B7200 Fuel in Oil

[Fellenz]

Hello Everyone,

I believe I have an issue with fuel getting into the oil on my B7200. I say believe only because I'm sick with a cold and can't smell anything, the oil level on the dipstick is very high and when I passed the dipstick around other people were able to confirm it smelled like diesel.

I believe this can either be caused by a sticking injector or a blown seal on the injection pump. The engine runs strong and doesn't smoke so I'm leaning towards a pump seal. Are there any other possible causes?

Possibly related is the engine stop lever on the injection pump. The lever on the pump itself is frozen and it seems like something internal might be locking it as it went from working to frozen pretty much overnight.

Where should I start troubleshooting? I really can't afford to have this tractor torn apart right now unless absolutely necessary so I'd hate to overlook something simple!

-Thanks,

Erik

 

[ShaunRH]

Had the same issue on my D-17. Had to rebuild the injector pump with new seals. No more leak into the oil pan...

 

[North Idaho Wolfman]

The other possibility would be a bad lift pump, but I would say with the stop lever problem your looking at something wrong with the injection pump.
That is not cheap or easy, you going to have to tear into it and get the pump out and take it to be rebuilt, you can't rebuild it yourself properly.
I wouldn't recommend running it with fuel getting in the oil as it thins the oil and can cause bearing damage fairly quickly, then you would be looking at a very expensive repair bill.

 

[Fellenz]

The other possibility would be a bad lift pump, but I would say with the stop lever problem your looking at something wrong with the injection pump.
That is not cheap or easy, you going to have to tear into it and get the pump out and take it to be rebuilt, you can't rebuild it yourself properly.
I wouldn't recommend running it with fuel getting in the oil as it thins the oil and can cause bearing damage fairly quickly, then you would be looking at a very expensive repair bill.

Thanks for the reply. Not what I wanted to hear but about what I expected unfortunately!

I had an issue on another tractor dumping fuel in the oil through a blown out cam driven lift pump. How is the lift pump on the 7200 driven? If the lift pump is a possibility I'd like to start there as it will likely involve less tear-down than removing the injection pump.

-Thanks,

Erik

 

[Daren Todd]

If the lift pump is mechanical and bolts to the side of the block then it could be leaking through a seal internally. If it's an electric pump, then it wouldn't leak fuel into the oil.

 

[Fellenz]

If the lift pump is mechanical and bolts to the side of the block then it could be leaking through a seal internally. If it's an electric pump, then it wouldn't leak fuel into the oil.

Well I did a little looking online and it appears the tractor has a cam driven lift pump. I'll run down to the shop in a few to confirm but assuming the internet is correct I'll start by pulling the lift pump.

-Cheers

 

[Fellenz]

The lift pump is off. I opened in up and see some minor cracking on the outer edge of the rubber diaphragm. It doesn't appear that any of the cracks extend to the area where it is driven but I'm inclined to replace the pump anyway, change the oil and see if my situation improves. If I see fuel in my oil again I guess I'll be pulling the injection pump.

 

[Fellenz]

The fuel lift pump is disassembled. I don't see any areas where the diaphragm would be obviously leaking but it is cracked on the edge so I'll replace it for peace of mind.

On the injection pump, looking it my parts book it appears the pump is driven by the fuel camshaft and is bolted to the top of the block. With the injector lines and fuel lines removed can I simply remove the bolts and lift the pump upwards or is it connected to the camshaft?

I also don't see any internal pump parts called out. I'm assuming this means the pump is replaced as a unit or rebuilt by kubota and parts are not available to end users, correct?

-Thanks everyone,

Erik

 

[ShaunRH]

Injection pump repairs aren't for the faint hearted. You have to take the proper steps prior to removal and then have the right tools for the job once it is apart. It has made me nervous in the 3 times I've had to do it!

It sounds like you aren't lucky enough to have a 'common' injection pump. From what I've read on the history of this if it was in the 50's through early 70's era, there were only a few pump makers and they all just bolted on. They were made to be field repaired if need be. Then the more intricate pumps started coming out and some could be repaired by the user, some needed shop time. Sounds like you have the latter.

All injector pumps need rebuilds every so often (years or hours, either one wears on it), so I'd just chalk it up to "it's time" and have it done, at least you get a warranty on it. Sometimes you can just buy a rebuilt one and submit your old one as a 'core' for about the same as you'd pay to have yours rebuilt. Those usually come with new hardware as well as seals so if you can get a deal on that, it's a good way to go too.

The only thing I recommend is putting #1 cylinder on top dead center (on the right stroke, usually compression) and marking the gears where they touch (there is frequently already a dimple or line in both gears at that point, if not, mark with a solid scribe to make one). This will make sure your pump is still 'in time' when you put it back together (assuming the pump gear is keyed, if not, you will have to set the pump to TDC position and line up the gear... ugh!).

Now, if I've made you nervous enough, having a good, reputable tractor mechanic do it is probably the best way to go, it just costs a bit more...

 

[Fellenz]

Well right now I have a new lift pump on order (only $4 more for the entire pump vs. the diaphragm alone!). Once the new pump is installed I'll run it and keep a close eye on the oil level. If I see it rising I'll pull the injection pump.

I have a few shops I've worked with before that I'll be calling to quote a pump rebuild. I also checked with Kubota and they want ~$800 for a new pump which sounds pretty reasonable.

I know I'm not rebuilding the pump myself. I was only asking about parts availability in the off chance that this pump has simple oil seals that could be serviced. I've done nose seals on Bosch injection pumps and similar and if the Kubota was a similar design I'd be comfortable dealing with it.

Seeing how the pump appears to be cam driven it's not something I'd want to mess with.

I am my own tractor mechanic. I can't afford to haul old junk to a dealer or independent mechanic so I've done everything from hydraulics, transmissions, to out of frame rebuilds.

 

[ShaunRH]

All of the ones I've worked on have been gear driven. The most complex one I've done was off an old Cat diesel (can't recall the model right now) but it was a beast and was completely frozen up inside. It did have the advantage of pulling off the main side plate and you could get to about 90% of the parts in the pump.

I haven't played with a cam driven pump yet but I'd be nervous about that too. You make one mistake with those puppies and you can have a runaway on your hands. I keep a flat board nearby to slam across the intake pipe if it starts to runaway on first start...

 

[North Idaho Wolfman]

Yes it's a cam driven injection pump, and getting parts and seals is a real pain in the back side, most rebuilders can do it without a problem because they buy the parts in bulk, the other bonus is they will also test it to make sure it's working properly.

You will need to pull the side engine stop plate and the front throttle control plate, carefully remove any springs (do not let them fall in as that will mean a lot more work!).
When you pull the injector pump it just rides on the cam, no physical connection.
pull the pump and remove and save any shims under or on top of motor, that is super important as that is how the timing is set, after a rebuild just reinstall the same shims.

If you don't have them go to Kubotabooks.com and download both the OPS and WSM for your tractor they will give you a lot more insight!

 

[Fellenz]

Thanks for all the help everyone!

I feel like I have a pretty good handle on the injection pump removal process.

I'm ordering a new lift pump and gaskets this afternoon in the off chance that it's my problem. If I still have the fuel in oil problem after I replace it I'll likely be back with more questions.

-Thanks again,

Erik