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

 

[shamrock246]

I left it pressurized over night and checked it after lunch and it still had 3psi. I think it’s safe to say it’s not the crank seals.

 

[dougamclean]

I left it pressurized over night and checked it after lunch and it still had 3psi. I think it’s safe to say it’s not the crank seals.

I'd agree with that..

 

[burtshaver2021]

I left it pressurized over night and checked it after lunch and it still had 3psi. I think it’s safe to say it’s not the crank seals.

Agree,

 

[shamrock246]

Well it looks like the engine is coming out. The rear crankcase keeps filling with oil even with the valve on the oil supply closed it just comes in from the return line. Maybe it’s just crankcase sealant that failed.

 

[mikidymac]

I haven’t seen the sealant fail. It’s typically the seals.

 

[shamrock246]

Could they have spun in the case? I find in kinda weird that they failed after 12 hours but this is my first 787 rebuild maybe I did something wrong.

 

[shamrock246]

I took the engine apart today and I found the seal for the rear cylinder will rotate ( with some resistance) with the crank while the front stays stationary with the case half’s split. I don’t see any damage to the seal or to the case’s. The seal tension on the crank feels the same between both seals so I think the leak was between the seal and case. The assembly video on the Today we wrench video he puts 518 in the seal grooves and mentions that a lot of these inner crank leaks are because this isn’t done I did not do this. I used 1211 to seal case half’s but did not put anything in the grooves should I clean every up and put 1211,518 or something else in the grooves and reassemble it since I don’t see any visible damage to anything?

 

[Seadoo Tuner]

Was into my local 2 stroke Seadoo guru's shop this week and he showed me an example of bad crank bearings on one of the cranks he had out. He also mentioned to put sealant on the edges of the crank seals to prevent future spinning. Saw the same thing on the youtube channel "Seadoo Refurb" who was re-building a 720 engine - he also said put sealant on the crank seals edge.

 

[shamrock246]

Yeah, I was just doing some research on it and found a few threads of people doing this to prevent them from spinning/ leaking. I’m going to use Honda bond 4 on everything this time.

 

[burtshaver2021]

I m pretty sure they use 518 on the today we wrench videos

 

[shamrock246]

Yeah they use it on everything but it looks there are better sealants than 518 for the cases. Maybe I could use Honda bond on everything else and 518 on the crank seals.

 

[burtshaver2021]

Yeah they use it on everything but it looks there are better sealants than 518 for the cases. Maybe I could use Honda bond on everything else and 518 on the crank seals.

Agree, they used 518 on the seals and Honda bond or equivalent on the cases

 

[shamrock246]

I think I’ll try that.

 

[mikidymac]

I have never used sealant on the seals, they are rubber and should seal dry
But I only ever use OEM seals. The tolerances on today’s aftermarket seals a definitely questionable.
518 is not fuel resistant so I wouldn’t use it on cases or seals personally. Love 1184, motoseal, hondabond, Yamato’s, all the same stuff. I would use that on problem seals before 518.

And all seadoo engines need to be pressure tested after taking apart.