Forum for air cooled diesel engines and clones

[90cummins]

After relapping the valves and double check them with break cleaner, the engine still does not start. Next step is to check the pistonrings. I didnt wanted to tear the engine apart but i have no other joice i guess

Was there any leakage by valves after lapping them??
There are two things I would do before tearing it down.
With injector removed connect it to fuel pipe and crank it over to check injection pattern.
Then remove the oil strainer and see if it is clean or have metal contamination on it.
90cummins

 

[shanana]

There was no leakage after relapping.
The spraypattern looks like it should, compared to YouTube Videos.
Nice straight 4 sprays.
I changed the oil when the generator came to my shop. No shiny metal or something unnormal. Used but ok.
Even with diesel direct to the inletport it wont fire up.

Thank you for the welcome. The valves work correct, also the timings at tdc are ok.
I will record a video

 

[90cummins]

Did you pull the oil filter screen out??
Squirting diesel into intake will not start it.
Starting fluid is NOT recommended I’ve seen it break the piston ring land.
Is your compression tester accurate up to 400+ psi?
Another compression test would be informative.
Could you elaborate on its previous history & use. Are you 1st owner, how many hours are on it, how was it running when you got it, how much load was on it and how long did run at load??
Was it running fine when shut off or did it stop on its own?
I’m thinking the compression is low because of extended operation with very light load and/or cold temperatures.
If you squirt some oil into cylinder if rings are the problem it may allow you to get the engine started. If you have 2 preferably 3 or more 1500 watt heaters to load the generator if it starts you may be able to avoid a teardown by running it close to full load for a couple hours.
Cylinder bore glazing is a real problem for diesels large & small if run lightly loaded or cold.
Good luck looking forward to more details
90cummins

 

[ponytug]

+1 on some oil in the piston to see if it starts/runs.

I am still a bit curious on how you tested the compression, as it isn't something some (many? most?) mechanics have an easy time with on these engines. Just a point of uncertainty.

If the oil doesn't fix it, and it was running when it suddenly stopped, I would suspect something that requires disassembly.

All the best,

Peter

 

[shanana]

I will answer the other questions later

 

[ponytug]

I will answer the other questions later

The videos are very clear. Thank you!

My opinion after seeing the first video is that it pretty clearly demonstrates no compression. I'm sorry but I think that you will need to take the engine apart. Hopefully, it is something simple such as a blown ring.

All the best,

Peter

 

[90cummins]

If it comes to a teardown theses are very simple.
It’s important to remove pushrods & injection pump prior to removing side cover. The cam is supported by a very small needle bearing and can be damaged.
Good luck

90cummins

 

[shanana]

Did you pull the oil filter screen out??
Squirting diesel into intake will not start it.
Starting fluid is NOT recommended I’ve seen it break the piston ring land.
Is your compression tester accurate up to 400+ psi?
Another compression test would be informative.
Could you elaborate on its previous history & use. Are you 1st owner, how many hours are on it, how was it running when you got it, how much load was on it and how long did run at load??
Was it running fine when shut off or did it stop on its own?
I’m thinking the compression is low because of extended operation with very light load and/or cold temperatures.
If you squirt some oil into cylinder if rings are the problem it may allow you to get the engine started. If you have 2 preferably 3 or more 1500 watt heaters to load the generator if it starts you may be able to avoid a teardown by running it close to full load for a couple hours.
Cylinder bore glazing is a real problem for diesels large & small if run lightly loaded or cold.
Good luck looking forward to more details
90cummins

The filterscreen was clear with no metal parts or other particles.
iam the first owner with round about 9h. It was used when it was frosty outside and was loaded with a 1500W heater. It stopped working suddenly. Before it was runner for two hours.
i think i cant get along a teardown

 

[90cummins]

I found an article about diesel cylinder glazing years ago it is not my article unknown source.
90cummins

 

[bmaverick]

I found an article about diesel cylinder glazing years ago it is not my article unknown source. View attachment 852925View attachment 852926View attachment 852927View attachment 852928
90cummins

Found the article you took screen shots with a camera yeas ago.

https://www.fischerpanda.com.sg/uploads/4/3/5/6/43569463/carbon_build-up_and_cylinder_glazing.pdf

And the same stuff is a section in this genset manual too,

https://www.zurichna.com/-/media/Project/ZWP/ZNA/Docs/RiskEng/HurricaneTK/DIesel%20Generator%20Operations%20and%20Maintenance.pdf

 

[bmaverick]

Found the article you took screen shots with a camera yeas ago.

https://www.fischerpanda.com.sg/uploads/4/3/5/6/43569463/carbon_build-up_and_cylinder_glazing.pdf

And the same stuff is a section in this genset manual too,

I found an article about diesel cylinder glazing years ago it is not my article unknown source. View attachment 852925View attachment 852926View attachment 852927View attachment 852928
90cummins

https://www.zurichna.com/-/media/Project/ZWP/ZNA/Docs/RiskEng/HurricaneTK/DIesel%20Generator%20Operations%20and%20Maintenance.pdf

This is one reason why I try not to idle my diesel engine long. Yanmar even states not to idle more than 10mins at a time, and not to idle for 5mins and then turn the engine off.

