Diesel mower running Hot.

[GRWOil]

Two years ago my dad and I traded off an old motor home and a jeep for a 12 foot mower to take care of a new place we just moved into. It's a John deere diesel, 54 horse, that we use to mow 12 acres (below is a picture of one just like it). After tomorrow I'll be headed home from college for the winter and I'll start maintenance on all our equipment. I usually run it at wide open throttle in the summer but whenever the ambient temp was above about 80F I would get problems with it overheating. When the thermostat climbed above 230F it would start to bog down and lose power. To combat this I would stop half way (after about 2 hours) and grab an air hose to clean all the grass out of the engine bay and radiator, when in the past I would only clean it off before putting it away.

What can I do to improve the cooling? Would flushing and replacing the coolant make a difference?

 

[Chris142]

What kind of fan does it use? Is the coolant dirty how about the radiator tubes? Any cold spots on the core? thermostat getting lazy?

 

[CT8]

Originally Posted By: Chris142
What kind of fan does it use? Is the coolant dirty how about the radiator tubes? Any cold spots on the core? thermostat getting lazy?
+1 that is a serious mower !!!!

 

[The motor guy]

Does the fan work? Thermostat stuck?

 

[GRWOil]

Originally Posted By: Chris142
What kind of fan does it use? Is the coolant dirty how about the radiator tubes? Any cold spots on the core? thermostat getting lazy?


The fan is mechanical, mounted to the crank right off the back of the engine. The coolant in the reservoir looks alright, slightly murky but still greenish (don't know if it's ever been changed). I'm reasonably sure the thermostat opens up fine. It'll cool off if I stop for a minute and run the engine under no load. I couldn't tell you if there are cool spots on the radiator, maybe that's something I should check for.

 

[CT8]

How clear of debris is the radiator can you see light through the fins of the radiator?? Is there a pre radiator screen some where ?

 

[GRWOil]

Originally Posted By: CT8
How clear of debris is the radiator can you see light through the fins of the radiator?? Is there a pre radiator screen some where ?


That was the first thing I checked. I make sure it's kept reasonably clean. This mower actually has a pretty great setup to keep grass out of the radiator. There's a screen the length of the engine bay on top that it draws air through. It's pretty reasonably sealed from the bottom, keeps it clean for a long while.

Here's a picture of a mower like it that I found on the internet. (That's best I can do before I get home for the winter)

 

[clinebarger]

Check for blockage in the radiator core/cooling stack, Remove the radiator if you have to. Usually mowers like that also have a Hydraulic Cooler also that may need a good cleaning.

I know you used air to blow out the radiator......That may not be enough!

 

[fields]

I would do it all-check radiator, thermostat(I had a kubota do the same thing and it was the thermostat),and antifreeze. The cloudy antifreeze would make me worry about all of it.

 

[bioburner]

As clinebarger stated you probably will need to get to the radiator with a power washer or totally remove and flush it too. I had a sod farm and almost every piece of equipment would have to have the radiators power washed as some fine fuzz would get lodged deeper into the fins than a good blast of air could touch. Pretty sure your unit will have a sytem to cool the hydralics. Pretty important to keep up on its filtration and cooling needs.

 

[GRWOil]

Originally Posted By: fields
I would do it all-check radiator, thermostat(I had a kubota do the same thing and it was the thermostat),and antifreeze. The cloudy antifreeze would make me worry about all of it.


Had the same thing happen on my Kubota RTVs. The sensor that switches on the radiator fan, wouldn't work. Have to replace one when I get home. It actually worked out well for me, around Thanksgiving someone broke into our garage and took off with our RTV. It overheated 2 miles down the road and shut down. Alas, I don't think that's the problem here. Sounds like murky antifreeze could be a bigger deal, though.

 

[bubbatime]

I saw a video where a simple flush of the radiator with new coolant dropped the running temp by like 20 degrees. Flush the coolant out, perhaps swap the thermostat so you know you got a new one in it that works.

 

[GRWOil]

Originally Posted By: bubbatime
I saw a video where a simple flush of the radiator with new coolant dropped the running temp by like 20 degrees. Flush the coolant out, perhaps swap the thermostat so you know you got a new one in it that works.


Does anyone recommend those chemical flush products that you mix into the coolant before draining the old stuff? Or should I just drain it and stick the hose in there and wash it out?

 

[eljefino]

Chemical flushes are good if you think you have lime scale which comes from your groundwater and varies from location.

 

[dlundblad]

If its good for about halfway through the mowing job, it sounds to me like the screen/ radiator is just getting blocked with debris. I usually have to clean sometime between start and finish when the dandelions are out and have turned to seed. Towards the end of the year, not so much, but I clean the mower after every use too.

It's a little 18 horse diesel Kubota G1800.
I mow about 5 acres, plus about an hours worth of trails throughout the property.

*I've seen a turbo'd JD like this fitted with a cab and a snow blower. Looked like a pretty fun toy.

 

[edwardh1]

yes, water wash the cooler

 

[Bgallagher]

I would change out the thermostat and coolant anyways. Be sure to get the John Deere stuff. I would also give it a good flush with something citric acid based and flush with distilled water. Also check out the fins and fans for any damage.

 

[edwardh1]

do all those wheels turn freely?

 

[GRWOil]

Originally Posted By: edwardh1
do all those wheels turn freely?


The small wheels that support the decks do. Every one of them has two grease zerks. One on the bearing, one on the spindle.