# Oil pressure in hydraulic/transmission case



## ThePFJ (Jun 29, 2021)

Hi all,

I'm a tractor newbie so apologies if this has an obvious answer. I have a Yanmar ke140 compact tractor, which from what I can tell are similar if not the same as some John Deere compact tractors.

I recently noticed an oil leak from around the transmission area, and when I opened the oil filler cap, oil came gushing out as if under pressure. I removed and cleaned the breather at the top of the transmission in case it was blocked but it wasn't. What I've found is that raising the hitch is OK, but whenever I lower the hitch the oil level is visible from the filler rises a little each time, until it eventually overflows. Raising the hitch doesn't seem to affect the oil level - only when the hitch is lowered.

Like I said I'm new to tractors so have no idea what could be the cause or even where to start investigating. Any thoughts / suggestions much appreciated.


----------



## BigT (Sep 15, 2014)

Howdy PFJ, welcome to the forum.

We have some very good Yanmar people visit this forum, so please standby... I have seen similar problems with some other tractors. In those cases, there was a baffle between transmission and rear differential section, with an equalizing port in the baffle. The equalizing port becomes blocked and fluid level builds in the transmission.


----------



## winston (Aug 19, 2008)

You have a transmission dip stick up toward the front right for checking fluid level. Have you checked it and got the level correct? Maybe just to much in there? Fluid look to be in good condition? Here is your parts manual.


----------



## ThePFJ (Jun 29, 2021)

Hi, thanks for your replies, and for the parts manual!

I did a complete oil change a few months back as the power steering RAM cylinder was leaking and had to be replaced, so while I was at it I drained and replaced the oil. I have a user manual which exaplined that there are three drain plugs, and I was extra careful to make sure I put the right amount of oil (7 liters if I remember). Has only had about 50 hours of use since but oil still looks OK.

Could a blocked oil filter/strainer be the cause? I hadn't replaced it when I changed the oil - not sure if it's possible to clean or whether it has to be replaced, like oil filters in cars.

Apart from that, the only other thing I did recenetly was adjust the knob under the seat which regulates how fast or slow the hitch is raised (don't know what it's actually called). Only mentioning it as it's located just above where the dipstick is and where the oil is being pushed out.


----------



## winston (Aug 19, 2008)

the internal screen shown in figure 35 should be cleaned at time of fluid change although I don't know what that could have to do with fluid overflowing.


----------



## ThePFJ (Jun 29, 2021)

winston said:


> the internal screen shown in figure 35 should be cleaned at time of fluid change although I don't know what that could have to do with fluid overflowing.


Giving it a clean won't hurt I suppose, but have to drain it again


----------



## bmaverick (Feb 20, 2014)

ThePFJ said:


> Giving it a clean won't hurt I suppose, but have to drain it again


Just use CLEAN 20L buckets so as to re-use the fluid.  

And what fluid did you put in the machine or known? For the Yanmars, TF500A is the fluid to use. And the John Deere J20C is the same stuff. 

Being elsewhere other than the USA, these 2 brands may be hard to acquire. In the eastern EU, Fiat/Mopar ATF+4 is used as a substitute as it closely matches. 

These 3 brands should have less ability to expand when under a working load. All are a synthetic formula. All had to ensure seals remain intact.


----------



## ThePFJ (Jun 29, 2021)

bmaverick said:


> Just use CLEAN 20L buckets so as to re-use the fluid.
> 
> And what fluid did you put in the machine or known? For the Yanmars, TF500A is the fluid to use. And the John Deere J20C is the same stuff.
> 
> ...


The user manual I have does mention TF500A, but I'm in France and I couldn't find that anywhere for love nor money.

I used Shell Spirax S4 TX 10W40. Just had a look at its specs and it has John Deere JDM J27 but not J20C. How different are those oils?

I just assumed a decent quality MF oil would be OK.


----------



## bmaverick (Feb 20, 2014)

ThePFJ said:


> The user manual I have does mention TF500A, but I'm in France and I couldn't find that anywhere for love nor money.
> 
> I used Shell Spirax S4 TX 10W40. Just had a look at its specs and it has John Deere JDM J27 but not J20C. How different are those oils?
> 
> I just assumed a decent quality MF oil would be OK.


The 10W40 is thicker meeting the J27 spec over the J20C. The J27 spec is for CVT and HST machines. Not at all for PowerShift machines. Being a thicker oil, the 3PT would move slower and difficulty in colder weather.

Can you find J20C in France? 

Yanmar TF500A is not easy to find in the USA either. I once located the TF500A in Kentucky from a large Fleet-n-Farm store that also sold Yanmar tractors. Otherwise, I have not seen anything else. 

The John Deere J20C is easy to locate and find at many stores. Depending on store location, Walmart offers it too. LOL

J20C base oil is 10W30

J20D base oil is 5W30 winter












































Yanmar and John Deere worked diligently for a hydraulic fluid to work in the compact tractors Yanmar makes for John Deere. It started back in the YM Series and carried thru to the present day. It began with J14, J20A, J20B and the present being J20C & J20D.

J20C & J20D are more than the base oils. There are friction modifiers, certain molecular chains to not stress at high temps, and lube modifiers to keep seals from swelling.


