Newby intro and YM2000 question

woodz428 · May 21, 2007

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 · May 21, 2007

"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 · May 21, 2007

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

woodz428 · May 21, 2007

normde2001 Wouldn't it also require a bad radiator cap?[/QUOTE said:
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 · May 21, 2007

.
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 · May 22, 2007

"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 · May 22, 2007

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 · May 22, 2007

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 · May 22, 2007

woodz428 said:
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 · May 22, 2007

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 ?

woodz428 · May 22, 2007

Well a little update. Since most posts didn't indicate it to be a common problem and the radiator needed repaired anyway ( wouldn't hold pressure is an understatement, both the front and rear seam on the upper tank blew and the tank bulged outward) I removed it and inspected it as I repaired it. Although the guard in front of the radiator was clean, the fins in the radiator were easily 2/3 or more full of mud/fine grass and who knows what else. It took easily 30 minutes to completely clear them. After clearing the fins, and straightening a few, I repaired the tank and re-soldered it and pressure tested it..held fine. I now believe what happened was that the radiator couldn't dissipate enough heat while I was mowing for the extended period and the coolant got hotter and hotter, eventually turning to steam. The steam was releasing into the recovery tank with such force it kept blowing the top loose. After a certain point the steam couldn't release fast enough through the overflow tube as the heat built up and created enough pressure to blow the seams apart. It's repaired now and the paint is drying, I'll install it tomorrow and give it a test, but am pretty sure that was the problem. I'll post tomorrow with the results. Thanks for all the input, I was afraid that head gasket failure was a common issue...much like some of the V6 Ford engines.
Now.. what about the front wheels??

normde2001 · May 22, 2007

Sure sounds like you got the problem taken care of.

oliver28472 · May 23, 2007

If your tractor is 4WD you will need to keep the same size front tire. Lots of discussions about this. Welcome to TBN. We have a Superformance dealer close by us in NC.

Dick_Jermyn · May 24, 2007

Good to hear that hopefully you have solved your problem. Make sure that your anti-freeze/water ratio is correct. A mixture ratio of anti-freeze must not exceed 40% to aviod overheating.

I would flush your radiatior several times to insure that it is really clean.

Dick Jermyn

woodz428 · May 29, 2007

A final update, and another thanks for the input. After repairing the radiator, as I was prepping the coolant recovery for re-attachment, I noticed that the passage had melted shut from all the steam that was being produced. I drilled the hole clear again, re-installed the radiator and coolant and did a test run to check for any leaks...it was good. I then took it out and finished mowing the back acreage and it worked great with no indication of a heating problem. After running it shut down fine and a check of both the coolant and oil showed all was apparently fine. So... with all the debris in the radiator cooling fins it was creating a bunch of steam and after a while it caused the passages in the overflow cap to close up and then the pressure built up enough to POP the radiator at the header seam..I still can't believe that the pressure didn't blow the hose off the radiator to the recovery tank first, but it didn't. All seems to be great again, I will be keeping and eye on it as I start working it again.

oliver28472 said:
We have a Superformance dealer close by us in NC.

The Olthoffs, great bunch of guys, I have talked with Dennis several times and gave some assistance a couple years ago when he broke an axle running at IRP during the One Lap of America. They couldn't be too far away since their address is also Mt.Ulla.....it couldn't be spread out that far

oliver28472 · May 30, 2007

Mt. Ulla is one of those places that would not have a post office if politicians would step aside. (a very good place to live though) Dennis and family go to church where we do. His place is about 2 miles from me. The cars are test driven by my house and I like it!