Kubota 1140 CPX Overheating

[ufcxl]

Howdy all. Made a smart purchase at auction (didn't read description because I was under the reserve: Ha- they lifted the reserve and I got it - cheap but,...).
Was told it overheats and needed new head gasket. Did a test on the radiator with check fluid. It stayed blue (3 tries). Changed oil, no froth or bubbles there. No steam or smoke from tail pipe.
It runs cold for a while then temp spikes, then drops quickly, then repeats until it overheats. Stays cold at idle, only overheats under load. Funny in that it blows the top off the overflow reservoir and blows steam and water. Seems like I'm getting air in from somewhere and loosing coolant. Replaced thermostat and also ran without one, flushed radiator and engine until water ran clear.

I'm stumped. Maybe the head gasket is blown? It is a diesel.

 

[chris142]

Send in an oil sample. That will tell you if there's even a trace of coolant in the oil

 

[Russell King]

It does sound like a blown head gasket. I believe you can test it a couple of ways.

1) While cold remove radiator cap and start engine. Look into the radiator and see if there are small bubbles visible in the coolant. You may have to let it get hot and see if the bubbles start then???

2) Get a test kit that can find combustion products in the coolant.

Here are a couple of different test methods:

Amazon.com

6.0L Blown Head Gasket & EGR Cooler Bubble Tester

This tool helps test your truck for blown head gaskets, a blown EGR cooler or both. Simple and easy to use, you can see it in action in our videos.

bulletproofdiesel.com

 

[ufcxl]

I did the test kit and also the bubble test. Test kit was negative but there are bubbles. But they're big and not constant.

the temp rises and then falls. Like the thermostat wont stay open. Rises to redline then falls to almost cold. Also, seen zero steam from tailpipe.

 

[GreensvilleJay]

Any chance you put the new thermostat in backwards ?
What you describe, hot-cold-hot-cold... does sound like a 'stuck stat'.....
curious for sure

 

[ufcxl]

Any chance you put the new thermostat in backwards ?
What you describe, hot-cold-hot-cold... does sound like a 'stuck stat'.....
curious for sure

Pretty sure no, but I've done sillier things. I plan to retry without it to confirm theories. Hoping not to have to replace the head gasket (or at least confirm that's what it is.)

 

[GreensvilleJay]

Curious, I'd expect a 'blown head gasket' to constantly heat the coolant up and up, not the 'hot-cold-hot-cold' that you describe...

 

[whitetiger]

Check the seating area in the coolant fill port where the cap seal contacts. See if it is smooth, deformed, or melted.

If it is damaged, the cap will never seal, and it will fill the surge tank until it blows the cap off. If this is the case, you will need to replace the fill port and probably the pump.

 

[ufcxl]

Frustration update: swiched out water pump. Took thermostat out and see good water flow. Temp is low at idle. Under load (higher RPMs) temp continues to go up to redline, then back low (like a bad thermostat). and repeat.

Starts and fine and runs as smooth as glass. good power. Zero steam out tail, no water in oil. Do get bubbles in coolant but did the fluid test and it stayed blue.

Question to the group: Wouldn't there be at least one indicator of a blown head gasket (steam, water in oil, oil in water) and wouldn't it run rough?

 

[ufcxl]

New idea: The buggy has a transmission oil cooler. Since the temp spikes then drops, could it be a but in the trans that's causing a bunch of heat? That would tie with it not getting hot while idling, only when moving.

Props to the tech support folks at Messicks for helping me with this thought.

 

[GreensvilleJay]

hmm, any chance it has an inline, rad hose style , coolant heater ?

does it still cycle like a bad stat(cold-hot-cold.....) IF the stat is removed ?

only so many straws in the bale to choose and most you've done......
sigh... I sure hope you find out what it is !

 

[ufcxl]

hmm, any chance it has an inline, rad hose style , coolant heater ?

does it still cycle like a bad stat(cold-hot-cold.....) IF the stat is removed ?

only so many straws in the bale to choose and most you've done......
sigh... I sure hope you find out what it is !

