Oil blows out overflow on Kubota B5200

[Bladeharvest]

Hi,
I have had the little B5200 now for years without any major problems. Just the other day it began blowing oil out of the overflow.
I checked the oil level and it was overfilled. No one added oil. I could not smell diesel in the oil but it was a little thin.
I changed the oil and made sure it was at the correct level before running again. It ran for 2 days before it happened again. I checked the oil every couple of hours and it was fine. On the last check at the end of the day it was overfilled again.
Obviously diesel is getting into the crank case. I have been told that the first place to look is for a bad injector. The tractor runs fine. Does not blow black smoke except when first started or when the accelerator is leaned into hard. It idles fine and does not sputter nor ping.
I was also told that it could be coming in through a worn fuel pump.
Any ideas on how to troubleshoot this is greatly appreciated. Thanks!

 

[Gary Fowler]

Had that happen on a D 17 AC tractor many years ago and it was a blown seal on the injector pump drive shaft which allowed fuel to go directly into the crank case.

 

[Hooked_on_HP]

How much is it over filling, a quart,gallon or more. It would have to be way over full to cause it to come out the breather if that is the only problem. Does it have a lot of blow by. When running put your hand by the blow by tube and see if you have a lot of blow by.
Bill

 

[joecdeere]

check the diaphragm on the mechanical fuel pump, if it fails fuel gets into the crankcase

 

[Bladeharvest]

It tends to blow out when running at high revs. Slow down and it stops for a while. Run at high speed again and it spurts out. Not in a continuous flow but intermittent. It can run for quite a while before it happens again. When I changed the oil I suspected a sticky injector. But it ran all day just fine. I checked the oil at the end of the day and it was exactly right. Ran it the next day and checked at the end of the day and it was overfilled.

 

[Bladeharvest]

Could it be a sticky injector?

 

[Dan W]

Good morning all,
Regarding engine increasing oil levels, a fuel leak condition at the fuel injectors (bleeding down into the crankcase) is a good suggestion but belongs to a different injector design. With the pencil or needle type injectors Kubota uses on their engines, this next to impossible.

With this injection design, charging pump, injection pump and needle injectors, fuel pressure from the injection pump forces the injector needle upward opening a port where fuel can be atomized and delivered into a pre-combustion chamber. Once the fuel is injected; there is no residual fuel to bleed down into the crank case.

The most likely cause of this condition (as stated by Mr. Bladeharvest) is a failure at the fuel transfer pump itself. So, go to the easy one first (replace transfer pump). If this does not rectify your oil dilution issue, the last alternative is to replace the injection pump camshaft front seal.

Lastly, if the fuel transfer pump diaphragm has a significant hole in it, you should experience a hard start condition. It would take more time until there is enough transfer pump fuel pressure to the main injection delivery pumps, inside the fuel injection pump assembly, to build-up injector pressure.
Good luck with the fix.

Dan

 

[Bladeharvest]

Thanks Dan,
The tractor starts up easy enough. I guess that the fuel pump would be the first item to check.
Thanks to all for the great replies.

 

[Dan W]

You're quite welcome... I had the exact thing happen to me on my Cummins / Onan diesel generator set (Onan 34HP, 3 cylinder diesel, with rotary distributive type injection fuel pump). You'd think you could buy just the diaphragm, it would be simple enough to replace, but not so, had to pay 100+ from a pump.

Dan

 

[mitch becton]

several years ago had same problem with over the road truck we ran with detroit engines turned out to be a 1.00 copper o-ring at injector mount. trucks would go out in morning oil level great come back at end of day oil running out of motor. after several days of running in circles we found the copper o-ring worn out.