I have a Kubota KX121-3 with I think 4300 or so hours on it. It's a very nice clean machine in almost every way. I love the thing, 6 way blade, smooth, generally a great machine for me. I don't use it professionally just around my property. The thing is that it has what seems to me to be a lot of blow by. I open the oil cap and what seems to me lots of splatter comes out. Of the other dozen or so diesel engines I have and have had none like this one. It starts easy, seems to have plenty of power, doesn't smoke much or use much oil. Is this anything to worry about?
Welcome to the HEF. How is the lube oil level? Overfilled? What oil do you use? Is the blow-by severe enough to push the dipstick out? I would check the crank case vent to make sure it’s clear. I suspect the vent to be plugged up with those West Virginia mud daubers. Knowwhatimsayin?
It was this way when it came to me from NY. Maybe NY mud daubers? Oil level is good, i changed it when i got it (less than 100 hrs ago). Used Rotella 15w-40. I never looked for or at the crank case vent. I will check. Thanks for tge reply.
Where is the fill cap located? Lots of Kubotas are located hust above the oil pan and open to the sump. If that's the case, it will definitely spray back at you. Try the cap on top of the valve cover if it's not the one you have checked.
These are all good points. I can’t quite remember the lay of things (where the cap is). I didn’t get to look at it today. My dump truck is all torn apart so focused on that. I will revisit this andvreport back.
All inline four cylinder engines do pump air in AND out the filler cap when you remove it with engine running and at the same time this pumping action tends to spit out a fair bit of oil. This pumping action can very easily be confused with a big blow by. The reason is the following: Assume two pistons is at top dead center and the other two is at bottom dead center. Now you have some specific air volume under the pistons inside the engine. Turn the crank exactly 90 degrees. Now all pistons is at the same height in its bores, but crucially this height is NOT halfway between top and bottom dead center, the height is actually quite a bit below the middle between top and bottom dead center. The reason for this is the con rod is sitting at quite a bit of an angle in this crank position making the effective con rod length shorter. Thus the sum of the volume under each piston is now LESS than the sum of the volume when two pistons is at top and the other two at bottom. This reduction in internal volume inside the engine will cause a very short pulse of air letting out of the open oil filler cap. Now let the engine turn 90 degrees again, now the other two pistons is at the top and the first two is at bottom dead center. Now the internal engine air volume under the pistons is at maximum again and there will be a very short pulse of air sucked into the filler cap. So, for half a revolution of the crank we have got one full puls (out and in again) of air through the filler cap, or in other words, we get the double number of air pulses at the filler cap than the rpm of the engine. Say we are idling at 800rpm. Then we get 1600 pulses a min or 26 and 2/3 air pulses a second at the filler cap. I am not saying your engine is in perfect order with no blow by, but it is important to be aware of this peculiar perk of an inline four cylinder engine. It is all too easy to confuse this pulsing of air and spitting of oil droplets to instead be a large blow by. I think this excavator has a Kubota V2203-M (non turbocharged) engine? These engines is VERY tight regarding engine blow by when in good order. I think those engines must be among if not the tightest engines I've ever come by regarding the amount of blow by tey have, or rather the lack of blow by they have.
Sorry for the delayed response. I had one all typed up in my iphone (hate the thing) and for some reason i was not able to post it. Thanks for that response. Yes it’s the v2203 engine. All my other Kubota engines that i am comparing it to are 3 cylinder. This is good info! I looked a little more at the crank case breather and I think there’s some sort of diaphragm/oil separator thing in the valve cover. I can’t see a good diagram of that. I will put checking valve clearance on the list and check this out when in the near future. Also, I should add that the most accessible oil cap, the one that I opened to check for blow by, is pretty low down near the top of the crank case. There is another cap in the top of the valve cover.
If you are taking off the filler cap that is installed directly on the top of the oil pan, if your engine has that type of oil pan, then there for sure will be spitting out a lof of oil even on a perfectly good engine. Also this engine has no balance shafts, that means the second order vibrations are not canceled out. This vibration is the engine jumping straigth up and down twice for every cranck revolution, albeit only probably less than one tenth of a millimeter. This jumping might tend to increase the oil spitting from an opening near the oil level in the engine as is the case with those Kubotas that have the oil filler neck installed directly in the top of the oil pan.