Radiator overflow

[Poncho]

I changed my radiator and hoses, cleaned everything out and now my radiator overflows from pressure. I have the original nonpressurized cap from TM. When I run my cub with the cap on tight, it overflowed about a gallon of antifreeze in about 15 minutes. When I loosened the cap it still overflowed out but at a tolerable rate. I have been using the cub with a belly mower. Ealier this summer I changed the radiator but not the hoses, the old radiator went kaput before I had the hoses, so i just changed the radiator. Immediatetly (30 minutes) it blew out the upper radiator hose. At the time i thought it was due to an old hose, but after fixing everything I see it is building up pressure now. Did I loosen some crud up and not get it out?

Thanks to all Poncho

[Don McCombs]

Poncho,

To what level are you filling your radiator?

[bob in CT]

Did you pull off the water neck from the side of the block and flush it? A LOT of crud will build up there and cause cooling problems.
See this post: http://www.farmallcub.com/phpBB2/viewtopic.php?t=18457

[Poncho]

I am filling it below the overflow outlet and I did flush the side outlet. Once I started mowing there was a constant drip coming out causing a white mist from the fan blowing it. It was a about a gallon when I refilled it.

[Don McCombs]

If you are filling it to the overflow, you are adding too much. The Cub cooling system is a thermosyphon type. In other words, no water pump. Let the coolant find it's own level, which will be well below where you've been filling it to. You should just barely be able to see it looking down into the filler neck.

[Jackman]

Since it flows out at a tolerable rate with the cap loose I would check the overflow tube it could be plugged and causing the radiator to build pressure when the cap is tight... My overflow tube was plugged solid and I ended up making a new one with 5/16 fuel line, took time to get the right shape and then stuck it in the hole and a bit of JB Weld on the inside did the trick...

[Poncho]

The excess fluid is coming out of the overflow tubing. I thought with the cap on tight being down a gallon of antifreeze was quite excessive. With my old radiator the overflow tube was missing but the level was always visible down about an 1/2 inch from the top. Should I let him run in the driveway with the cap off for awhile to see what happens or does the cub need to be working with a load to finds it correct level?

[Jackman]

I am not expert enough to give accurate info , but with both my Cubs I always top off the radiators before I run them and they always blow some out but never more than a quart........ I top em off cause how are we to know when there over heating or low on coolant ,with out a temp gauge or recovery tank I think its best to topem off......

[RaymondDurban]

I am not expert enough to give accurate info , but with both my Cubs I always top off the radiators before I run them and they always blow some out but never more than a quart........ I top em off cause how are we to know when there over heating or low on coolant ,with out a temp gauge or recovery tank I think its best to topem off......

Unless you are using distilled water, you are adding impurities to your cooling system everytime you 'top off'. These impurities will gradually solidify and deposit themselves to the walls of the water jackets in the motor, bolster and radiator. This will surely lead to cooling problems in the long run. I would not do this unless you just like cleaning out your system every year.

[Poncho]

My cub was definitely overheating. My cause is to find out what is causing the pressure buildup with the cap on.

[RaymondDurban]

Take an air source and blow down through the overflow tube to make sure its open and clear. Remove the cap and run the tractor. Look into the radiator filler neck and look for bubbles. You may have a blown headgasket/craked head.

[Poncho]

The overflow tube is brand new and was clean, thats where the antifreeze is coming out, I will have to check for bubbles. Does it need to run very long to produce bubbles if it is going to?

[Clark Thompson]

I would say that a gallon of coolent blowing out is quite excessive. even if you did over fill the system it should only loose / blow out about a quart or less before it finds the proper level. The cause to your problem probabley isnt the cap or overflow being clogged. I would say that when you flushed the system you probabley loosened up a bunch of crud clogging up water jacket ports in the cylinder head or block or both.Since you said that it blew the hose out It is also possible & mostlikely that the headgasket had deterioated to the point that under the compression stroke it is pumping compression into the cooling system. That would also indicate the the overflow tube is plugged. I have seen headgaskets corode and do just that. I have also seen the water jackets in the block completley clogged with sludge. I also have seen tiny holes in a cylinder wall causing your problem. I would sudjest somehow putting a preasure guage inplace of the radiator cap. If it builds any type of preasure then your looking a a bad headgasket. Just a thought, has it overheated in the recent past? also check the temperature of the coolent when it starts to blow out. I use a oven probe type thermometer. If the coolent isnt overheated but still blowing out then you can be shure that there is a compression leak somewhere in the system.

[Poncho]

It hasn't overheated in the past 2 years since I have had him. The old radiator has always leaked, so maybe there may have been pressure in the system. I will check the temperature when I get home from work. Thanks all

[Poncho]

I was able to let him run for 15 minutes the last 10 with the cap on and the mower engaged. No overflow. It did produce steam though immediately after I started which I presume is somewhat normal. So I thought I would mow. I had time to mow for 15 minutes with the cap on and I had no overflow, could of there been a vapor lock of some type. There were no bubbles coming out of the antifreeze at anytime during the 30 minutes (good thing?) When I mowed the other day overflow was coming out almost immediately and I was only able to mow for 10 minutes. My wife was working today and I could not find the temp probe. What temperature should it be?

My cap and radiator are both new. The radiator seems to flow fluid ok as I am able drain and fill it.