RK24 Hydraulic failure

[Fergenheimer]

Also, looking at the dead grass, the leak started a lot sooner than I realized it. So the blowout was not related to that sharp right turn.

 

[Fergenheimer]

I have an o-ring kit. The o-ring I used had the same id but had a 3mm cross section instead of a 2mm. I did not have the size that was in there.
I had not thought about a pilot line for the relief on that hole. I had guessed it was an orifice to limit flow if you did blow out. I did not get a good shot of the tip of the plug but the attached does show the seat for the ball that I mentioned above. I do not recall a lead in chamfer for the o-ring. I think it was just a flat surface.

 

[oldnslo]

I suspect faulty assembly on first O-ring or cavity plug screws into not machined correctly. Second failure could be similar problem if cavity not correct. That O-ring should fit into a machined chamfer approximately 12 - 15 degree angle. I have seen some where you could see the O-ring chamfer along the hex with the plug installed. If you can see the seal it will eventually blow out.

Wrong size seal can cause same problem since it will not squash into that chamfer and then get trapped between head of plug and body. Smaller the plug the more critical the O-ring size.

 

[oldnslo]

I see You posted 3 mm vs 2 mm cross section that could be a reason second seal failed see my previous post in attempt to explain why

 

[Fergenheimer]

When I get the block off again, I will try and get a picture. The one of the bottom of the block is before I removed the plug and you can see the original o-ring protruding from beneath the plug. Thanks for the help.

 

[Fergenheimer]

As a stop gap until I get a hydraulic test gauge, I'm going to limit my engine speed to 2500 rpm. My assumption is that the hydraulic pump is shaft driven and the faster it turns, the more flow since it is a positive displacement and thus more return flow or more pressure. Is this a good assumption. Full rated pto speed is 3000 rpm. I use a mid mounted pto driven finish mower so it would not be quite as fast.

 

[oldnslo]

Yes flow will increase with engine speed but pressure should have minimal increase from the increase in flow IF the relief valve is sized and working properly.