L2900- head gasket (?)

[bmud]

I noticed my L2900 (1,200 hr) had no coolant in the reservoir so I checked my radiator. I ended up adding about a gallon of coolant. I have not had any overheating issues (it got hot once, but not dangerously so, when the radiator plugged brush hogging 3 years ago). Actually, the temp stays pretty close to L. I have seen it go up between L and H, but usually pretty low.

I pulled the dipstick. Oil is about 7/8ths up between the marks and while dark (due for a change), is not milky. No external coolant leaks anywhere. Engine starts and runs well. It blows greyish (not white?) smoke for a good 10-20 seconds on a cold start, but I attribute that to a cold start. I also don't run it hard enough too.

I added coolant enough to get some in the reservoir. When I start it, a constant stream of bubbles comes out through the overflow tube in the reservoir. Those bubble start up as soon as the engine is running (does not need time to warm up). When revved to PTO speed, an occasional large burp out of the reservoir happens.

I will be changing the oil soon (will see if there's water sign).

I'm thinking my two options are a leak in water pump (pulling in air) or a head gasket. I'm really hoping it's not the head gasket, but I'm starting to circle in around that

Questions

• What are your thoughts on this DIY-diagnosis?
• I'm reasonably handy and have done other medium level tractor mechanics (a few water pumps, starters, alternators, etc). I have a shop with all standard tools (would borrow a torque wrench). I should be able to do this right?
• I'm thinking of sticking with OEM gaskets because I don't want to go cheap on quality for this. That said, are there other brands of same quality with a reasonable cost savings?
• I'll probably get the upper engine kit so I don't have to screw around with reusing other gaskets upon install. Thoughts?
• Anything else I should do/check while I'm in there? I plan to swap delivery valve o rings (i have some weeping on top of the injection pump) since I'm pulling lines anyway. What about glow plugs for fun since I'm there ($20 each for NKG). Any reason to just plan to swap injectors while I'm there? I don't want to have to dig into the engine again lol.

 

[lugbolt]

that's usually head gasket or cracked head. Not uncommon for Kubota engines to exhibit that exact symptom when the head gasket is leaking. Seldom do water and oil mix on these and my opinion as to why is that the pressure in the cylinder is a LOT higher than in the cooling system and there is no (or very little) vacuum to "suck" it through a gasket.

little chance of a water pump pulling air in, without some sort of a leak-there is pressure in the cooling system and that pressure will force water out of wherever a leak would be. Fluids always flow from high pressure to low.

when you get the head off, have it checked for flatness.

yes use OEM gaskets. Don't skimp there.

Glow plugs? You can if you want. I don't unless they test bad and I test them. But I'm cheap, so keep that in mind.

 

[bmud]

I'm finally getting back to this and will be buying the head gasket kit soon.

One last set of questions. I'm leaking fuel on top of the fuel pump. I'm pretty certain its from one of the three plunger pumps out the top.

Should I replace 210 (o-ring), 050 (gasket, discontinued) or both from the attached diagram? I need to pull the fuel lines to do the head gasket, so I might as well tackle it while I'm there.

Also, can anyone confirm that if I pull the lock (070) and only remove the holder (060) I will be ok with the internals of fuel pump? I see conflicting messages on "don't mess with the lock"