186D delay relief valve rusted in place

[Yanmar CC]

I have been troubleshooting my problem shifting (trouble getting powershift to engage), have done all the easy stuff and have moved on to the delay relief valve. When I pulled the cover plate there was no o-ring seal behind the plate, not surprisingly I found rust behind the plate and when I went to pull the DRV sleeve out I found it is rusted in place.

Has anyone run into this before, if so, how did you get it free? I have tried a few squirts of PB Blaster and mild tapping to try and break it free but don't want to break something while trying to fix it. I currently have a small folded up piece of shop towel soaked in PB Blaster being held in place by the cover plate.

One thing comes to mind, can I just use a jam nut against the sleeve and try to spin the sleeve in place to break it free? I can't see very clearly in my service manual if there is anything indexed in side there that spinning the sleeve would break or bend.

Any guidance on this would be much appreciated.

 

[California]

I don't have an answer, but rather some related questions: I've always wondered how the shift delay works. Also, there seems to be a circuit that leaves a brake applied internally until the transmission has warmed up. Can anyone explain how these work?

 

[R Barger]

I have been troubleshooting my problem shifting (trouble getting powershift to engage), have done all the easy stuff and have moved on to the delay relief valve. When I pulled the cover plate there was no o-ring seal behind the plate, not surprisingly I found rust behind the plate and when I went to pull the DRV sleeve out I found it is rusted in place.

Has anyone run into this before, if so, how did you get it free? I have tried a few squirts of PB Blaster and mild tapping to try and break it free but don't want to break something while trying to fix it. I currently have a small folded up piece of shop towel soaked in PB Blaster being held in place by the cover plate.

One thing comes to mind, can I just use a jam nut against the sleeve and try to spin the sleeve in place to break it free? I can't see very clearly in my service manual if there is anything indexed in side there that spinning the sleeve would break or bend.

Any guidance on this would be much appreciated.

On my ym336d the valve had threads in the hole in the valve and you put a bolt in the threaded hole which gives you something to grab hold of. I used a large set of pliers and lightly tapped on them with a hammer. The valve has an oring on it to seal the bore.

 

[winston1]

Just looking at the parts drawing it would seem the main relief valve is just on the opposite side of the cover. I don't suppose they share the same cavity and could be tapped out from the other side. Probably not. :confused3:

 

[Yanmar CC]

On my ym336d the valve had threads in the hole in the valve and you put a bolt in the threaded hole which gives you something to grab hold of. I used a large set of pliers and lightly tapped on them with a hammer. The valve has an oring on it to seal the bore.

Mine has the same threaded hole. I scraped away most of the corrosion using a dental pick and tried tapping on a small wrench slipped behind the bolt head, also tried using a long flat head screwdriver to pry/push the wrench away from the housing to see if I could get the sleeve to even budge, but no luck...

I think it may be a matter of a crusted over o-ring that is just stuck in there and I am going to have to figure out a way to fab up a puller to be able to pull directly on the axis of the sleeve.

Just out of curiousity, when you took the cover plate off of yours, did you have any corrosion in there? I think once I get it to come out, on reassembly I will put a heavy coat of grease on the back side of the sleeve before I put the cover plate back on and hopefully prevent this from happening in the future.

 

[R Barger]

Yes there was quite a bit of corrosion. You might take small piece of flat steel and bore three holes large enough to slide over the bolt your screwing into the valve the use two threaded bolts w/nuts to pull it. Hope you understand what I'm saying.

 

[Yanmar CC]

Yes there was quite a bit of corrosion. You might take small piece of flat steel and bore three holes large enough to slide over the bolt your screwing into the valve the use two threaded bolts w/nuts to pull it. Hope you understand what I'm saying.

I understand what you're saying perfectly because that's exactly what I was planning on doing...a homemade puller. Now I just have to go hunt down a couple of M6 screws to use...

 

[Yanmar CC]

Okay, so if anyone else runs into this, I was able to use a stick of 3/8x3/4 aluminum with a 1/4" hole drilled in it and set up the stick to span the two cover bolt heads (to offset it from the face of the block) with the drilled hole centerer over the tapped hole in the sleeve. Put a long M6-1 screw with a nut on it through the hole in the bar and thread into the sleeve. Holding the head of the screw stationary use the nut to pull on the sleeve and with a couple of turns it's out...

Soooo...now I've got everything out but the main relief valve. Everything I could get out looked ok, no noticeable wear on parts or anything clogged.

Now I'm going to have to figure out a way to pull the main relief valve out of there and see if it's gunked up, not sure if I can just reach in there and try to grab it with some long needle nose pliers or what. Any suggestions on how to get it out of there? Should it be removed with the valve block still on the tractor, or should I just go ahead and remove the entire block?

 

[winston1]

Manual for the 226 indicates the valve should come out with the sleeve. I think the valve has a machined groove in it. Wonder if you could use a hook something like one of these to get in that groove and maybe pull it out. :confused3: 7 Piece Pick and Hook Set

 

[Yanmar CC]

Ahh, maybe I am missing something, is there another diamond shaped cover on the front of the shift valve block that will allow me to pull out the main relief valve from the opposite side of the delay valve? From the service manual, it looks like it all has to come out from the back side?

