Help needed - leaking hydraulics issue

[Soundguy]

If the 3pt piston travels too far, the oring can become pround outside the mouth of the cyls, it seems on some of the chinese units.. and then going back int he oring gets cut up. In any case.. of the oring leaves the cyl.. oil CAN bypass it. Where it goes? I don't have a jinma parts manual.. would have to look to see what sump excess bypassed oil goes into.. etc.

Soundguy

 

[GuglioLS]

The piston cannot “travel too far” this is just a rumor and perhaps a subliminal way of trying to trash Chinese tractors.

I removed the seat & the top of the TPH cover and examined it in operation first hand for myself. The o-ring at the end of the piston will not go past the end of the cylinder -mechanically it’s impossible. So don’t believe it. – What is happening is that the piston is TRYING to go to far – this is why the engine is straining when the THP is set all the way up. This would be something out of adjustment and needs to be corrected.

Second if there were a leak at the piston o-ring - fluid would leak back into the TPH reservoir not the tranny.

My theory is that one or more of the following was damaged by hauling butt with the Box Blade bouncing up & down.

Leak Down: (Pre Condition?)
Loose or broken spring on draft control or position control.
Spill valve dirty or damaged, o-ring in spill valve
Damaged TPH Piston or o-rings.
May have cracked the walls of the cylinder causing it to leak down.

Hydraulic Loss into tranny:
Loose or damaged cylinder mounting bolts between the TPH & top of Tranny.

The “Gizmo” on the back of the TPH is the feedback for draft control.

See the attached parts diagram there are 2 bolts & 2 studs holding the cylinder to the bottom of the TPH box, if they are damaged or loose the leak into the tranny could be there.

Not sure what you mean by the TPH box being upside down – please elaborate .

 

[GuglioLS]

Another Picture of the internals of the TPH

 

[GuglioLS]

Position & Draft controls

 

[Soundguy]

</font><font color="blue" class="small">( The piston cannot “travel too far” this is just a rumor and perhaps a subliminal way of trying to trash Chinese tractors )</font>

Hmm.. Looking in the archive, there are several threads that specifically mention this issue.

I havn't had a jinma 3pt cover off.. so can't say. I do know on ferguson system tractors, if the linkage is damaged, and the 'feeler' that sets at the mouth of the cyl is back to far, then the piston will push out too far and cause this kind of problem. The feeler , when it is moved by the piston just as tthe piston reached max designed travel, and is mover about 1/4 in by the piston, in turn turns off the intake valve on the pump, thuss stopping further oil from being pumped into the cyl. If oil leaks from the cyl.. the piston is forced back in the cyl under load, thus letting the feeler move back to rest position, thus opening the intake valve again to start a regeneration cycle, unless the operator moves the hytrol valve down manually, thus, again, shutting off the intake valve, and/or opening the exhaust valve to let the cyl down.. etc.

On quick search here are a few threads from this forum that mention the piston travel issue , and damaged seals resulting from that travel.

1st instance

2nd instance

3rd instance

4th instance

Ok.. I've searched back thru a few months.. there's 4 instances of mentioning over extended piston / seal damage...

4th instance - from ctoa

Just for kicks, here's one from CTOA....

Soundguy

 

[bluechip]

I havn't posted on the subject of this thread because I have not seen a Jinma 454 in person. All Jinmas are not the same and there are just too many times well meaning people give advice based on thier tractor, not realizing that the poster has a different series altogether. POint in fact, the lift box on 200 series (20-28HP) is different than 300 series. Some 200 series lift pistons can and have traveled past the cyl (at least the O ring. the adjustment that prevents this is external and easy and should be done at assembly. As Larry says, HIS 300 series cant do this, has a totally different design. the 200 does not have draft/position control at all. the 300 series jinma shares the same lift box design with our KAMA tractors, both TS and KM (sizes vary). We have never had this issue.

Now on this type of lift box there is a cover under the seat to access the cylinder and valve mechanism, but it sounds like the 454 does not have this?

I don't know for a fact that the resevoir is separtate on 400 series Jinmas but based on Eddies posts, it seems that it is and if so it must have a crack in the bottom part of the casting between the lift box and the rear diff housing. but since I have never seen a 454 Jinma apart it would be better if someone who has serviced some of these jumped in here. all I could offer was that if I was having this problem on a KAMA, it would have to be a crack/hole inthe bottom of the lift box casting or a blown seal on the rear mounted pump (which Eddie does not have) the cylinder would simply leak back into the lift box, undetected and without loss of fluid. I think the lift box needs to come off, Use an engine hoise, gantry or a couple strong guys, that thing is HEAVY.

 

[Soundguy]

</font><font color="blue" class="small">( I havn't posted on the subject of this thread because I have not seen a Jinma 454 in person. All Jinmas are not the same and there are just too many times well meaning people give advice based on thier tractor, not realizing that the poster has a different series altogether )</font>

Hey now there is some good advice. At least a couple of the instances in the previous posts i found, the advice being given was just a general 'watch out for this' type of situation.. not model specific.

We see here that there are very many model specific differences.

good post.

Soundguy

 

[ejtaylor822]

Hey guys,
Great dialog. I really appreciate everyone's input and discussion on this. Suffice it to say, that with this level of conversation, I am getting a little nervous. I am approaching this with an open mind and just want to figure out what is going on and get it repaired.

Didn't get home in time to tear into the case, but, was able to get some pics which I will be attaching in the following threads. Also, attaching the exploded parts diagram from the parts book.

Once again, appreciate everyone's help on this. I am fairly mechanical, but, when it comes to hydraulics - I am at a loss. I hope when I open the case up, it will be OBVIOUS what is going on - crack in the plate, blown O-ring, etc.

First attached pciture is the side of the case - right side as you are standing facing the front of the tractor. Notice the bolts through the bottom of the case into the axle housing. In the parts diagram that will be following you will see a plate on the bottom of the sump housing.

Thanks again,
Eddie

 

[ejtaylor822]

The attached view is looking at the front down the right side.

Larry,
This is what I meant by "being upside down". Looks like the bolts have to be removed and the entire housing flipped over to look inside. This is what I was referring too when I said it would be nice if there was a plate was on top, which could be removed, and could look down inside. Would really like to look inside when there is fluid in there to see any bubbles, drainage, etc.

 

[bluechip]

You may be able to pull the front cap of the cylinder off and see something, but I really think you will end up lifting the box off the tractor and looking underneith, This seems to be similar to the 200 series lift box in that it does not have a top cover plate, but you can remove the rear where the top link mounts and creats a pretty good size hole to look inside, what does the back of the lift box look like?