L3400 Hydro Leak found, advice on fixing

vulcancowboy · Jul 11, 2017

So, I think I finally found the source of my hydro leak. Initially thought it was coming from the vent under the seat, but upon further exploration it appears to be coming from the joint where the hydraulic case cover is bolted onto the transmission (see breakdown).

My question is what type of sealant should I use to seal this connection? Something like Kubota: Acid-Free Grey Silicone Gasket, Part # 07935-60074? Kind of expensive at $44 per tube, but if that is the best choice, I'll spring for it.

Any advice/recommendations appreciated!

ccsial · Jul 11, 2017

When I first got my L3400 HST, 2005, the dealer replaced the 3 pt valve with one that does not jerk. They sealed it with the grey silicone stuff and it is still fine.

teg · Jul 11, 2017

ccsial said:
When I first got my L3400 HST, 2005, the dealer replaced the 3 pt valve with one that does not jerk. They sealed it with the grey silicone stuff and it is still fine.

Ditto, with everything he said. ^^^

vulcancowboy · Jul 11, 2017

ccsial said:
When I first got my L3400 HST, 2005, the dealer replaced the 3 pt valve with one that does not jerk. They sealed it with the grey silicone stuff and it is still fine.

Would the Permatex Ultra Grey work, or should I get the Kubota product?

ccsial · Jul 11, 2017

I don't know enough to answer that. If it was me I'd use the Kubota product. Maybe someone smarter about this will answer.

David_Kb7uns · Jul 12, 2017

Use the Kubota stuff.

The Kubota product is Three Bond TB1200GAU3Z

ThreeBond - Silicone Gasket | eBay

WPS has it in their catalog also.

Works good used it when I replaced the brake case on the L3130 and by the time I got everything torqued down filled with oil and no problems on cure time.

David