Oil & Fuel L48 leaking TDH fluid

[Murphyflyer]

A bad leak has started from the bottom of the hst and mid case joint. It is leaving a noticeable puddle in just a few minutes. Could it be a seal inside the hst? I am right in the middle of doing a septic field. Am I correct in thinking this requires a split to take the hst and mid case apart to investigate? I did check the torque on the bottom bolts of hst/mid case joint and they were tight. Any thoughts?

 

[rbargeron]

Two years ago there was a L48 gasket leak thread with pictures The member posting about it was also a new TBN member - jhiller18405 - and is a Kubota service guy in PA.

The machine has to be split to get access - not a small job, and sealing it up took several attempts.

 

[Murphyflyer]

Thanks rbargeron. I will look at the thread.

 

[rbargeron]

Sent you a private message - Dick B

 

[Murphyflyer]

I have started the split. Today the removal of the loader arms, brush guard, side brackets was done. I am now trying to remove the loader posts and the pins are really tight. I cannot make them move at all. Should I be thinking of heating the bushings with oxy/acetylene? Then apply the sledgehammer to the pin?

 

[rbargeron]

I wouldn't expect the pins to be that tight. Maybe the uprights are being bound up by other parts of the framework? They might free up by loosening the bolts connecting to the braces 170 and 220 (see attached pdf). Loose bolts will also help it go back together later. Good luck, Dick B.

 

[rScotty]

I wouldn't expect the pins to be that tight. Maybe the uprights are being bound up by other parts of the framework? They might free up by loosening the bolts connecting to the braces 170 and 220 (see attached pdf). Loose bolts will also help it go back together later. Good luck, Dick B.

That's exactly what I would try first. Remove everything from the upright - including every and all the braces and cylinders. Then you will be able use the leverage of the upright to rock it around those pins. That and some penetrating oil ought to loosen them up far more than any heat could do. My guess is they have some corrosion holding them in place. If so, rocking the upright and oil will do more than heat.

I've sometimes found it worth the time to make up a special pin puller or pusher to put constant pressure on a pin instead of beating on it. Judging by the other thread, this is going to be a long and involved job although not a particularly difficult one. But from that thread there is going to be a lot of emphasis on going slow and doing things in a careful manner - otherwise it just has to be done again. At least that's what I got from the other thread.
rScotty

 

[Murphyflyer]

Everything was removed from the uprights before I tried to remove the pins. The right side was the problem. I did apply penetrating oil and heat but the pins remained fast. So I left both uprights in place and continued to strip the fenders, floor boards etc. until I could drop the frame onto the floor.
Yesterday I split the tractor at the hst/midcase joint and removed the port block. The port block /hst gasket is were the leak is. I am going to the dealer tomorrow to look for parts.
Am I correct in thinking that the hst case is pressurized when running? Should I use Permatex along with the new gasket?
The back side of the port block doesn't have a gasket. They used a black silicone type of sealant for that joint. So perhaps the midcase is not under hydraulic pressure.

 

[rbargeron]

The HST housing does see a small amount of internal pressure. The HST has 5 relief valves. One of them, the case relief valve (part 22 on attached), vents case pressure into the mid case. The WSM does not give a pressure setting for it, but says "it opens and flows the oil directly to the transmission case, so that the oil may not leak against the sealings". This indicates a low relief pressure - to keep the HST free-flowing internally with little resistance.

One of the "sealings" the valve protects is the gasket that failed and now needs replacing. The WSM doesn't state the relief pressure or how to test it - but the valve should be checked for easy opening function. With wear the HST's normal internal component leak-by can increase in volume. With higher flow, a sticky or restricted relief valve could contribute to gasket or seal leakage.

In jhiller18405's case (post 2), the leaking gasket repair needed reworking twice - implicating not just insufficient gasket strength, but maybe a wear-related increase in operating pressure inside the case? Does your HST perform normally other than the oil leak? Dick B.

 

[Murphyflyer]

Yes it does operate normally. I will look at the check valve before reassembly.
Thanks,
Harry