I run the engine, gracefully lower the rpms, then shut down. Keeps the engine healthy and is a good practice. No glazing on these cylinder donuts with holes.

 

[90cummins]

Found the article you took screen shots with a camera yeas ago.

https://www.fischerpanda.com.sg/uploads/4/3/5/6/43569463/carbon_build-up_and_cylinder_glazing.pdf

And the same stuff is a section in this genset manual too,

https://www.zurichna.com/-/media/Project/ZWP/ZNA/Docs/RiskEng/HurricaneTK/DIesel%20Generator%20Operations%20and%20Maintenance.pdf

This is good info for anyone thinking of buying a generator diesel or gas.

90cummins

 

[90cummins]

I built my nephew a generator several + years ago using a Yanmar L70 diesel from eBay which needed rebuilding. New rings, camshaft lifter & rod bearing plus seals & gaskets. A belt drive 5kw generator was purchased also along with taper-loc bushings so I could mount a pulley on the shoulder of the crankshaft which was tapered for a direct drive generator.
Belt drive was chosen because of the ability to use any motor source to run it. It also allowed us to overdrive it with the appropriate pulley to reduce engine rpm.
It was sitting in the corner of my shop since it was first built & tested & I thought it is time to pull it out & check it.
There was fuel in it so I connected the battery & it cranked & cranked
Very unusual to not start within 1 or 2 revolutions.
Found the injector rack was stuck closed, fortunately.
Removed injection pump hit it with some blaster worked it until it was free then reinstalled it. Cranked it & she started up nicely.
I put 2 heaters on it for a load of 2.9kw & ran it for over an hour.
Tested engine rpm unloaded 3720rpm, 1.5kw load 3600 rpm 2.9 kw load 3530rpm. Ran excellent. I put 2oz of marine 2 stroke oil in fuel & ran another 1/2 hr.
Diesels do store well but even they need a little love to stay healthy.
A word of caution here, fortunately the rack was stuck closed (off). If it was stuck open full throttle it could have been exciting. Always need to be ready to shut the air off or fuel supply with a diesel if it hasn’t been run recently to avoid serious damage/injury.

90cummins

 

[shanana]

Hello my friends and helpers, finally i found time to dissasemble the engine.
Here are the results

 

[ponytug]

Hello my friends and helpers, finally i found time to dissasemble the engine.
Here are the results

Congratulations on finding the cause! I hope that the rebuild goes quickly and smoothly.

All the best,

Peter

 

[90cummins]

I can’t say what caused your piston to break but starting fluid can certainly cause that.
Give it a quick hone & a new piston & rings and you’ll be good.
Is that a Yanmar or clone?
90cummins

 

[goeduck]

Speaking of starter fluid, I had a weird dream last night where someone was trying to get my Massey tractor to start with a fire extinguisher filled with starter fluid. He was hosing down the air intake. Even weirder was that I was the one on the Massey holding the key in start position.

 

[Keaton85]

Looking over this topic i could not find i formation about helping camshaft needle bearing wear.

This seems to be a common issue with these engines as pictured by others. What are some doing to mitigate the wear on the camshaft at the needle bearing?

I just stripped down one of these due to a dropped exhaust valve, and found significant wear on almost all bearing surfaces. The generator had only 325hrs.

 

[ponytug]

Looking over this topic i could not find i formation about helping camshaft needle bearing wear.

This seems to be a common issue with these engines as pictured by others. What are some doing to mitigate the wear on the camshaft at the needle bearing?

I just stripped down one of these due to a dropped exhaust valve, and found significant wear on almost all bearing surfaces. The generator had only 325hrs.

Welcome!

I'm afraid that as far as I know there isn't.

If you have a Chinese copy of the Yanmar engine, I think that at this point there is very little to be done to prevent wear due to soft bearing surfaces, beyond regular oil changes with good diesel oil. Bearing surface wear comes down to metal hardness, and oil, and I am assuming that you kept the oil level within specification. Technically, I guess you could machine out the old surface and press in harder metal, but I suspect for almost everyone it would be cheaper to go buy a Japanese Yanmar.

Enough people have found sand and metal in their first oil changes that I think the suggestion (@90cummins? up thread?) to fill a new machine with oil run it for a few minutes and drain and clean the filter and oil pan, and then refill is worthwhile. I ran the second oil change for 10 or so hours and drained it out of a concern for more debris, but I did not find anything visible in the second oil change.

All the best,

Peter

 

[90cummins]

Looking over this topic i could not find i formation about helping camshaft needle bearing wear.

This seems to be a common issue with these engines as pictured by others. What are some doing to mitigate the wear on the camshaft at the needle bearing?

I just stripped down one of these due to a dropped exhaust valve, and found significant wear on almost all bearing surfaces. The generator had only 325hrs.

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