Tractor overheats when mowing. No dealer actions fix it. Any ideas?

[pmsmechanic]

Too mush flow is an old wives tale. That’s not how hear transfer works.

Ok so then why does an engine that already has problems with overheating get worse when you remove the thermostat?

 

[the old grind]

Ok so then why does an engine that already has problems with overheating get worse when you remove the thermostat?

Too hot isn't always about the whole engine. There are parts that will heat up unevenly unless designed flow is maintained. Steam-bubbling can be heard from an engine when coolant seems too cool for it to happen. Taking the TS out is sometimes a poor fix for too small a radiator or poor pump flow. ('down-gearing' or outside of design). A 'water wetter' is your friend.

A properly working thermostat is like the racer's 'washer' restrictor and so is a flow limiter to keep juice in the engine longer. Being 'wide open' at the thermostat neck doesn't provide a properly balanced flow loop through the block & heads. Much coolant goes through the pump & radiator but heads will run hot while the block can stay just 'warm'. Note that heater cores are on the engine side of the thermostat and don't get that warm with TS removed because o'all coolant temp is low.

 

[finn1]

Diesel engines typically have water passages cast into the block and heads that insure that coolant circulated through the critical areas like valve bridges and around the cylinders even when the thermostat is closed to block flow through the radiator. Think of it as a dual flow path, where a closed thermostat allows recirculating, and an open thermostat allows full flow through the radiator. Partially open thermostats allow the flow to be split.

With the thermostat removed, you never get full flow through the radiator, as there is nothing to inhibit internal recirculation.

Older Diesels often had water manifolds bolted to the side of the block. Newer designs have the manifolds integrated into the water jacket cores. cores .

 

[BigBlue1]

Probably totally off-base, but something that is quick to check on is this:

What is the engine oil level like?

I had a weird set of stuff going on with my Deere x758 diesel lawn tractor this spring when I started mowing. It was running hotter, using more fuel and occasionally showed oil pressure issues (dash idiot light flickering on) as well as seeming to be underpowered. Because of the oil pressure light I took it to the dealer to have them check things. They noticed that the oil level was slightly over the full line and apparently these small Yanmar diesels are very sensitive to oil level. Being over-full causes the crank to hit the oil and foam it up. It wasn't that much over either... I drained less than 8 oz out and lowered the level to about the 80% mark and it totally resolved the issues. The crank hitting the oil in the bottom of the engine is what was causing the engine to work harder, use more fuel and run hotter.

I had changed oil last fall before snowblowing started and it seemed to run perfectly all winter long. I guess the colder temps and less consistent nature of snowblowing vs mowing minimized the problem.

Anyway, while I've known forever that *overfilled* oil can cause a problem I'd never seen a situation where ounces mattered. Most cars and trucks can run fine with 0.5 to 1 quart more oil (no, I don't do that normally, but I've see other folks do it... I'm usually really careful). So this surprised me and I'd suspect most people wouldn't think oil slightly above the full line could cause these issues.

Rob

 

[sodamo]

Been following this thread. So today after about 3 hours mowing and I see the flashing red light I just have to wonder, “Is this catching”? Shut it down, pop the hood, gee screen sure doesn’t look clogged, barely anything there.

Yesterday, I mowed about 6 hours and noticed there was significant chaff on the grills when I parked. So I knew I would be cleaning it this morning. Backed it out of the shed and grabbed my homemade genie wand and proceeded to blow everything off, taking particular care around the oil cooler. so, yes, quite a surprise when 2.9 hours later I get the red light.

Waited a few minutes before restarting, no red light. As it was almost lunch time decided I’d head back to the shed. After lunch took a closer look. Elsewhere on TBN I have voiced my dissatisfaction that to remove the screen the FEL needs be lifted and tire turned - never an issue with either my Kioti or Case that had split screen. Someday, so will my LS.

FEL raised, tire turned, I pulled the screen. Apparently my morning cleaning served only to blow the really fine particles into the radiator itself causing the blockage I experienced. This time I made sure it was very clean.

Cut another 2.9 hours and needle never went above normal.
No more short cut cleaning radiator screen.

 

[KWentling]

So nothing from the OP since 6/16. Would be nice if he could answer some of the questions asked and provide findings from using the IR temp gun.

 

[HEC]

Probably totally off-base, but something that is quick to check on is this:

What is the engine oil level like?

I had a weird set of stuff going on with my Deere x758 diesel lawn tractor this spring when I started mowing. It was running hotter, using more fuel and occasionally showed oil pressure issues (dash idiot light flickering on) as well as seeming to be underpowered. Because of the oil pressure light I took it to the dealer to have them check things. They noticed that the oil level was slightly over the full line and apparently these small Yanmar diesels are very sensitive to oil level. Being over-full causes the crank to hit the oil and foam it up. It wasn't that much over either... I drained less than 8 oz out and lowered the level to about the 80% mark and it totally resolved the issues. The crank hitting the oil in the bottom of the engine is what was causing the engine to work harder, use more fuel and run hotter.

I had changed oil last fall before snowblowing started and it seemed to run perfectly all winter long. I guess the colder temps and less consistent nature of snowblowing vs mowing minimized the problem.

Anyway, while I've known forever that *overfilled* oil can cause a problem I'd never seen a situation where ounces mattered. Most cars and trucks can run fine with 0.5 to 1 quart more oil (no, I don't do that normally, but I've see other folks do it... I'm usually really careful). So this surprised me and I'd suspect most people wouldn't think oil slightly above the full line could cause these issues.

Rob

Thanks for that post .

 

[sixdogs]

Probably totally off-base, but something that is quick to check on is this:

What is the engine oil level like?

I had a weird set of stuff going on with my Deere x758 diesel lawn tractor this spring when I started mowing. It was running hotter, using more fuel and occasionally showed oil pressure issues (dash idiot light flickering on) as well as seeming to be underpowered. Because of the oil pressure light I took it to the dealer to have them check things. They noticed that the oil level was slightly over the full line and apparently these small Yanmar diesels are very sensitive to oil level. Being over-full causes the crank to hit the oil and foam it up. It wasn't that much over either... I drained less than 8 oz out and lowered the level to about the 80% mark and it totally resolved the issues. The crank hitting the oil in the bottom of the engine is what was causing the engine to work harder, use more fuel and run hotter.

I had changed oil last fall before snowblowing started and it seemed to run perfectly all winter long. I guess the colder temps and less consistent nature of snowblowing vs mowing minimized the problem.

Anyway, while I've known forever that *overfilled* oil can cause a problem I'd never seen a situation where ounces mattered. Most cars and trucks can run fine with 0.5 to 1 quart more oil (no, I don't do that normally, but I've see other folks do it... I'm usually really careful). So this surprised me and I'd suspect most people wouldn't think oil slightly above the full line could cause these issues.

Rob

Thanks for that post .

I also had an experience with a Yanmar engine being slightly overfull and causing low oil pressure problems. I couldn't figure it out but was confirmed by a separate gauge. After researching things I learned that Yanmars can also sensitive about being low on oil as well and causing dropping pressures and engine damage. Some Yanmar dipsticks in Deere applications can be hard to check because you have pull a hood panel off so that doesn't help things out.

 

[Cougsfan]

It has already been mentioned, but I will bet pulling the thermostat out completely will help immensely. They can be quite restrictive.

 

[Oldpath05]

The thermostat can be taken out and put in boiling water, if it opens up it's good or can put in a lower temp thermostat, if that's not the problem then its radiator or motor block plugged up. I think the only time a water pump goes bad is if starts leaking.