Hydro-Gear Input Seal Leak Cause?

[busdoctor]

I have a hydro-gear BDP-10 pump on an Exmark Lazer Z mower. Bought used a few years ago, always had some hydraulic noise but ran good.
Recently lost an input seal on the pump. I replaced the seal and ran good for a few hours until the seal let go again. The seal is not failing from wear but it looks like high internal case pressure bulging the seal out.
I'm wondering if the charge relief valve isn't opening, but it is only a ball and spring not a pilot valve. Does anyone have any experience with this seal being over pressurized from the case drain? I didn't physically check but the case drain line from the reservoir did drain back when disconnected so I don't think a blocked line is the cause but I will check it definitively.
Any thoughts appreciated.

 

[AKKAMAAN]

I have a hydro-gear BDP-10 pump on an Exmark Lazer Z mower. Bought used a few years ago, always had some hydraulic noise but ran good.
Recently lost an input seal on the pump. I replaced the seal and ran good for a few hours until the seal let go again. The seal is not failing from wear but it looks like high internal case pressure bulging the seal out.
I'm wondering if the charge relief valve isn't opening, but it is only a ball and spring not a pilot valve. Does anyone have any experience with this seal being over pressurized from the case drain? I didn't physically check but the case drain line from the reservoir did drain back when disconnected so I don't think a blocked line is the cause but I will check it definitively.
Any thoughts appreciated.

You are right the case pressure is to high. I do not know any about that particular pump, but most units with a "case", will have a case drain hose that drains excessive leakage back to tank. If case pressure start increases could be an indication that pump is worned out (increased internal leakage into the casing). But it could also be as simple as a kink (or another restriction) on/in the case drain line