YM2000 running hot

Brake Weight · May 28, 2011

First post.

I've had my YM2000 for several years now. I changed the water pump last year when it started to run hot, and drip at the shaft. It runs cooler than it did prior to the new pump, but it's hotter than it was originally. It holds around the 200F mark, or a needle width higher when running the finishing mower. Which isn't so bad compared to the others here that I've read.

When it starts to get up to the boiling mark(ususally involves it running a 4' tiller or 4' bush hog in high grass) I'll cruise over to the water hose. Put a few shots onto the radiator and letting it idle until it cools off.

Question is, does the YM2000 have a thermostat? When I let it idle cool, there's a noticable drop in temp and a change in the sound of the idle that corrospond. Is this a bad thermostat or just a coincidence? Also, is this a bad practice? As this is my first diesel.

winston1 · May 28, 2011

Don't believe the 2000's have a thermostat. I'm sure your exterior radiator fins are good and clean allowing good air flow? If so, your radiator might need a good flush job or tanks taken off and cleaned by a radiator shop. New radiators are high. Yanmar Tractor Parts: RADIATOR _

California · May 28, 2011

What Winston said. My YM240 had a freshly rodded-out radiator when I bought it and it has never gotten hot. Well, at least after I learned that mowing includes the necessity to flush chaff out of the radiator fins occasionally.

And there isn't a thermostat. I used to put cardboard in front of 2/3 of the radiator for light work in cold weather but I don't bother any more. In theory keeping it hot will let it run more efficiently and avoid crudding up the rings and injectors, but in practice I don't know that it makes any difference.

Ginormous · May 28, 2011

I flushed my radiator (YM1700) recently after buying it. There was a LOT of junk in there. When I re-filled, I used a 30-70 mix and added Water Wetter. I do not have a water pump on mine; it circulates by convection. It runs at around 200 under a good load.

Johnp33 · May 28, 2011

You need a clean cooling system and it should have antifreeze good to -40F to work efficiently. Cooling system must be clean internally and externally. Test it with an inferred tester, when it is hot you can test if the coolant going into the motor should be at least 20 degrees cooler than what comes into the top of the radiator.
Just a thought!

Brake Weight · May 28, 2011

Thanks. I flushed it with my water hose when I changed the water pump out. I may pull the radiator anyway to have a look. The fluid at the top of it is nice and green, and rolls around when I look at it w/out the cap on after I first crank it.

Brake Weight · May 28, 2011

Johnp33 said:
Test it with an inferred tester, when it is hot you can test if the coolant going into the motor should be at least 20 degrees cooler than what comes into the top of the radiator.
Just a thought!

I actually have one of those. I'll do it next time I run it.

clemsonfor · May 28, 2011

If there is no junk like grass or seed built up on the radiator i would say that you need to have that radiator professionally cleaned. You may have some rows that are crudded up and not working.

And i second those others, there is not thermostat

Brake Weight · May 28, 2011

I just ran it again. I made about 15-80' passes between my rows and it got hot. Gauge said it was near 220. Infared thermometer said it was 210 into radiator, and 195 out. I guess I'll be cleaning it out soon.

Ginormous · May 28, 2011

Brake Weight said:
I just ran it again. I made about 15-80' passes between my rows and it got hot. Gauge said it was near 220. Infared thermometer said it was 210 into radiator, and 195 out. I guess I'll be cleaning it out soon.

You might first try using some of the stuff they sell at autoparts stores to flush radiators.