YM226D Project

[tc197]

Pulled the injectors back out this afternoon and attempted to check the compression. I am getting 280psi on the cylinder furthest forward and 250psi on the middle and rear cylinders. According to my service manual, 426 is considered the low where it becomes hard to start so that may explain part of my struggles. Could I be doing something incorrect when checking compression that would give a lower result or is it pretty black and white and I need to look into an overhaul/rebuild?

I checked the rods and linkages the other day and didn't see any issues. I attempted to look at the governor mechanism but apparently I am missing a section in my manual and it wasn't clear to me what to check so I left it alone for now. Now that the injectors are out again, I will test the spray patterns when I get a chance.

 

[winston1]

About a 300 rpm speed is needed for compression check. A good starter and battery should provide that. Probably did but might pull all three injectors while checking one cylinder at a time.

 

[CoyPatton]

I second Winston’s suggestion of pull all 3 injectors (label them in a manner that you know what cylinder they came from for diagnostic purposes) then rerun your compression test. A slow turning engine is often difficult to start.
This is one of the reasons that most import Yanmars have a decompression lever on them.
Prior to tear down, I would spend more time in assessment of what is going on. Bore scopes can provide lots of info without removing the head from the engine. Also check the valve clearances.

 

[bmaverick]

I second Winston’s suggestion of pull all 3 injectors (label them in a manner that you know what cylinder they came from for diagnostic purposes) then rerun your compression test. A slow turning engine is often difficult to start.
This is one of the reasons that most import Yanmars have a decompression lever on them.
Prior to tear down, I would spend more time in assessment of what is going on. Bore scopes can provide lots of info without removing the head from the engine. Also check the valve clearances.

Coy, You are so right. I've made it a full habit to PULL the decompression cable no matter what season to start the engine. The less hard starts the longer engine life.

In fact, I used that decompression cable so much, the plastic mount to the dash panel broke. I've posted here how I remedied the fix.

Hope to hear from tc197 soon!

 

[tc197]

Just to be clear I'm doing this right:
- Disconnect fuel lines and fuel return lines
- Pull all 3 injectors (label/keep track of which cylinder they go in)
- Insert Hoye compression adapter in place of injector. I am placing the adapter on top of the fiber washer and holding it centered while I secure it in place with the injector retainer. The adapter is a smaller diameter than the injector.
- Connect compression gage and place throttle in full rearward (off) position.
- Crank the engine over, ideally looking for 300rpm and record compression reading. Should I be using the decompression lever in my compression test to get the speed up, or are you strictly mentioning that for starting purposes?

On a side note, I tested the injector spray patterns this morning and all three look pretty good in my opinion. I held some cardboard about 3 inches away and all three sprayed about a 1" circle of fuel onto the cardboard.

Thanks for the help guys, really appreciate it!

 

[runningbird]

don't pull the decompression lever for the test

 

[tc197]

don't pull the decompression lever for the test

Thanks runningbird.

Using the process I just mentioned above, with no decompression lever, my results were 305psi, 250psi, 255psi.

I have not checked valve clearances before - on this tractor or in general - so I will go read up on that process. Thanks CoyPatton.

 

[tc197]

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Seems pretty straight forward, I'll give it a go

 

[tc197]

Valves didn’t appear to be way off, although I’m not sure how much they would need to be off in order to notice a difference. Regardless, I adjusted them all to .007-.008 using a feeler gauge set and followed the process in the procedure linked above.

I rechecked compression after playing with valves and got the same results.

We have a lot of rain coming tomorrow so I wanted to button things back up. While I was putting the injectors in I must have overtightened the retainer and ended up cracking one and causing a small split in another. Lesson learned and I’ll have to find some replacement retainers.

 

[winston1]

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All States Ag Parts is the leading supplier of tractor, combine, and skid steer parts to North America. Shop for new aftermarket, remanufactured, and used tractor parts.

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