 

[winston1]

I asked that question is post #4. You are there, is there a cover? The parts manual shows the main relief valve on the opposite side but maybe just for viewing purposes only??

 

[Yanmar CC]

I asked that question is post #4. You are there, is there a cover? The parts manual shows the main relief valve on the opposite side but maybe just for viewing purposes only??

Sorry winston, when I read your post, I was thinking you were meaning the main valve (I think that's what it is called) that is across the valve block the other way not the main relief valve. I was confused when I read that as I hadn't gotten far enough in to understand what I was dealing with and was focused solely on getting the DRV out as I believed that to be my culprit. The diagram does seem to indicate that maybe it does come out, but I haven't been able to get back to tearing more parts off the tractor.

What I am also finding now is there were no shims between the delay relief valve and the spring. From what I can tell, they are supposed to be on the DRV side and not the main valve side and are needed to up the pressure on the shifting. I am beginning to wonder if not having any shims in there at all would cause this problem of not getting the transmission to engage? I can usually get it to engage, it just takes a lot of shifting between gears (throw it in reverse, then 1st/2nd/3rd, and back and forth until it starts to roll a little bit) once it grabs, it's good to go, but if I disengage the clutch, I'm back to square one...

Does anyone know the size of the shims (from what I can find they are .5mm thick but haven't found the ID/OD of the shims) and the number of shims that should be in there for a baseline to start with? The parts manual just points out where the shims go but doesn't say how many should be in there by design.

 

[R Barger]

t

Sorry winston, when I read your post, I was thinking you were meaning the main valve (I think that's what it is called) that is across the valve block the other way not the main relief valve. I was confused when I read that as I hadn't gotten far enough in to understand what I was dealing with and was focused solely on getting the DRV out as I believed that to be my culprit. The diagram does seem to indicate that maybe it does come out, but I haven't been able to get back to tearing more parts off the tractor.

What I am also finding now is there were no shims between the delay relief valve and the spring. From what I can tell, they are supposed to be on the DRV side and not the main valve side and are needed to up the pressure on the shifting. I am beginning to wonder if not having any shims in there at all would cause this problem of not getting the transmission to engage? I can usually get it to engage, it just takes a lot of shifting between gears (throw it in reverse, then 1st/2nd/3rd, and back and forth until it starts to roll a little bit) once it grabs, it's good to go, but if I disengage the clutch, I'm back to square one...

Does anyone know the size of the shims (from what I can find they are .5mm thick but haven't found the ID/OD of the shims) and the number of shims that should be in there for a baseline to start with? The parts manual just points out where the shims go but doesn't say how many should be in there by design.

My 336 has 3 shims. Your problem sounds very similar to the problem I had with mine. The valve was sticking on it. A good cleaning and it works as it should. At first the problem would come and go but it completely quit pulling.

 

[normde2001]

How long have you been having shift problems?

 

[Yanmar CC]

t

My 336 has 3 shims. Your problem sounds very similar to the problem I had with mine. The valve was sticking on it. A good cleaning and it works as it should. At first the problem would come and go but it completely quit pulling.

Thank you sir. Now I just have to get some time to tear it back apart and get some measurements so I can figure out what size shims I need to get my hands on...then I at least have a starting point to try it again and see if the shims fix the problem.

I was able to get the delay relief valve out and found no indications of anything clogged, so hopefully the shims might help. If removing them lowers the pressure to the clutch packs, I am hoping that not having any at all is the cause of my problem and can be an easy fix!

 

[Yanmar CC]

How long have you been having shift problems?

I just got the tractor about a month ago. I got it for what I thought was a pretty good deal ($4,250 for the tractor with a tandem axle trailer, brush hog, box blade, and tiller).

The shifting problem was a known issue when I bought it, and after researching the powershift issues/symptoms/fixes on this site, I decided to go ahead and go for it figuring I could fix the problem relatively easy. I still think it is something simple, because the problem is getting the transmission to engage, once it grabs, it goes no problem, it's just getting the transmission to grab a gear.

 

[winston1]

Amount of shims needed is determined by pressure. Pretty sure you have a port for hooking up a gage for testing.

 

[grainger12002]

I would think hoye or some of the other yanmar folks could set u up w some shims, maybe even make them up, but as stated it depends on how much you need ???

 

[normde2001]

You originally wrote you "have done all the easy stuff". Exactly what does that entail. You obviously have/had water throughout the system, and any or all valves could be rusted. I would check them out before worrying about shims. Does the 3ph work properly?

 

[Yanmar CC]

You originally wrote you "have done all the easy stuff". Exactly what does that entail. You obviously have/had water throughout the system, and any or all valves could be rusted. I would check them out before worrying about shims. Does the 3ph work properly?

There is no indication that there was water in the system. The rust was on the backside of the sleeve (not internal to the valve block), that part is unprotected from the elements as it is only covered up by an ungasketed metal cover plate.

Three point (and FEL) works flawlessly.

ON EDIT: The easy stuff entails drain and flush of fluid (replaced with correct UTF meeting JD303 spec), removal and examination of suction strainer, replacement of hydraulic spin on filter, and (now) removal and inspection of DRV for debris blocking flow of fluid to valve.