Forum for air cooled diesel engines and clones

[Keaton85]

From what I’ve seen it’s the cheap Chinese clone parts that are inferior. The camshaft material is inferior with improper or no heat treatment. An oem Yanmar cam & bearing may be interchangeable which would solve that problem.
The quality of clone parts varies from terrible to good/great.
Are you saying the crankshaft PTO and rod bearings are wearing also?

90cummins

Thanks! That's what I figured when I read through this topic, I just wanted to check if I missed something.

I actually have a running "8.5Kw" Chinese diesel, and an original Winco 5.5Kw with a Yanmar L100 with unknown hours. This unit I just stripped down was one that did not get enough or probably any oil changes. Thus it has PTO end bearing wear and big end crank bearing wear, also cam fallow wear as well! This all probably caused the poor running, hot exhaust and in turn the dropped valve.

I have thought of either:
- Get a needle bearing with inner race and machine down the end shaft to press on the inner race.
- open up the crankcase bore on the bearing end and get a large ball bearing installed with some machining on camshaft.
- I noticed the Yanmar original camshaft at the gear end actually has a bushing bearing and not a ball bearing. The ball bearing could actually be causing the issue at the small end by allowing more movement. If the big end was changed to a double-row ball bearing that might keep it a bit more "straight".

 

[90cummins]

Did you say there is a ball bearing on the small end of camshaft not a needle bearing?
The plain bearing on the cam has not been an issue same with needle bearing in the crankcase. The problem is poor quality parts. Install genuine Yanmar parts & you should be good providing they are interchangeable.
90cummins

 

[90cummins]

Could you take a photo of cam & bearings.

90cummins

 

[Keaton85]

It's a needle bearing, the big end is the ball bearing, yet the Yanmar original has a bushing. My thought was to replace the needle bearing with either one with an inner race, or a complete ball bearing. The RPM rating only has to be 1800RPM, thus, its more about the pressure applied to that end.

The movement that I am concerned about caused by the big end bearing is radial, due to it be unbalanced on the small end bearing side. The bushing style on the original Yanmar might mitigate this issue.

I will post photos when back home in a few days.

 

[Keaton85]

Here is the damage: 350hrs, dropped valve.

 

[arto98607]

Ouch!

 

[90cummins]

Here is the damage: 350hrs, dropped valve.

You’ve got a mess there.

 

[bmaverick]

bump

 

[90cummins]

What are your plans?
Scrap or attempt to repair?

 

[bmaverick]

YANMAR OWNER MANUAL L70 L100 NDK6000YE.pdf