Kubota M4500 Overheating

[grantwy]

Hello all,

About a year ago, I bought an old Kubota M4500. Didn't take long to figure out it has overheating issues.

I was suspecting it was the head gasket, so this spring I pulled the head, had it resurfaced, and replaced the head gasket. I found 4 of the injectors were not sealing well, so I had them rebuilt. I also flushed the radiator, and checked the water pump. But it still overheats.

Any thoughts on what would be causing it to overheat? I was thinking the injection timing could be out, but I don't have a timing light setup for a Diesel. Also not sure how it would have got out considering it is set by shims.

Any thoughts on things to check are appreciated! Thanks in advance.

Grant

 

[Kubota Newbie]

Radiator! Replaced mine last summer. Huge difference. I guess I should ask under what conditions it's overheating first and is it actually boiling over or just running in the hot range of the gauge?
Tired radiator cap can be at fault too.
My M4500 would run a little bit hot mowing hay (New Idea 272 Cutditioner flail mower conditioner) but never really boiled over.
It had a little accident last summer and I had to tear the front end apart. Radiator looked ok and seemed to pass water ok. But anywhere you touched it the fins just crumbled so it got replaced while things were apart.
Runs noticably lower temperature under heavy load now. The old 272 will really work a tractor in heavy first cutting hay.

 

[Russell King]

Is there any screen in front of the radiator? If so, is it clean?

Did you clean the radiator exterior surfaces, fins especially?

If it has been used for mowing I would recommend that you take the radiator out of the tractor and either clean it well or take it to a radiator repair shop if you can find one in your area.

 

[007kubotaguy]

Tell us more details. When does it overheat? How long does it take to overheat? What are you doing when it overheats? What is the temperature outside when it overheats? Years ago I worked with these tractors having overheating issues. Be sure you have a radiator shroud around the fan. Be sure the foam rubber is in place between the hood and the radiator.

 

[grantwy]

Radiator! Replaced mine last summer. Huge difference. I guess I should ask under what conditions it's overheating first and is it actually boiling over or just running in the hot range of the gauge?
Tired radiator cap can be at fault too.
My M4500 would run a little bit hot mowing hay (New Idea 272 Cutditioner flail mower conditioner) but never really boiled over.
It had a little accident last summer and I had to tear the front end apart. Radiator looked ok and seemed to pass water ok. But anywhere you touched it the fins just crumbled so it got replaced while things were apart.
Runs noticably lower temperature under heavy load now. The old 272 will really work a tractor in heavy first cutting hay.

Ya, I know it might just be time for a new radiator. I tried a really good flush, and soaking with CLR, but it may just be time. I wish there was an easy way of checking the tubes for blockages. It looks clean looking down the holes, but no way to know for sure...

Is there any screen in front of the radiator? If so, is it clean?

Did you clean the radiator exterior surfaces, fins especially?

If it has been used for mowing I would recommend that you take the radiator out of the tractor and either clean it well or take it to a radiator repair shop if you can find one in your area.

Yes, the screen and the fins are clean. Not brand new, but clean and you can see through easily.

Tell us more details. When does it overheat? How long does it take to overheat? What are you doing when it overheats? What is the temperature outside when it overheats? Years ago I worked with these tractors having overheating issues. Be sure you have a radiator shroud around the fan. Be sure the foam rubber is in place between the hood and the radiator.

Overheats pretty much whenever you use it. Evening before last I got about 30min of running doing some light mowing before it was into the hot. It is hot out now (30C/85F), but I was having issues when cooler too. Fan shroud is there, but there is nothing between it and the hood. I don't see any evidence of there ever being any rubber there.

Ya, the thing that seems odd to me is that you feel a fair bit of heat coming off the radiator. Seems to me that it should be enough to keep it cool, but it just keeps heating up anyways. Even if I rev it 1500rpm in neutral it really just barely moves downward. Just seems to me there is something else wrong, but maybe it's just time for a new rad core.

Thanks,
Grant

 

[Kubota Newbie]

Does it actually boil over or just show hot on the gauge?
If it doesn't actually boil coolant it could just be the gauge.

 

[GeoHorn]

Flow-checking a radiator is a simple job if it’s removed from the tractor. If the fins are in good shape and no blockage….any overheating has to be another issue.

Here’s what happened to me: My JD compactor was overheating and the radiatior, thermostat, etc all checked just fine. But when “hot’ ….with the cap removed…not a torrent of movement of the coolant.

I suspected a failed impeller on the pump. I pulle the pump….and sure enough…the impeller would spin on the shaft….(or rather, the shaft could be spun and the impeller would barely spin).

and on some types of pumps the impeller can be corroded-away…. no longer capable of pushing fluid.

I installed a new pump. Problem solved.