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.