Yanmar Vio 27-3 Blade drop.

Hello, I purchased this Vio 27-3 and it's had to so far have a whole track frame re-welded and completely rebuilt. (was in salt water in it's early life) That's fixed now. I have an issue with the blade currently which drops when the control handle is in the middle. The blade doesn't hold like it should. It will drop like it's losing pressure. I wondered if this was the cylinder but it's not. The Blade will stay up if the control handle is pulled all the way back, but it won't hold anywhere in the middle, it either drops to ground or stays all the way up, there is no middle positioning for the blade like there should be.

The blade cylinder has been confirmed good by technician. He believes it's the Spool Assembly, Blade section of the control valve. He's adjusted the spring etc with no change so he doesn't believe it's the cable or linkage. but the blade section of the control valve.

I called Yanmar for part 172457-74260, 172457-74270 or 172457-74300, and they stated no more parts exist. It seems silly to have to toss a perfectly good excavator because I cannot procure one part. Anyone know of a part that may work with this from a similar model Yanmar? Yanmar themselves cannot legally tell me they've stated. I found a part for a Yanmar Vio 20-3 which looks like it could work potentially. 172458-74750.

I would like to know if there are any other aftermarket replacements for this blade section, used parts for this section (in working condition), a similar part from another machine that would work, or any place I can find a new part. I need options, anything you can think of, even if it's expensive. I'm new to this kind of stuff and tried looking on the internet for these part numbers but have had no luck. Nobody I can find seems to sell them, but that may only mean I suck at searching.

Attached is the pic for my actual Vio 27-3 parts manual. Highlighted in Yellow are my part numbers, and the part I need a replacement for. Again, i'm looking for ANY solution, and don't really care about legalities, just need something that will work.

Thanks for your help.

Well, the spool could be suspect, but...
A) will the blade lift the machine and hold it up?
II) if you raise the blade and hold it upward, and shut off machine, will it stay up?
3) are you sure that the cable is neutral when the valve is neutral?
d) has anyone put gauges on the up and down circuits and verified that the relief valve isn't opening early?
V) since the blade hydraulics must go through the swivel (center rotary joint), could the joint be leaking internal?
f) how was the cylinder packing ruled out?

Unless you see debris on the hydraulic return filter pleats, I'm inclined to NOT blame the spool until the normal faults are ruled out.

@heymccall

A) will the blade lift the machine and hold it up?
Answer: Yes.

II) if you raise the blade and hold it upward, and shut off machine, will it stay up?
Answer: Yes

3) are you sure that the cable is neutral when the valve is neutral?
Answer: Yes according to the tech. (not self verified)

d) has anyone put gauges on the up and down circuits and verified that the relief valve isn't opening early?
Answer: Unsure if this was tried or not. Can you link me a guage tool I can purchase. I'd be willing to try this out myself.

V) since the blade hydraulics must go through the swivel (center rotary joint), could the joint be leaking internal?
Answer: I'm sure this is not leaking, at least visibly on the outside. The machine was recently removed with all lower hydraulics disconnected due to having the track frame rebuilt, and no leaks were found. It had to be reassembled and they would have also checked this part for leakage at that time. (Blade issue was there before this work took place) Also I had this guy inspect the machine over and didn't find any issue with this part.

f) how was the cylinder packing ruled out?
Answer: I had them remove the cylinder and verify it by eye and test. They tested the cylinder off the machine and it was holding in pressure testing. They also just repaired another cylinder for the bucket quick release and fixed those seals.

Thanks for assistance on this.

Ok, so, if the blade stays up, machine off, then the spool internals aren't suspect (scored bore, etc.).
The problem is most likely that the spool itself isn't centered when releasing the blade control.

Disconnect the blade control cable and make your own control (vise grips, heavy wire, etc..) and actuate the spool, raising the blade, and let spool return to center. If blade still falls, you'll have to check the centering spring retainer.

The arrow points to the threaded spring retainer that threads into the circled spool end.
If you remove cover 17, you're going to, most likely, find the retainer, that the arrow is pointing to, has likely partially unthreaded, allowing the spool to remain off center.

heymccall said:

Ok, so, if the blade stays up, machine off, then the spool internals aren't suspect (scored bore, etc.).
The problem is most likely that the spool itself isn't centered when releasing the blade control.

Disconnect the blade control cable and make your own control (vise grips, heavy wire, etc..) and actuate the spool, raising the blade, and let spool return to center. If blade still falls, you'll have to check the centering spring retainer.

The arrow points to the threaded spring retainer that threads into the circled spool end.
If you remove cover 17, you're going to, most likely, find the retainer, that the arrow is pointing to, has likely partially unthreaded, allowing the spool to remain off center.

Click to expand...

Excellent support Heymccall compliments on troubleshooting
Regards
Uffex