CK/HST - Transmission Leak

[Fuggley]

I have a small persistent hydro fluid leak where the mid-section piece is joined to the back transmission case. See diag.
I had the tractor split and repaired last year with a bunch of new internal o-rings, new case bolts and re-goop gasteted. The leak stopped for a few months but now is baaaack. I notice that it drips a lot less (less than a teaspoon every month or two) if I don't relieve hydraulic pressure on the bucket when I shut it off so I'm probably not going to have the tractor split again any time soon.
Any ideas what could cause this? I assume it's always got hydro fluid in this section so is it most likely just a bad gasket application? Could a leaky hydro pump seal cause this?


.... actually, the gasket weeping is more like along the bottom.

 

[mj007]

'less than a teaspoon every month or two' ......................... If that is all it's leaking, I would not worry about it, just keep the system full.

 

[Fuggley]

yes... makes sense, I agree. The last time this happened before I had it split I torqued up the bolts pretty good but it didn't help. I had new T-case bolts installed when they put it back together just in case I stretched them.
I'm looking at the torque specs before I try that again and I see they are rated at between 1 and 1.2 foot pounds.... sheesh... that seems light? Is this a misprint or am I just stupid again

 

[JoelD]

48nm is 35 ft-lb. checked the web for conversions.
Joel

 

[MinnesotaEric]

yes... makes sense, I agree. The last time this happened before I had it split I torqued up the bolts pretty good but it didn't help. I had new T-case bolts installed when they put it back together just in case I stretched them.
I'm looking at the torque specs before I try that again and I see they are rated at between 1 and 1.2 foot pounds.... sheesh... that seems light? Is this a misprint or am I just stupid again
View attachment 486081
View attachment 486082

That spec should be listed in inch pounds if it isn't a misprint. Inch pounds is most common in aviation applications, but transmission bits use inch pounds frequently as well. Consider calling for clarification.

 

[Fuggley]

Thanks Joel, converting Nm to get 35 ft-lb seems reasonable. I could use that. Eric, I may call Kioti about this before I re torque. Should I bottle-jack up the transmission a bit at the join before I re torque? I had no luck stopping the leak before the split last time.

 

[Fuggley]

Is there a transmission guy on this site? If I get a leak at the bottom/back of that mid section case, is it just related to the case sealant gasket? Or could it be an internal seal/o-ring? To me, that section should be wet internally anyway, so so can't see how an internal seal/o-ring could cause what I'm experiencing.
Anyone have an expert opinion on this?

 

[Fuggley]

It's a low priority to me and its weeping so little that I hope I may never have to open the transmission up.... but if anyone has ever taken that mId-to-back section of the transmission apart, I could use an opinion as to the source of the leak? Is it most likely just the transmission sealing goop or an internal seal causing this? Thanks.

 

[IslandTractor]

If it were me, the leak would have to get bad enough that I was adding more transmission fluid than what I spent on 50 hour oil changes before I'd even consider touching it. A quart every ten hours or so of operation would in my book just be another "operating expense".

 

[Rudevette]

There is a bobcat service bulletin for leaks in this area that results from the bolts stretching under torque conditions. Talk to a bobcat dealer or see if you can locate "knowledge article #000002611". I have heard of people retorquing their bolts multiple times and the keep loosening back up again until they are switched with the new hardware. Apparently it includes replacement bolt and washer part numbers as well as a procedure for replacement. I haven't seen it but would be interested to if you locate it. There has been good discussion on this in the bobcat tractors forum if you are able to dredge it up as well.

Justin

 

[BTI]

The "seal" for this is just a silicone. We typically split the unit, clean everything very well then reapply sealer and let it dry to a "heavy skin" then reassemble.
Doing this job "on the clock" is a real pain because the shafts do not like to line up LOL so extra time and care must be taken.
It is quite easy to mess it up reassembling because of this fact.
You also have to make sure ALL oil is out of the bottom of the 2 halves so that oil doesn't start to run forward while reassembling and ruin your seal.
I'm guessing the reason it leaks more when the bucket is up is because it causes the case to open up a very slight amount at the top.
If your seal is already leaking this slight amount would be enough to cause it to leak more when the bucket is up.

 

[Fuggley]

Yes, it's not a major issue. The tractor has been a real work horse.
I did have the transmission split and that section resealed at the 800 hour total hydro fluid change. If I'm still kicking at the 1600 hour mark I might get it done again it if I bothers me enough.
In the meantime I'll retorque the bolts and see if that helps. It also makes sense that there might be some bolt stretching going in there too as I've really lifted some really, really heavy stuff with it.
There is something to be said for an old dependable tractor with lots of battle scars and the odd drip going on. I think my CK is getting to that stage.

 

[rimshot]

Are you sure the culprit might not be one of thie hyidraulic filters. I have owned both a ck 20 and a ck 2510. Both tractors were prone to leak from thie hjyidraulic filter cans while the tractor was running. Just checking.

rimshot

 

[Alien]

There is a huge difference between Ft-lbs and lbs-ft

 

[Fuggley]

true...

 

[Alien]

Fuggley, have you ever had a Injector pump problem? Just curious as you have done quite a few hours now.

 

[Fuggley]

Yes, the IP broke between 400-500 hours. It was the typical cheap brittle gear teeth problem. I replaced it with a new one myself.... the install was easy. Richeyvs has it recorded on his spreadsheet.

 

[Alien]

Thanks Fuggley.... just what I wanted to hear. Mine is due to go then....

 

[Fuggley]

wondering.... has anyone ever used this spray goo to slow up a transmission gasket leak? Any chance this stuff might actually work? I'm going to pick some up sometime if I can find some... it doesn't seem to be a standard stock item in auto supply stores.
https://www.permatex.com/wp-content/uploads/2016/02/82099.jpg

 

[VictorW]

It does seem hard to find because out of stock but found it here. Amazon.com: Permatex 82099 Spray Sealant, 9 oz.: Automotive

The reviews are mixed as to how good it works.