B6100 Engine rebuild impossible?

[sfixx]

I got a call from my local Kubota service manager this morning and now kind of feel like their has been a death in the family. I took the tractor in to have the low oil pressure light "on" problem diagnosed. The reply is that the pressure sending unit is okay and we cannot know more until we dig into the engine, however if there is much damage all the parts needed to fix it may not be available (including a remanufactured engine). I had already explained to the service manager that the previous owner drove the thing with the light on for quite some time which of course gives us cause for concern that the damage may be extensive(though it doesn't now smoke excessively). The PO has offered to fix the low oil pressure problem at his expense, but if we cannot fix the damage caused I'm wondering what's the point? I think that all the standard parts are available like bearings, seals, rings, and gaskets but pistons and some critical fuel system parts are not.

Got an Opinion on this? Has anybody run into a parts shortage with these motors? Are B6100's getting scrapped by the boat load? I thought that I had a great little tractor with outstanding parts support!

Thanks,

Steve

 

[robbieo11]

if you have them speced it seem as thougha good machine shop in yourarea would be able to assist in getting parts

if not try a bearing speacialty shop

 

[sfixx]

if you have them speced it seem as thougha good machine shop in yourarea would be able to assist in getting parts if not try a bearing speacialty shop

Yes, he said that custom machining may be the only option for some parts but then the repair costs increase dramatically

Thanks for your reply,

Steve

 

[sfixx]

The previous owner has agreed to pay the bill to replace the oil pump. $188 for parts and $450 for labor. It's a bit of a gamble but the shop is quoting 8 hours just to get into the crankcase to inspect and measure further damage. And since it's not smoking excessively, makes good power, doesn't burn oil or have oil in the water maybe we'll get lucky?

Does anybody have experience with low engine oil pressure related to any parts but a bad oil pump?

Thanks,

Steve

 

[TalonDancer]

...Does anybody have experience with low engine oil pressure related to any parts but a bad oil pump?...

In all engines....
Excessive smoking & burning oil--> bad rings or valve guides/seals.
Oil in the water --> bad head gasket, cracked head or engine block
These are the least of your worries in a engine run with low oil pressure.

I would not even consider just replacing the oil pump. Oil pressure is what keeps the _revolving_ parts from EVER touching (e.g. rod bearings, cam bearings, etc.) . It takes less than a minute of running with no (or very low) oil pressure to severely damage the "bottom end" of any engine. Without oil pressure, the rod bearings contact the crankshaft and begin wearing out the soft rod bearings immediately. If you are extremely lucky, the wear is confined to the bearings themselves. If not, the crankshaft will be scored and possibly out of round or undersized. This is not a "remove and replace" sort of job. Even in the simplest bottom end rebuild, you have to mic the crank and dial gauge the rods and engine block to see if there are bearings avaialble to fit these worn parts. You may also have to turn and polish the crank.

Talon Dancer

 

[robbieo11]

like the man said it could be the clearance on the bearings could be to far out causing the low presure. The smoke is exessve oil getting into firing chamber ie: worn valves guides or sealsthis also could be a sign of a worn or broken ring. You just do not know until it is torn down. The previous owner has committed to oil pump he therefore is assuming he is responseable. I would have him take care of the hole thing. if he will not have him eighter buy the unit backor take him to court for the repair costs

 

[robbieo11]

the other thing you can do is have him buy something like this Hustler 340 diesel lawnmower kubota engine commercial - (item 220134620704 end time Aug-05-07 22:00:07 PDT)

and work together to make engine work for your application

 

[robbieo11]

or this Kubota tractor B6100E - (item 150146700349 end time Aug-08-07 16:37:56 PDT)

 

[robbieo11]

here is a crank
KUBOTA B6100 CRANKSHAFT POLISHED - (item 230055931563 end time Aug-19-07 14:43:14 PDT)

 

[Willl]

That sounds like major surgery, seek a second opinion.

 

[wushaw]

It ain't all that bad to rebuild a little motor...tear it apart, take it all to a machine shop, get the machine shop work done and put her back together.

Sounds easy if you have done this before, if not then let someone else do it.

 

[ozzie tractor]

was this thing making some really bad rattles in the motor. i find it a bit hard to believe that a motor with very little or no oil pressure has not exploded in a shower of smashed metal. normally lack of oil pressure spins the big end bearings and the knocking which comes with a spun big end is fairly hard to miss. i agree with the above post. get a second opinion. have someone actually put a pressure gauge into the motor. it may not be the sender but another problem in the electrical system. it just seems odd to me for a motor to go this long with no oil pressure

 

[RobJ]

Did the shop stick a pressure gauge on the engine? Do you know what is the actual oil pressure? Most of the ground type sending units close the circuit about 5psi+/-. Low oil pressure usually means that clearances somewhere are high, but in most cases they are still getting oiled. A tight engine has higher oil pressure. I once had a CJ3B that would idle down to about 4psi, gas it and it'd spike up to 15. Never made a noise, probably still running. You could have engine wear all over the place, or one place real bad. Might even have a failed pressure relief valve spring.

In all my engine rebuilds I must say I never repalced a worn out oil pump, I replaced a lot of them but none had a total failure, they willusually put out plenty of oil and pressure.

On your tractor, if you rev the engine up does the light go off? I'd still want to see a pressure gauge on it when idling and revving. Personally I'd take the guys repair or see if he will take it back. Or just run it! Either way I'd put a mech oil gauge on there. You can also replace all the rod and crank bearings without removing the engine.

Good Luck,
Rob

 

[robbieo11]

i agree make them put a gauge on it

 

[sfixx]

Thanks for all the responses guys! I got the tractor back after the service and have had 2 days to run it. They replaced the oil pump and the pressure relief valve plus assorted seals, o-rings and gaskets. They did test the pressure before and noted 10 lbs at full throttle with zero at idle. After the service he told me it gained 2 lbs at full throttle but is still zero at idle. Before service the engine didn't make any really scarry noises but this is my first diesel and I figured the Mack truck sound is normal (firm knocking?). The biggest problem was that as the engine warmed up the low pressure warning light would illuminate at higher and higher rpms until after about an hour of work it would illuminate even at full throttle. Having a new or calibrated oil pressure sending unit would be good but you're right a true gauge would be best. I'll look into adding this asap. Now, I can work it hard and the the light doesn't come on, but after a full warm up if I idle back it gets to about 1/2 throttle before the light comes on. This is a much improved condition. The engine does smoke some, especially under a good load it will start to huff as it works up some "steam". Even at lower rpms it will sometimes send out little whispy smoke signals.

The previous owner is going to pay for this $700 service so I'm happy to let the matter go at that. I got the tractor for a bargain and will keep my eyes out for a parts tractor or spare motor. My local service shop was talking about better that $3,000 for an engine rebuild, which is more than the tractor is worth I believe. I don't have that much work for her and hope to nurse it along for a while.

Thanks again for commenting,

Steve