186D delay relief valve rusted in place

[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.