I am turning every bale over before I tear into the engine. Read a note where a guy's brakes were hanging up and causing engine to stress and overheat. Will check that too.

Otherwise, looks like I'll be getting my hands dirty.

 

[DaveFromMi]

Temp cycling like you describe sounds like a sticky thermostat, Another possibility is the stat "jiggle pin" may be stuck closed. The stat should dampen out and modulate temperature without excessive swings. Yours seems like step changes. Stat should be replaced.

 

[ufcxl]

Temp cycling like you describe sounds like a sticky thermostat, Another possibility is the stat "jiggle pin" may be stuck closed. The stat should dampen out and modulate temperature without excessive swings. Yours seems like step changes. Stat should be replaced.

Replaced and also ran without one. Same results. The spikes act like sticky stat but with no stat, still spikes.

 

[GreensvilleJay]

OK, humour me.

does it ACTUALLY overheat or are you just going by what the temperature gauge says ?
maybe the gauge is bad( or the sensor ).
if you have an IR gun, remove rad cap and monitor how hot the coolant gets .
Maybe TEE in another sensor and gauge ??

I can't think of anything in the cooling system that can cause hot-cold-hot.... when the stat is NOT there.

it's a real head scratcher !!

 

[#40Fan]

Common symptoms of a blown head gasket or cracked head.

 

[ufcxl]

Common symptoms of a blown head gasket or cracked head.

Then why no steam or contamination? Also did the combustion gas test. Rabbit didn't die (the fluid stayed blue in 2 tests). Also the temp wouldn't fluxuate between cool overheat then cool. Unless there's a part of the headgasket that blows then reseals then blows. But I would still have steam out the tail. And some kinda contamination.

 

[ufcxl]

OK, humour me.

does it ACTUALLY overheat or are you just going by what the temperature gauge says ?
maybe the gauge is bad( or the sensor ).
if you have an IR gun, remove rad cap and monitor how hot the coolant gets .
Maybe TEE in another sensor and gauge ??

I can't think of anything in the cooling system that can cause hot-cold-hot.... when the stat is NOT there.

it's a real head scratcher !!

Used the IR to confirm overheat. I'll probably tear into it soon. Worst case another ranch project to complete.

 

[Russell King]

The other side of the cooling is the air side. If you have an electric fan, fan clutch or something similar you sh verify they are working properly. As far as I know your fan is directly connected to the pulley so can rule those out. But replace the belt and pulley to ensure there is no slipping?

I can’t think of anything that would block and the not block air flow but you can try cleaning the radiator exterior (and interior) surfaces to see if that makes any difference in the performance.

You seem to have eliminated the water side problems. But the only remaining “problem“ on the water side that I can think of is an insufficient fill due to an air pocket. I have no idea what that does but perhaps use one of those fancy vacuum radiator filling systems?

I would look at the air side for sure but that is a stretch of imagination.

 

[ufcxl]

The other side of the cooling is the air side. If you have an electric fan, fan clutch or something similar you sh verify they are working properly. As far as I know your fan is directly connected to the pulley so can rule those out. But replace the belt and pulley to ensure there is no slipping?

I can’t think of anything that would block and the not block air flow but you can try cleaning the radiator exterior (and interior) surfaces to see if that makes any difference in the performance.

You seem to have eliminated the water side problems. But the only remaining “problem“ on the water side that I can think of is an insufficient fill due to an air pocket. I have no idea what that does but perhaps use one of those fancy vacuum radiator filling systems?

I would look at the air side for sure but that is a stretch of imagination.

It's a electric fan on the radiator and it runs all the time. The air pocket idea came up. We jacked up front end and tried to burp it.

If the overheat was constant, I would have already torn into the head but since it spikes up and down with zero other signs of a head gasket or cracked head, I have reframed. I guess once everything else is eliminated.... I plan to flush out the hydraulic cooler lines (not sure they cleared and check the temps there while moving. Also plan to rev up in neutral to see if movement or just engine rpms create the spikes. MTF.