

 

[Ironroad38]

you need the t stat in to hold the water in the rad long enough to cool off. and to hold the water in the block long enough to absorb the heat.

 

[Lickity Split]

Just got the radiator back from the shop, had to get it re-cord $500.00 ouch.
Put it in getting to late to try it, will post when I get it running.

 

[Lickity Split]

SHE WORKS MINT!!!!!!!!!