Tractor Overheating

[threeoaks]

Kubota L2800 is running hot and won't cool off.

Cleaned radiator with shop air.

Fan belt is tight.

Replaced water pump.

Replaced thermostat.

Drained the radiator.

Refilled with coolant and distilled water.

Made sure radiator fluid was topped off.

Then ran the tractor and it started heating up again so I stopped.

Checked the oil and it is not milky and it is clean.

What should my next troubleshooting steps be?

Tractor has 450hrs on it.

 

[BigG]

I know you said a new thermostat. Did you test it before you installed it? A slim chance but a chance it is defective. Are the hoses in good shape. They may look good on the outside but they could collapse and restrict the flow.

 

[200mph]

Thermostat in backwards?.. It's been know to happen.

 

[RCW]

Three things come to mind.
1. See if you can see bubbles in the top link the radiator when it’s running. Means there’s a possible head or head gasket problem. There’s a fellow dealing with a similar issue here now.
2. Make sure the radiator is really clean. Some here just pull it out and clean outside of the tractor.
3. Make sure it’s really getting hot. Many of us use an infrared thermometer to check the temperature of the top and bottom radiator hoses. My BX once pegged the temperature gauge within 10 minutes. It really wasn’t even to operating temperature. Connection to the sending unit was corroded. A little dielectric grease did wonders. Just thinking maybe there’s a bad connection, sending unit, or gauge....


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[threeoaks]

Should I use a degreaser and a hose to spray the radiator?

The tractor is truly getting hot the overflow tank is bubbling and liquid is coming out of the drain tube from the overflow tank if you run it long enough.

Should I run the tractor with the radiator cap off to see if bubbles are present?

 

[Blondie70]

Overflow tank bubbling ??? Sounds like combustion gas may be in the cooling system.
If it's not that, pull the t stat completely out and try running.
If it still gets hot, leave t stat out, pull the radiator and have it rodded out if possible or checked for full flow.
Good Luck...but those bubbles are not good.

 

[Russell King]

You should start out cold without the cap on the radiator to see if there are bubbles in the fluid inside the radiator.

After it warms up then the fluid will start to move inside the radiator but you may be able to see the bubbles between cycles of the thermostat.

Have you replaced the cap with a new one or tested the existing one for pressure holding capacity?

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[RCW]

I'm with Russell. Run it cold without a radiator cap.

Try that before a bunch of other stuff. Radiator and thermostat may not be an issue now, but might have caused the problem. Don't forget about them. I would suspect the radiator first. Some guys like different household cleaners for them.

Do you see any smoke, and if so what color? Are you having to add coolant?

There's another overheating thread going last couple days. I suggest you check there also.

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[BruceP]

Lets assume you need to do more thorough checks of your head-gasket.

There is a simple "test" to check if there are combustion-gasses in the antifreeze. Since you recently serviced the entire cooling-system including fresh antifreeze, there should be absolutely none.

There is another test called "leakdown test" which replaces the radiator-cap with a hand-pump and a pressure gauge. You simply pump it up and let it sit overnight to ensure the system does not lose pressure.

Many autoparts stores will loan either of these testers so you can do the testing yourself.

Some other things you can check. These checks look for antifreeze which leaks past the head-gasket into combustion chamber AFTER you turn off the engine as it cools.
*) Is the engine harder to start than it used to be?
*) Is there a puff of white smoke (steam) when the engine is first started?

 

[jakemaxwell806]

I'm with Russell. Run it cold without a radiator cap.

Try that before a bunch of other stuff. Radiator and thermostat may not be an issue now, but might have caused the problem. Don't forget about them. I would suspect the radiator first. Some guys like different household cleaners for them.

Do you see any smoke, and if so what color? Are you having to add coolant?

There's another overheating thread going last couple days. I suggest you check there also.

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Watch for bubbles in your radiator I run mine a long time with the cap loose before I pulled the head the head gasket had a small leak letting compression in to the coolant system

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[Silver Wings]

Another easy way to identify exhaust gases pushing into the cooling system is to look for exhaust residue inside the radiator and or recovery tank. Wipe a finger inside the top of the radiator, if it come back black...that's bad news.

 

[mikester]

3. Make sure it’s really getting hot. Many of us use an infrared thermometer to check the temperature of the top and bottom radiator hoses.

Also check and compare the operating temperatures each of the vertical radiator tubes. If several tubes are blocked you will get overheating problems too.

 

[rentthis]

The first thing I would do is to really really double check the cleanliness of the radiator. Those radiators are designed small enough to require all or most of its surface to operate properly. Buildup around the sides can cause overheating. If in doubt, remove the radiator if necessary to get a good look. 450 hours doesn't seem like enough time for much more to be wrong.

 

[RCW]

Mikester and rentthis are correct and know better than me.

I would not rule out the radiator at all for causing the overheating. I’m just wondering if an overheat caused by the radiator also caused a head problem, if that makes sense.

Even if the radiator is bubbling, I would start with a thorough examination and cleaning of the radiator first followed by dealing with the head, of necessary.

I don’t think my previous post was very clear. My apologies.


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[threeoaks]

Took the radiator out and cleanded it with a degreaser and washed it off.

Ran a radiator flush cycle through.

Added colant and ran the tractor. Got hot in just a couple of minuites.

The two radiator hoses are running 160 tempature.

Took the radiator cap off and in seeing bubbles. Not a ton, but there are some bubbles.

Does this mean blown head gasket?

If so what are my options? Either replace the head gasket or try one of those head gasket repair (some type of fluid) kits from the auto store?

 

[threeoaks]

Took the radiator out and cleanded it with a degreaser and washed it off.

Ran a radiator flush cycle through.

Added colant and ran the tractor. Got hot in just a couple of minuites.

The two radiator hoses are running 160 tempature.

Took the radiator cap off and in seeing bubbles. Not a ton, but there are some bubbles.

Does this mean blown head gasket?

If so what are my options? Either replace the head gasket or try one of those head gasket repair (some type of fluid) kits from the auto store?

 

[Jim L.]

The tractor is truly getting hot the overflow tank is bubbling and liquid is coming out of the drain tube from the overflow tank if you run it long enough.

Sounds that everything else has been checked or a diagnostic advice has been given.

Exhaust gas getting into the coolant will exceed the cap pressure limit and force coolant into the overflow tank. And bubbles can be seen in the top of the radiator. The logical step is to now check the gasket and cylinder head.

I would not use any quick-fix liquid or such.

Opening the little guy up is not the worst job. If you do have a gasket or head problem you don't want to let it become catastrophic.

 

[BruceP]

Have you tried any of the tests which I suggested to validate condition of the head-gasket sealing?

 

[motorhead]

Maybe a dumb question but are you trusting the Kubota temperature gauge? I'd be checking the temperature with a heat gun at the top tank of the radiator or with the cap off, checking the coolant temp with a thermometer.

 

[whitetiger]

Take the radiator cap off and inspect the area inside the neck where the cap seal makes contact. Is it smooth or is it rough and pitted?
If you have overheated the unit before, it is probably melted or distorted and can not seal.