switching from thermo-siphon system to water pump

I won't encourage you to go with the pump and no thermostat. Unless you plan to work this girl REALLY hard every time you start her up, she'll never get up to a good operating temperature.

When they made these engines, one option on the tractor was the radiator shutter. It was sold most to the folks with distillate-burning engines. Distillate burns cooler than gasoline, and the shutters were there to impede the flow of air and thus hinder the efficiency of the radiator so the engine could get up to temp and stay there.

Up in my neighborhood, it's not unusual to find those same shutters on gas-only tractors. I've been out moving snow uphill with mine in the bitter cold behind a storm and had a hard time getting and keeping her up to temp with the shutters open.

The thermosiphon and the radiator made for it are that efficient, even in warmer air.

My advice is that you check out your timing before going to the trouble and expense of adding a pump.

(And don't fret about the typing. A lot of folks think I can't spell. I can, and very well, thank you. But I am a lousy typist. I won't tell you the time I spend cleaning up my posts before I push the button, and still the typos get through!)

F-Dean points out my mistake in assuming (always a dangerous thing -- mea culpa) what kind of tractor we're talking about. My listing of parts changes applies only if you have an A, B, BN, or an early C. If older than an A, please disregard and we'll hope somebody with knowledge of the older tractors will chime in.

JimN is spot on about the weaknesses that can be revealed when putting pneumatic pressure on a radiator that isn't designed to hold it, and if you do decide to go ahead, I'd recommend adding a pressure rated radiator to the parts list.

Chadd is also spot on, and his further explanation of the thermosiphon is a good one, worth saving if you're into that. What jumps out there for me is his emphasis on the need for the system being clean to work properly. Is your system actually overheating or are you just thinking you want it to run cooler? It makes a difference. And his final point about running too cool is worth noting. You can sieze an engine running too hot, but it will die an early death running too cool, as well, just not as dramatic.

To Ron's point, I think Hugh and I agree that these 113s (assuming again that's what we're talking about) were built with more than adequate radiator to handle a hot load for some time. On my BN, I judge how hot she's running by how high I can put my hand on the radiator before it's uncomfortable, and that has always been above 1/3 up from the bottom, which says that the combination of tube volume and fin surface and flow are sufficient for the original sytem to do its job under all but abusive conditions.

Hugh may have misunderstood some part of my argument, because I agree with him in thinking that a pump and thermostat are not necessary.

If, after all this advice and any other you've gotten, you want to go ahead with it, I'll be glad help where I can. If you want to stay with what you've got but perhaps flush the system to try to clean it out and see if you can get your thermosiphon to work better, I'll speak up with the other folks that have ideas about the best way to do that without a complete teardown.

Let us know. We're all pullin' for ya, but we're all gropin' just a little bit, too.

Truth is Dennis hasn't given us enough detail backing up his belief that the tractor should be changed. Couple that with the fact he hasn't bothered to come back and tell us which model and if that model is presurized or non presurized.

My point was purely to emphasize, many of these tractors have been changed to pump cooling when in fact it was completely unnecessary. Dennis pointed out his goal was to make his tractor run cooler. It could be that a water pump with thermostat will actually run hotter than a good working thermosyphon. I guess we should ask him why he thinks the thermosyphon is running too hot.

Every day here at YT, I read a lot more discussion than I actually take part in, and almost daily I see folks making completely unnecessary changes to their tractors. Some of these changes are much more expensive than good maintainence to the current system. The end result, quite often sickens the participant on old tractor hobby, yard use or for what ever reason he chose an old tractor for in the beginning. I hate to see these type situations develop, often times folks will give up on the old tractor, purely the result of dumping too much money into the project. And almost as often big money could have been avoided. I've got one in my e mail right now, the guy has spent a substancial amount of money on his tractor, and I know he is going to throw in the towell, mainly because he didn't go into enough detail in his consultation here at YT. We get so many folks here at YT, afraid to post a long post, I guess for fear it might get boring. Sometimes it just requires that many words to describe the situation. We just need to find a way to get all the details on a problem. I know details are often boring, but that doesn't make them unnecessary.

The tractor I'm most familiar with is the Farmall Super A. My Super A is 57 years old and the complete system is still intact with all the same components it came from the factory with, excepting the head gasket, it was replaced in 1994. A great many of these have been changed to water pump as a result of an operator working the tractor for several hours, shutting it of immediately and hot. Then they hear the cooling system bubbling and gurgling, and think the tractor had been operating much too hot. My tractor, if shut off hot will do that today, and it also did it 57 years ago, as did every one of them when new.

