Why is my D722 spewing oil out of the overflow tube?

[ekim22]

Guys I'm baffled on this one. This mower has been nothing but problems for me.

It boils down to how sensitive my mower is to overheating. The grass clippings from the deck get sucked onto the face of the air intake screen behind the seat, which in turn causes the engine to heat up, which causes the radiator to spit hot coolant/water on your lower back if you don't watch the temp gauge....making you think you've run over a nest of yellow jackets.

Anyways, my wife calls me at work and says the thing keeps overheating and was now blowing blue smoke. I told her to cut it off because she was burning oil at that point.

I get home to find the radiator dry as a bone and after filling that up, I have a hard time getting it to start.

After finally getting it to start, blue smoke pours out of it.....and after about 60 seconds the blue smoke stops coming out of the exhaust but then the over-flow tube coming out of the top of the engine block starts spewing oil onto the ground.

I drained the oil thinking maybe the block was full of burned up oil....but even after filling it back up with all new oil, it's still spitting oil out of that over-flow tube. I've confirmed several times that it is not over-filled with oil.

I'm lost. Did she maybe run it so hot that an o-ring or something worse (crack?) is causing oil to escape a piston? I'm really not knowledgable on small engines, much less diesels.

Anyone have any idea? Here's some pics of the tube in question

This is the tube in question that is now spitting clean oil and some smoke

This is where it goes into the engine block

 

[MBTRAC]

D722 head gaskets let go regularly if overheated so that's probably occurred, contributing to the oil "purging" & if you haven't left it overheating too long should be an easy/cheap fix unless the heads are warped/cracked or there's a damaged a cylinder liner - I wouldn't advise any further use until it's repaired otherwise you risk increasing the repair costs... the dry radiator is a bad sign

For the overheating, firstly check/replace the themostat as on the D722 they often fail, also depending on the application filling the cooling system can be a work of art "force feeding" up to 4quarts of coolant (I have 3x D722 in gensets/pumps) the trick is to have a funnel which extends below the bleed hole & slowly fill - make sure yours is filled with the correct volume.
And if it was my machine (I have no direct knowledge of your D722 application) I'd be shrouding the radiator (either completely or with side screens as primary filters - metal insect screen should suffice) so air is mostly picked up from above the seat back ( than as in your photo's unsreened from the sides/below) - one of the downsides of Z-Turns is the crud they picked up in dry/harsh conditions on the rear mounted engines (compounded by the forward facing radiator on your machine )

 

[ekim22]

Thanks MBTrac.

I guess it's bound for the shop. It's bad timing because I've been working non-stop for the past week and a half and haven't had time to cut the grass....and we have a real estate agent coming over Monday (as in tomorrow) to take pictures of the house so we can put it on the market. Not sure what my gameplan is there now.

Anyways, I appreciate the feedback.

 

[173abn]

sounds to me like a HG also.Kinda strange yours tends to overheat like that.I get alot of grass that clogs the removable screen but the temp gauge never gets to the green.Does yours have that screen in front of the rad.?hope you get it fixed...russ

 

[ekim22]

Yes mine has the removable screen in front of the radiator.

How big of a job is the hg replacement? Special tools involved?

 

[173abn]

I replaced the HG on my Yanmar tractor a couple yrs ago.You need not only the HG but a gasket for the valve cover,water pump gasket.you need to disconnect the injectors to get the head off.when you get the head off you prob. should take it to a machine shop to inspect it for warpage and cracks.do'nt know how many hours you have on the machine but I had new valves ,valve stem guides and springs put in mine.I also used new head bolts when I put it back together because the old ones were prob. stretched when they got torqued on .I had to reset the valves.I took a lot of pics during the tear down process because I had never done it before and bought a good manual.I really do'nt know if you can get a manual for your machine that goes into the detail you need such as valve settings ,head bolt torque and sequence etc. Perhaps if you get ahold of Kubota and tell them what engine you have they would have a manual for it.Prob. would'nt hurt to replace the fan belt while you have it torn down.I also put a new water pump on for piece of mind and had the rad. cored and cleaned out.I've prob. left out some things but hope this gives you a general idea...russ

 

[ekim22]

Got some bad news today.

Had it in the shop for about a week now and just got the diagnosis...

They're saying that after the initial pass over it appears to have busted or scored piston and they may get by with just replacing piston rings and rod bearings but are not sure if the cylinder itself is scored/warped.

They want $950 just to repair the piston portion, if the cylinder itself needs to be re-bored, obviously the cost shoots up.

We are moving to Minneapolis this fall and weren't planning on taking the mower with us. I told the shop to make me an offer on it.