Newby intro and YM2000 question

[woodz428]

Hello everyone I'm known as Woodsy and do a lot of tech help on several Hot Rod and Cobra sites since that is my livelihood. While I am from a Farm family most of my experience is in older American tractors.
Now the question. We bought a used Yanmar 200 last year and I've been using it for a while with no real issues. Last year I noticed the temp light would come on periodicly and attributed it to the bucket on the front restricting air flow since the engine was never hot. I figured that the sensor was weak and from some of the posts I've read that sounds likely. Yesterday while ,mowing with it I noticed that the coolant recovery bottle kept popping the lid and thought it was probably the rough terrain and kept and eye and nose on it and stopped and put it back in, this happened maybe a half dozen times in a couple hours. As I was on my final pass I heard a large POP and immediately shut it off. I discovered that the top radiator tank and "popped" from it's seam and was bowed away from the core. After closing the seam some I topped it off and brough ti t back to the shop, not gad and it still runs as good as it ever has.
I suspect a blown head gasket is the only possible reason for the radiator to grenade. There is no water in the oil. Is this a common problem? Has anyone else experienced the same? Is there something other than a head gasket that could do that on this tractor?? I've been a mechanic since the 60s and this is the very first radiator I have seen do this and so a little unsure of my diagnosis and wanted some Yanmar seasoned input. Any help/suggestions will be greatly appreciated. If it is, as I suspect, the head gasket, is there a recommended shop to purchase it from?
I also have the front wheels developing cracks from the bolt holes and am going to need to get some replacements as well. These are flat and I've noticed that some of the later ones have an extra contour in the center for what I assume is more strength. Will these work on this tractor? The tires are foam filled so will have to be replaced so a different diameter is not of concern unless it is too large to clear the bucket mounts( Koyker).
Thanks again.
Woodsy's Gearhead City

 

[normde2001]

"I suspect a blown head gasket is the only possible reason for the radiator to grenade."

Wouldn't it also require a bad radiator cap?

 

[kenmac]

I would say that a lot of pressure built up from somewhere & had to relieve. No water movement, air movement etc.

 

[woodz428]

Since the coolant recovery tank was getting water flow from the radiator as it was running , I discounted that as a possibilty...although initially it was in the thought processes. I first thought the the reservoir top kept popping off from the vibration ( it would spew the coolant when it came out), but am begining to think it was from the excess pressure in the system. I wasn't concerned about coolant loss since it doesn't draw it back into the system until the temps drop. But on reflection it seemed to be putting out a steady stream, which at some point I thought would stop after it reached temp. I inspected the cap and don't think that it is the culprit with the other events that were occurring.
Is this an unusual circumstance with this tractor?

 

[kenmac]

.
Is this an unusual circumstance with this tractor?



I would say that it is unusual for any liquid engine to do this. Given, all in the cooling system is working properly.

 

[normde2001]

"I inspected the cap and don't think that it is the culprit with the other events that were occurring."

That's why we have pressurized caps. Any pressure over 7-12 lbs, (depending on your cap), should escape through the cap and save your radiator.

 

[Dick_Jermyn]

Look at the radiator cooling fins. The unit is probably plugged up. When the unit is cool, flush the fins backwards with a mild hose spray. Does your radiator have a filter screen in front of it? Also check out the proper antifreeze/water ratio. A 50/50 ratio will sometimes cause a overheat problem. Maybe a total flush of the radiator is needed. No air flow will cause a boil over. You could have a bad radiator too. Keep us informed as to what you find.

Dick Jermyn

 

[woodz428]

The cooling tubes in the radiator look really clear, no build up of any kind. I am still leaning toward the head gasket since I can't imagine anything else that would create enough pressure to blow the seams on the top header tank. After it cooled down and I topped it off( after closing the seams some on the header tank), I looked inside the radiator again when I shut it down at the shop. It was very foamy..another reason I am focusing toward the head gasket.
Other than pulling the head, is there some way to determine if a cylinder is pressurizing the cooling system? On a gas engine I would pressurize the cylinder through the spark plug hole, but I don't have that option on the diesel. Is there a similar procedure that can be used on a diesel?

 

[normde2001]

The cooling tubes in the radiator look really clear, no build up of any kind. I am still leaning toward the head gasket since I can't imagine anything else that would create enough pressure to blow the seams on the top header tank. After it cooled down and I topped it off( after closing the seams some on the header tank), I looked inside the radiator again when I shut it down at the shop. It was very foamy..another reason I am focusing toward the head gasket.
Other than pulling the head, is there some way to determine if a cylinder is pressurizing the cooling system? On a gas engine I would pressurize the cylinder through the spark plug hole, but I don't have that option on the diesel. Is there a similar procedure that can be used on a diesel?

The radiator cannot split if the cap is releasing pressure as designed. The radiator probably won't hold pressure now that it has split, without re-soldering, but release the pressure, crank it over for a few seconds at a time, with fuel off so it won't start, and see if it builds pressure, or start it up with cap off and see if the water in the tank is bubbling while cold.

 

[kenmac]

You can buy a cooling system pressure test kit at most auto parts stores that will test the cooling system for leaks. It attatches to the rad. where the rad. cap goes.Could the rad.b stopped up on the inside ? did you check ?