JD175A main bearing blew up

[rcavictim]

I spent last evening tearing into my JD175.  The small (timing end) crank main bearing (6209), has apparently been operating in a blown-up condition for quite some time making a shaking vibration that had me totally scratching my head.  The symptoms were made fuzzy because I also have a massive 180 lb. flywheel spinning on the same frame and the vibration occurred at a beat frequency between the big flywheel and the engine flywheel speeds and noticeable only at certain rpm's.  Last time I ran it it suddenly got a lot worse so I decided it was time to shut 'er down and tear into it.  At least four balls appear to have disintegrated taking out the rotating spider-carrier which was shredded and strewn about. Shrapnel was scattered all over inside the crankcase.   Now I know what was causing a curious mystery vibration!  My added neo sump magnet caught some of it.  My added full-flow spin on canister oil filter between the oil pump and the rest of the engine engiine has provided a clean supply of lube oil all along. These two DIY add-ons likely saved the engine from fatal damage given that I continued to run it for many hours after the initial bearing failure. No other damage that I can see.  Crank pin and lower rod bearing are spotless.  Must pickup a new bearing on Monday and get this little genset back in operating condition.

Since JD has a reputation for failures of their poor quality Chinese bearings, not using outsourced quality bearings like is done by Changfa, I should also replace the larger flywheel side ball bearing but I am dirt poor and that one may break the budget.  However, now is the time to get at it easy though since I now have the crankshaft out of the engine.

[rcavictim]

Here is a picture of more of the plant.  You can see the large outboard flywheel.  It runs ~1/2 of the engine RPM and completely takes out any flicker as well as making heavy motor starting loads a piece of cake for this low powered machine.  To minimize effort in the repair I did not drain the coolant system or disconnect the fuel system.

This genset goes a long time on a liter of fuel but only makes 2 kW AC. That was a deliberate choice to run the engine around 1800 RPM rather than 2600 RPM rated so as to prolong life and aid in fuel consumption penalty.  The alternator is a 4 pole Kohler that also serves as a starter motor and charger for the 12 volt starting battery.  It was a single bearing unit that I salvaged off the end of a multi cylinder gas Kohler plant and added a keyed tapered shaft and end bearing myself. This plant also sports a 2 kW 110 VDC generator head which us used as a jackshaft in the belt setup.  I want to eliminate this as I have no use for the DC and the parasitic load created by the DC generator just hurts efficiency.

[veggie]

Thanks for the pictures.
In your earlier posts, I had trouble picturing the flywheel arrangement.
It's a nice setup.
Good luck with your repairs.

veggie

[Henry W]

I wonder if you can change the timing end bearing to a roller type bearing.

Kubota put a roller type bearing on the timing end and use the massive ball bearing on the flywheel end.
I think the large ball bearing on the flywheel end keeps the crank from moving sideways.

If it can be done that might be a good thing to look into. A roller bearing should take more abuse.

You are lucky nothing else got damaged. The good thing it can be easily fixed.

Henry

[mobile_bob]

good job including a filter system and magnet, as you aptly stated, the engine would be only so much poor quality
scrap without them in place.

bob g

[Henry W]

The filter system with the magnet was cheap insurance and it seems like it paid off.

Henry

[rcavictim]

I wonder if you can change the timing end bearing to a roller type bearing.

Kubota put a roller type bearing on the timing end and use the massive ball bearing on the flywheel end.
I think the large ball bearing on the flywheel end keeps the crank from moving sideways.

If it can be done that might be a good thing to look into. A roller bearing should take more abuse.

You are lucky nothing else got damaged. The good thing it can be easily fixed.

Henry

Henry,

I'll look into the roller bearing option.  Thanx.

[Henry W]

rcavictim,

I would like to see the internals of the R175. Is it possible to take pictures of the geartrain parts, piston and rod, inside of crankcase cover, inside of crankcase, flywheel side and geartrain side of crankcase.

Henry

[rcavictim]

rcavictim,

I would like to see the internals of the R175. Is it possible to take pictures of the geartrain parts, piston and rod, inside of crankcase cover, inside of crankcase, flywheel side and geartrain side of crankcase.

Henry

Sorry Henry your request comes too late.  I was in and out of there at the beginning of last week and the engine is now repaired.

[Henry W]

Does the geartrain have helical cut gears?

Henry

[rcavictim]

Does the geartrain have helical cut gears?

Henry

No, they are straight cut, both are plated steel, maybe nickel?.

[Henry W]

Thanks again.

Henry

[rcavictim]

BTW I now believe the reason the original bearing failed was injector timing was set way too advanced from the factory.  I just added a 0.032" copper spacer shim in series with the original gasket also in place between the injection pump and the outside of the block. The engine runs much smoother sounding at 1400 RPM and no longer has a metallic snap that I could feel on the actual outside of the block before at the rear area of the timng cover where the outer race of this bearing is located.  I have not determined how much retardation that spacer gave me or where in actual degrees before TDC this is now firing.  Must make effort to measure this!

I guess you can't trust that the injection timing is set correctly on the cheap clones.  This brand new JiangDong came full of slimy stinky black oil inside and a load of sand in the pushrod galleries that kept contaminating the oil until I discovered it.

[mobile_bob]

RCA:

thanks for the description of the 175 bottom end oiling scheme, i find that proof of concept very interesting

a couple years ago, i proposed a similar system for the 6/1, where a hollow dipper could be fitted and made
to run in a trough/raceway, that was made to fit the arc of travel in the crankcase,

the raceway would of course only be in the bottom quadrant of the arc of rotation, but it would be good enough.

fitting the raceway to the sidecover, one could then install a fitting to admit pressurized and filtered oil from a small pump
such as one repurposed p/s pump from a small car.  this filtered higher pressure oil would keep the dirty oil of the sump displaced
in the raceway as well.

the additive pressures of both the pump and the motion of the dipper would provide quite positive oiling to the big end brg, and having
it well filtered would be a plus as well.

the idea never got put to use, mainly because folks might have thought it as unproven or too complex

the fact that the 175 oils the big end in this manner is quite interesting in my opinion.

after reading your report, if i had a listeroid i would be making the modifications for sure.

the interesting thing is, if the pump failed or threw a belt, the dipper would still have access of carry over oil from the sump
anyway, it would just not be filtered oil. so a pump failure would not cause an engine failure, just a failure of the filtration system.

also the top end of the raceway could be formed to direct the excess flow to an area of the engine where additional oil might be beneficial

the raceway could be built using some of that light guage steel channel such as used in dryway work, it comes in various sizes
a sizer crimper used to size the male end of round ductwork so it will reduce and fit into the next section could be used
to crimp the side of the channel and form the curve needed to follow the arc of travel of the dipper as it rotates about the bottom
of the crankcase.

bob g