Kubota kh66 d1402b dirty coolant

[John V]

Hey, I've got an older kubota excavator with a d1402b engine. about 4500 hrs on machine. Engine occasionally pushes coolant to the overflow bottle and runs low on coolant, so I keep an eye on the temp gauge. When it runs hot I'll check the level in the radiator and it'll be low. Top it off and runs fine until it's lost more.

Replaced the water pump as I saw a small drip from that. No other leaks noticeable except for the coolant getting pushed to the overflow bottle. The coolant in the overflow bottle is dirty/mixed with oil. I recently did an oil change in the past 30hrs and the oil was good (not a milkshake).

I don't think this engine has an oil cooler. I'm guessing that leaves a blown head gasket as a source of the problem? Would I see any other noticeable symptoms to confirm it's a head gasket before I take apart the head?

Thanks,
John

 

[Acoals]

Might be a good idea to pressurize the radiator and monitor it for awhile

 

[John V]

Put a pressure tester on the radiator and ran the engine. I rises to ~15-16psi in about 30 sec. Bled off the pressure a couple times to make sure it wasn't just air in the system and it kept returning to 16psi. Did a little work with it for 10 min, hopped out and checked the pressure gauge and it was about 18psi. Was also leaking coolant around the gauge adapter cap. Thing comes with a 13psi cap, so I'd assume it's intended to run below that? The d1402 engine manual specs the cooling system as: "pressurized radiator (12.8psi) Forced circulation (with water pump)".

 

[Acoals]

Put a pressure tester on the radiator and ran the engine. I rises to ~15-16psi in about 30 sec. Bled off the pressure a couple times to make sure it wasn't just air in the system and it kept returning to 16psi. Did a little work with it for 10 min, hopped out and checked the pressure gauge and it was about 18psi. Was also leaking coolant around the gauge adapter cap. Thing comes with a 13psi cap, so I'd assume it's intended to run below that? The d1402 engine manual specs the cooling system as: "pressurized radiator (12.8psi) Forced circulation (with water pump)".

It rises to 15psi in 30 seconds with a cold engine? If so most likely then it is leaking compression into the water jacket.

 

[John V]

It rises to 15psi in 30 seconds with a cold engine? If so most likely then it is leaking compression into the water jacket.

Yep, cold engine. When it was warm was looking more like 18psi. By water jacket you mean the coolant channels sealed by the head gasket right? So my plan of attack will be taking off the head, checking for flatness, dropping off at machine shop if necessary, and new head gasket. Sound about right?

 

[Acoals]

Yep, cold engine. When it was warm was looking more like 18psi. By water jacket you mean the coolant channels sealed by the head gasket right? So my plan of attack will be taking off the head, checking for flatness, dropping off at machine shop if necessary, and new head gasket. Sound about right?

Yes, I mean the coolant passageways in general.
Not actually seeing the machine I would hesitate to make to many pronouncements on what ought to be done, but if I thought it was a head gasket I would pull the head, check the gasket and straightness, and send it out to be pressure checked and decked. I don't know anything about that particular engine, but cracked heads are common enough that I would sure want to make sure the head was sound, not just straight.