Forum for air cooled diesel engines and clones

[90cummins]

Here is the Yanmar timing procedure






90cummins

 

[Ilikeurtractor]

I don't own a leaf blower but I suppose a shop vac blower side would be similar. I think I'll just wait until I can take it to a lower elevation (which is cheap too since I'm going there anyway) and test it. Thanks for the suggestion though.

Hmmm. I guess I was supposed to run my engines up around 3200 rpm and check for missing at a lower elevation. I can do that now, and I will as soon as I get a chance. Good thing I wrote a "note to self" back then. LOL So much for the good memory I thought I had!

 

[Ilikeurtractor]

Ran the Yanmar L40A up and was able to achieve 3600 rpm at 800' asl (vs. 3200 rpm at 6200' asl) without missing but it did start missing as I tried to apply more fuel above that speed. So although I don't think air pressure is the root cause of the problem it does have an affect at what speed this occurs. I realize this doesn't really solve anything but at least provides another data point and indicates more of a breathing issue vs. some of the other possibilities in my opinion.

 

[OldRedTractors]

Thanks 90cummins! I think I found my mistake - I made an error with re-assembly of #10 in your drawing, which doesn't detail the pressure valve assembly, or whatever it's called. Obvious once I looked at it again of course.

View attachment 548258View attachment 548259

I had it flipped the wrong way - the inner valve assembly where the awl is pointing. It will go together wrong quite easily if you're not paying attention to how it's supposed to work... looks like no harm done, so one more try tomorrow!

Finally got back on it today. Re-assembled with my original injection pump, and it fired right up, with exactly the same behavior. I bypassed the fuel shut-off with a jumper wire - eliminating that as a potential problem - and no change. So oil pressure or electrical issues with the fuel solenoid is clearly ruled-out.

I had ordered a replacement injection pump (~$35) figuring it would be worth trying, so I then installed the new pump (didn't do anything with the timing check yet). It fired right up and ran a bit differently, although still crappy at high speeds. Here is the video of it running with the new pump:

Gen run 3 - YouTube

Main difference is it doesn't seem to be shooting flames out the exhaust anymore, so perhaps something is timing related, but I don't understand how that would cause the surging. What's baffling is that it fires up so easily and quickly that I have a hard time believing that there are any serious issues with the valves.

I'm about done with it at this point. I may get motivated to check the valve clearance, but my interest in working on it any longer is rapidly going to zero and I'll likely just scrap the whole mess and order a Kubota!

 

[OldRedTractors]

One last check - I pulled the valve cover and checked the valve clearances - absolutely no problem there. Clearances are correct and everything looks clean and correct. I assume at this point it's a timing issue with the cam. I give up - hate to admit I'm beat, but it's just not worth screwing around with this pile of junk any more. Even if I did get it running right, I still would need to trouble-shoot the generator side. So I ordered a new Kubota, should be here in a week or two, and have scrapped this one for $100 to someone with more patience and time than me... Anyone want a great deal on a brand new injection pump and AVR? PM me if interested, they don't do me any good at this point.

 

[Ilikeurtractor]

Sorry to hear. Sometimes it's best to cut your losses. I'm fighting problems with a kinetic log splitter. Getting a lot of advice not to bother with it. Probably good advice. It's unfortunate consumers pay the price of having to deal with poorly designed products even with the best intentions of keeping them going. I'm sure your new unit will allow to spend your time elsewhere.

 

[xp190]

Would anyone happen to have a wiring diagram for one of these gensets?
Im putting mine back together (still) and although all the connectors really only go one way, I like to double check everything before I turn it on.

xp

 

[JPinnell]

So I have a question regarding timing and compression. I bought an in-op "somewhat" disassembled generator with a clone engine from a guy who new nothing about diesels who bought it from an auction. I could smell a little ether when i picked it up out of his driveway for $100. I mainly wanted the motor, but everything appears to be there, so if I can get the motor going I will worry about the rest. After a couple of evenings messing with it I have the generator parts stripped off, oil changed and no chips/debris, checked valve clearances, freed up the plunger in the pump and have bled the fuel lines. I found a label for Changfa, which is a decent maker of these clones. Oil in the bottom of the frame, so its at least been changed once. There was a sticker that said "next service at 140hrs" and overall it appears to have seen little use so I'm hopeful.

I can turn the engine over by hand using the fan (no recoil) and can roll it though the compression stroke with a little effort. Should it be harder to do? The electric starter lugs a little on the compression stroke.

With the intake/exhaust extra removed I see a serious puff coming out of the exhaust (which feels warmer than ambient temp) and a little wisp out of the intake. This means the injector is firing. Does the wisp out of the intake mean timing issues? I only found 1 copper shim under the pump and I put it back in place.

At this point I guess I need to pull the head, check valves, piston rings, etc for carbon? I'm concerned too much ether cracked a ring.

Any other ideas??

 

[90cummins]

You shouldn't be able to roll it thru compression, that's an indication of low compression.
As for the starter lugging a little on compression that's normal for a clone engine.
The starters are not nearly as powerful as the OEM Yanmar starters, actually they are quite weak and an engine in good mechanical condition frequently will not make it over the first compression stroke if the engine stops close to the compression event. Typically you may need to bump the starter a couple times get the engine rocking before it will follow thru.
Does the puff have a diesel smell if so yes the injector is firing but the puff coming out the intake is not normal the valves need attention.
The either smell is a sign the owner tried to compensate for mechanical issues to get it started.
My first move would be to remove the head and check the valves then the piston/cylinder.
And let your observations be your guide.
These engines are not difficult to R&R, it would be a good learning project. Parts are not that expensive and are available on ebay.
Last year I repaired one of these gensets because it was running poorly.
Valves were leaking and cylinder glazed. Cut new valve seats, honed & replaced rings and she ran fine.
90Cummins

 

[JPinnell]

You shouldn't be able to roll it thru compression, that's an indication of low compression.
As for the starter lugging a little on compression that's normal for a clone engine.
The starters are not nearly as powerful as the OEM Yanmar starters, actually they are quite weak and an engine in good mechanical condition frequently will not make it over the first compression stroke if the engine stops close to the compression event. Typically you may need to bump the starter a couple times get the engine rocking before it will follow thru.
Does the puff have a diesel smell if so yes the injector is firing but the puff coming out the intake is not normal the valves need attention.
The either smell is a sign the owner tried to compensate for mechanical issues to get it started.
My first move would be to remove the head and check the valves then the piston/cylinder.
And let your observations be your guide.
These engines are not difficult to R&R, it would be a good learning project. Parts are not that expensive and are available on ebay.
Last year I repaired one of these gensets because it was running poorly.
Valves were leaking and cylinder glazed. Cut new valve seats, honed & replaced rings and she ran fine.
90Cummins

I pulled the head, cycled the valves, but did not actually remove the valves, etc. They looked normal, I was expecting a chunk of carbon or something under the intake valve. I may pull them and do a quick lap.

While the head was pulled I hooked the injector up and bled it. It and the pump are now firing. I only had one shim under the pump. Next step is to pull the front cover and check the flywheel marks and try to verify the timing is correct.

I ordered new rings and a gasket set. Sounds like I will be pulling the rod, piston, etc and doing a hone job.

I put new jugs and such on a VW air-cooled 25yrs ago. Been awhile since I've been this far inside a motor. Have to buy a ring compressor and hone.

Do the electronic side of these generators hold up over time? AVR, caps, etc? (I did read all 42 pages, but some of the info is yrs old) I'm only $200 into it so far. I really only wanted the motor, BUT since I'm this far into it, a running 6000W generator would be handy.