97 GTX oil in the rear cylinder

[shamrock246]

I test fired the ski after I changed the voltage regulator a couple of weeks ago and everything was fine. I went to take out this week and found the engine hydro locked with a lot of oil in the rear cylinder. I understand that this usually comes from the crank seals for the rotary valve cavity but the engine only has about 12 hours on it after a full rebuild and the crank was built by a reputable builder. I haven’t pressure checked the cavity yet, could this be caused by something else like a clogged tank vent? Why so sudden? Will the shut of valve do the trick? The valve shuts off the tank what about the return hose going back to the top of the tank will that drain into the crank case causing the same issue?

 

[burtshaver2021]

I think it could also be the check valve on the banjo fitting for the small oil lines

 

[dougamclean]

Get the pressure tester and check for leakdown...since basically the only reason to have that much oil in the cylinder is that it came up on the downstroke from the bottom of the crankcase.

Why prolong your suffering..just pull the bandaid off!!

I know you don't want to contemplate it..but it's gotta be done!!

 

[shamrock246]

I think it could also be the check valve on the banjo fitting for the small oil lines

Are there check valves at the pump end? I thought there were just check valves in the nozzle that’s in the intake port. The vent on the oil level sensor lets air in to the tank but not out, I think that is working correctly.

 

[shamrock246]

Get the pressure tester and check for leakdown...since basically the only reason to have that much oil in the cylinder is that it came up on the downstroke from the bottom of the crankcase.

Why prolong your suffering..just pull the bandaid off!!

I know you don't want to contemplate it..but it's gotta be done!!

I pressured tested it today with 5 psi it took about 45 min to loose 1psi. When I built the engine I put 5psi on it for about 5 min and didn’t see any drop so I continued assembling the engine,so it still looks the same as when I built it. The manual doesn’t give a time frame or leak rate so I guess it’s pointing to something else.

 

[burtshaver2021]

Are there check valves at the pump end? I thought there were just check valves in the nozzle that’s in the intake port. The vent on the oil level sensor lets air in to the tank but not out, I think that is working correctly.

Are there check valves at the pump end? I thought there were just check valves in the nozzle that’s in the intake port. The vent on the oil level sensor lets air in to the tank but not out, I think that is working correctly.

either the 717 or the 787 has check valves at the pump end, the other one has them on the fittings going into RV area, can’t remember which one is which

 

[dougamclean]

I pressured tested it today with 5 psi it took about 45 min to loose 1psi. When I built the engine I put 5psi on it for about 5 min and didn’t see any drop so I continued assembling the engine,so it still looks the same as when I built it. The manual doesn’t give a time frame or leak rate so I guess it’s pointing to something else.

That hardly seems enough drop to allow oil to push past a seal into the crankcase...

How long had it been sitting since the motor was last run prior to it's hydro-lock start?

 

[shamrock246]

That hardly seems enough drop to allow oil to push past a seal into the crankcase...

How long had it been sitting since the motor was last run prior to it's hydro-lock start?

I agree that chamber only sees crank pulses from either cavity it was sitting about three weeks in my steel building with all the other toys,I’m thinking something happened with one of the oil pump check valve on that rear cylinder. I’m keeping an eye on it for now it’s going to be a smoke fest when I start it up.

 

[burtshaver2021]

When I first purchased my 95 XP I had the carbs off. One of cylinders just above the rotary valve had filled with oil, the valve was closed on that cylinder. At first I thought it was an inner crank seal that had leaked an enormous amount of oil to fill it that high, but when I rotated the engine the valve opened and the oil dropped into the engine. Now each spring I crank the engine with the spark plugs out just in case buy it hasn’t ever happened again