----------



## ThePFJ (Jun 29, 2021)

bmaverick said:


> The 10W40 is thicker meeting the J27 spec over the J20C. The J27 spec is for CVT and HST machines. Not at all for PowerShift machines. Being a thicker oil, the 3PT would move slower and difficulty in colder weather.
> 
> Can you find J20C in France?
> 
> ...


Thanks a lot for all that !

Yes, just did a quick google and there are some J20C oils here, hy-gard too.

So I guess first thing to be done is to put the right oil in it, clean up the strainer this time while I'm at it, and take it from there..


----------



## SidecarFlip (Mar 25, 2021)

I was thinking that Hy-Guard should be available worldwide as JD is an International company. Myself, I don't use it but I do pay attention to the viscosity index on any oil I do use.


----------



## ThePFJ (Jun 29, 2021)

SidecarFlip said:


> I was thinking that Hy-Guard should be available worldwide as JD is an International company. Myself, I don't use it but I do pay attention to the viscosity index on any oil I do use.


Hy-Gard is available here in France, so possibly it is available everywhere. All I had to go by was Yanmar TF500A and I couldn't find any oils which said that they conform to that spec. There are loads that say they conform to J20C, so now I know it's the same stuff there are plenty to choose from!


----------



## bmaverick (Feb 20, 2014)

ThePFJ said:


> Hy-Gard is available here in France, so possibly it is available everywhere. All I had to go by was Yanmar TF500A and I couldn't find any oils which said that they conform to that spec. There are loads that say they conform to J20C, so now I know it's the same stuff there are plenty to choose from!


Bravo!


----------



## ThePFJ (Jun 29, 2021)

UPDATE:

Found some J20C oil and flushed the transmission and also cleaned the oil strainer this time while I was at it.

Put the tractor to work for a few hours and the problem is still there - oil level rising gradually. Almost as if there's an internal blockage preventing the oil from flowing back to where it should be.

So back to square one..


----------



## SidecarFlip (Mar 25, 2021)

Sure the 'leakage is oil and not diesel?


----------



## ThePFJ (Jun 29, 2021)

SidecarFlip said:


> Sure the 'leakage is oil and not diesel?


Definitely transmission oil.
And the oil level rises a little only when the hitch is lifted and lowered - running the PTO isn't a problem.


----------



## SidecarFlip (Mar 25, 2021)

I have to ask, where is the case vent and is the vent blocked with something like a mud dauber nest? All cases will have some sort of vent. On my Kubota's, the vent is on top of the case, a rubber hose with a 'U' bend in it. I put steel wool in the end to keep 'pests' from plugging it as it's hard to access.


----------



## ThePFJ (Jun 29, 2021)

SidecarFlip said:


> I have to ask, where is the case vent and is the vent blocked with something like a mud dauber nest? All cases will have some sort of vent. On my Kubota's, the vent is on top of the case, a rubber hose with a 'U' bend in it. I put steel wool in the end to keep 'pests' from plugging it as it's hard to access.


Hi, the vent is on the top of the case towards the rear - it's an approx 6in rubber hose with a 3in plastic 'U' bend which bolts to the side of the case (on page 73 in the parts catalog I was sent above, it is attached to the breather pipe numbered 8). Needed to take the seat off to get to it. It wasn't blocked but I removed it anyway and cleaned it thoroughly with petrol and blasted it with compressed air.


----------



## SidecarFlip (Mar 25, 2021)

Is it blocked where it enters the case (fitting)?


----------



## ThePFJ (Jun 29, 2021)

SidecarFlip said:


> Is it blocked where it enters the case (fitting)?


No, it's not. I wasn't sure if I'd checked it first time round so went out this morning a blew some air through it.


----------



## ThePFJ (Jun 29, 2021)

Not having much luck at all with this 

I've had two farmer neighbours (who know a thing or two about tractors) look at it and they were both equally stumped. So I've resorted to going through the parts catalog page by page to try to find some clues as to what might be causing this!

On top of the hydraulics housing I can see that there are two valves - one safety valve and one relief valve. Any chance a faulty one of these could cause the symptoms I'm seeing?


----------



## SidecarFlip (Mar 25, 2021)

Relief valve plugged maybe? Clean it out and see what transpires.


----------



## ThePFJ (Jun 29, 2021)

SOLVED!

Don't mean to bump an old thread, but I found the problem I was having a while back so thought I'd post it here in case anyone else experiences something similar.

Turned out to be the oil seal in the hydraulic pump (labelled 2D in fig.9 in the parts catalog winston sent earlier on in this thread). The seal was blown so engine oil was gradually being pushed into the hydraulic circuit until it overflowed.

The thing was that the engine is burning oil anyway (probably a valve/piston ring that I haven't got round to sorting yet) so I attributed the fact that I was having to top up engine oil to that. One more lesson in what happens when making assumptions 

Nevertheless, thanks to all for your help


----------



## winston (Aug 19, 2008)

That is a new one on me. Are you sure your crankcase vent is not plugged?


----------



## ThePFJ (Jun 29, 2021)

winston said:


> That is a new one on me. Are you sure your crankcase vent is not plugged?


100% sure. In fact that's how I found it - I blew some compressed air through the crankcase vent (gently!) to make sure it was clear and I could hear a gurgling sound at the hydraulic pump and from inside the gearbox. 
Tried it again after replacing the seal and no gurgling sound, and the gear oil level has remained the same after several hours of use.


----------

