B7800 with 600 hours over heating.

[PoTreeBoy]

Did you ever check the belt?

 

[MAXA]

He let borrow his tractor this morning before it got to hot.

I power washed the radiator again as it still looked dirty not a lot came out it was mostly grass. Then i used air to blow it out and dry it.

I took apart the air duct that feeds the air filter and it had a nest inside it of grass so no air flow. I used it for about 30min and it did not over heat.

The top radiator hose was 200F the bottom 190F or slightly less.

 

[MAXA]

Did you ever check the belt?

belt looks very worn, how hard is it to replace? I looked it up and the belt has been discontinued.

 

[Runs With Scissors]

If the thermostat isn't terribly hard to get to, I would run it without a T-stat as a test, instead of......

 

[PoTreeBoy]

belt looks very worn, how hard is it to replace? I looked it up and the belt has been discontinued.

Shouldn't be hard. That's probably a B section belt. Take it off and to Tractor Supply, supply store, etc. and have them match it. It's nothing special.

BTW, after a few hours, you may well need to tighten it again.

 

[Russell King]

.

The top radiator hose was 200F the bottom 190F or slightly less.

There should be much more of a temperature drop. I think it should be around 80 to 100 degrees F top to bottom.

 

[MAXA]

There should be much more of a temperature drop. I think it should be around 80 to 100 degrees F top to bottom.

I'll check again at some point.

 

[Jim L.]

Russell is right. Next time measure top of radiator and bottom of radiator.

Concerning belt; Go to kubotausa on internet, sub directory parts. Put in model type and mower type, then look at fan belt number. If discontinued, there will be aftermarket belts that work. Take the belt number and look it up at Messick's web site. They will show alternatives to factory. Amazon is a source if you use them.

Runs with Scissors tells what I would do to troubleshoot: take the thermostat out of the equation.

It may be worth a try to do a system flush, then run water to clean that out, take the temps with just the water to see if any improvement.

 

[MAXA]

Russell is right. Next time measure top of radiator and bottom of radiator.

Concerning belt; Go to kubotausa on internet, sub directory parts. Put in model type and mower type, then look at fan belt number. If discontinued, there will be aftermarket belts that work. Take the belt number and look it up at Messick's web site. They will show alternatives to factory. Amazon is a source if you use them.

Runs with Scissors tells what I would do to troubleshoot: take the thermostat out of the equation.

It may be worth a try to do a system flush, then run water to clean that out, take the temps with just the water to see if any improvement.

I checked on the top and bottom hoses coming out of the radiator.

Last time i used it would over heat in 10 min when in use.

The coolant coming out looked new. Dealer might have changed it he does not remember.

 

[GeoHorn]

The REASON to check if coolant is actually Moving….is to confirm the thermostat actually opened up… AND that the water pump is actually PUMPing coolant. If either of those aren’t…then that has to be resolved.

The thermostats on tractors are not usually rated as hot as autos. Auto thermostats commonly are above 190F… tractors and machinery usually lower than that.

If coolant is NOT moving when the engine is “up to operating temp”…. then either the thermostat is failed-closed…OR…the water pump has failed. (Pumps usually fail and indicate the failure by leaking at the shaft…BUT…they can also fail by the impeller disintegrating…Or the impeller SLIPPING on the SHAFT….despite the pulley being turned by the V-belt. (I had this happen and it almost drove me nuts before I realized the impeller was slipping. Changed the pump and all was fine thereafter. I could spin the shaft by hand and hold the impeller stationary with the other hand.… a rare, but possible type of pump failure.)

 

[GeoHorn]

So just run it with the radiator cap off and see if the coolant is moving? Sounds easy but i bet it's hard to tell if it's moving.

No..it’s quite easy. Use a flashlight down the open cap-spout and if the thermstat is Open and the pump is working….it’ll look like a Texas Flash Flood.

 

[TheOldHokie]

I checked on the top and bottom hoses coming out of the radiator.

r to a radiator shop a time i used it would nd have over heat in 10 e oatadithe rktamin when in use.

The coolant coming out looked new. Dealer might have changed it he does not remember.

Is this actually boiling over in ten minutes or is the gauge going to hot without a boil over?

If no boil over test and replace gauge and sender as per WSM

If its boiling in ten minutes its not circulating coolant. In this order

1. Visually confirm water pump pulley is turning
2. Pressure test cap and radiator
3. As suggested completly remove the thermostat.
4. Take the radiator out and have it flow tested and professionally cleaned.
5. Remove and inspect water pump. Replace if defective.

Dan

 

[#40Fan]

I could see the nest in the intake tube causing it to overheat. Not enough air will cause high EGT.

 

[TheOldHokie]

I could see the nest in the intake tube causing it to overheat. Not enough air will cause high EGT.

Thsts an interesting thought. You saw a nest somewhere in this thread?

Dan

 

[Trash Panda]

Thsts an interesting thought. You saw a nest somewhere in this thread?

Dan

Post #22

 

[TheOldHokie]

Post #22

Thanks!!! So this was resolved 13 posts back

 

[Trash Panda]

Thanks!!! So this was resolved 13 posts back

Apparently not.

 

[TheOldHokie]

Apparently not.

Arrrrg!!!!

Dan

 

[MAXA]

Arrrrg!!!!

Dan

HA i think it's solved time will tell.

 

[DaveFromMi]

Key point. If rad inlet hose is hot, check the air temp coming out of the fan (watch fingers). If there is a "goodly" amount of heat coming out, the coolant is flowing properly. If no heat out of back of fan with rad inlet hose hot, then there is low or no flow.