If one allows my tractor to idle for 2-3 min after a hard days work, they will never hear a bubble or gurgle from the cooling system when shutt off. They were all that way when new, and a great many of them still operate that way today. Truth is most of these old tractors, thermosyphon or water pump, require that cool down period after a days work. Most folks who have lived most of their lives with pickups and cars, will say, "We never did that back then nor do we do it today, WHY." On the contrary most cars and pickups do get cooling as the last mile or so of most trips is at 30 mph or there abouts.

If your hearing what I describe, don't be hasty about changing to water pump. If your seeing steam being expelled during operation, there is a strong chance the head gasket is bad, head is cracked, or in other words a leak in the system. Just be sure your not trying to cure a leak with a water pump, it wont work.

Pump with pulley and gasket
Longer fan belt to drive the pump
Thermostat and retainer clip
Generator bracket arm

You *may* also need a different outlet elbow and a new gasket at the head. I don't know whether the one on the thermosiphons has a recess for the stat or the slots to catch the retainer clip that holds it in place. Those made for a thermostat also are usually tapped for a temp gauge sensor.

You might also need a longer stud or a bolt to replace the one on front of the block where your current generator arm now anchors, and maybe a couple of longer bolts, as the pump is thicker than the regular inlet to the engine. Basically, you lose the stud to mounting the pump, thus the need for a new generator bracket. With the pump on, the bracket is flat and shorter but has a hard to describe bend to it (flat, but the edges and the track for the slot for the bolt have a rounded elbow out near the middle, maybe 75*) that gives you some geometry to work with in tensioning the generator belt. It mounts to the outside bolt holding the pump to the block.

Last thought is I don't know whether your conversion would require a pressure cap for the radiator. Get one but only if the radiator will take the pressure.

Hope this helps.

That said, I'm curious, though. There's been a few threads lately asking about making the changes you talk about. If yours was one of them and I'm rehashing, I apologize.

My thinking is that about all you gain is heating your cold engine up faster while the thermostat is closed.

I recall as a kid being at the house when our little BN was out cultivating and unlike when I was on the tractor, all you heard at the house was the fan shouting, not the exhaust. I don't know how much of the engine's HP those fans eat up but they move a lot of air. When I first rebuilt the BN last year, I left the grille and hood off for a time while I worked her some. I didn't stick a thermometer in it , but I was satisfied tht the engine was up to a good running temp. I couldn't rest my hand on the top of the radiator when she got armed up, but it was no problem holding it against the bottom. The thermosiphon is a pretty efficient system, and if your block, head and radiator are all clean inside, you can see the coolant flow pretty well. Putting a pump but no thermostat in will only make the circulation faster, meaning it will take long hard run to ever warm you engine up to a good working temperature.

To my mind, adding a thermostat will actually make your engine run hotter. It's job is to hold the coolant in the engine, heating up, before releasing it. Did you ever have a thermostat go bad (stick open) in a car or pickup in the winter. The first sign is often that you can't get enough heat out of the coolant to warm the heater coil sufficiently, and your engine is running cooler than intended, because the pump is circulating and cooling the cooland faster than the engine can heat it up. So in that sense, yes, it maskes the engine run cooler, BUT in the absence of a thermostat that will close.

The other thought is that a pump and thermostat are also usually accompanied by a pressure cap. This is a further indication that the engine will run hotter, in that the purpose of a pressure cap is to allow the coolant to exceed its free-air boiling point without actually boiling. The thermosiphons were vented at the radiator neck below the cap.

Bottom line, my belief is that a water pump with thermostat will make your engine run warmer that it already is. A water pump with no thermostat will make it run cooler than the thermosiphon (up to a point) but would rarely allow the engine to get up to its proper running temp.

Again, I apologize if this is repetitive, and for the ungodly length. It does make a good project. I only question whether it will accomplish what you want it to.

Good luck and happy wrenching!

Free convection cooling (also called thermosiphon cooling) can be a very effective cooling system if well maintained. There are only three failings when compared with a forced convection system. One is that it doesn't work in the absence of gravity (not exactly a problem for a Farmall A), it requires more cooling area than a comparable pressure cooling system, and it must remain clean. A thermosiphon system relies on the relatively small change in density of a fluid with temperature. As a fluid's temperature increases, it's density decreases and it tends to rise. In a thermosiphon system, this creates a flow of coolant that continually exchanges the heated fluid with cold fluid. However, if there are scale deposits in the coolant passages, it causes a double-hit to cooling capacity. This is because scale causes a frictional loss that slows the flow rate of the coolant, and it also reduces heat transfer to the coolant, leading to less of a temperature differential and a slower flow rate of coolant. Forced convection will simply improve heat transfer because it pumps the water at a much faster flow rate.

On a side note, colder for engines is not always better. . . As long as it is in the run area of the gauge, I wouldn't worry about making it run colder.