1999 GTX RFI 787 crankcase oil line tap fitted

[rodoz]

Engine now has 264 hrs, the cylinder heads have never been off.
I fitted a ball valve/tap to the crankcase oil supply line at 248 hrs, to stop crankcase filling with oil during winter layup.
Engine runs great, max engine speed 6970 rpm at 52 mph.
I presume that the innermost crankcase seals are slowly rotating.
Otherwise, top end and bottom end seem fine.
My questions is, do the rotating seals damage the crankcase ?
Unless advised otherwise, my intention is to not touch the crankshaft.
I am considering doing a top end overhaul and new injectors.
I have recently renewed jet pump, fuel system and oil system.
.

 

[etemplet]

I don't see how the inner lip seals can easily rotate. There isn't enough drag to make them move. I think the seals get worn. You don't need new injectors but you can send them out for cleaning. I'd replace the filters in the fuel canister for sure.

I wouldn't worry about the inner lip seal leak at all. You have it addressed. I have a lot of experience with those. If I don't close the valve my wife's GTX will hydrolock after 10 days. I've let this ski sit for 9 months with the valve closed and it starts right up and runs great. I won't touch this engine.

From your numbers sounds like it is doing great. I'd be tempted to do nothing if the compression readings are good. Keep riding it !!

 

[rodoz]

Thanks for your reply and good information. I saw a Utube video from ”Today We Wrench’ and in the article titled ’Seadoo DIY series Ep 2 Engine Assembly’, at 2 minute 56 second mark the presenter advises to add loctite 518 to the inner seals to stop them rotating. This seemed feasible to me and that's what gave me the idea about rotating sealsl. I have never split the crankcase on any watercraft.

As it is winter in Australia, I have been doing some Seadoo maintenance. I have cleaned the mud from the bottom of the fuel tank and have just received new filter screens for the pump pick up in the tank. I am also fitting bearings and wear ring to the jet pump. The originally fitted wear ring had acceptable clearance, less than 8/10 ths of a mm however great big chunks of the wear ring was missing.

I did a compression test this morning. As the fuel tank is out, l did this test on a cold engine which is not ideal and the result was 136 psi on the mag cylinder and 135 on the PTO cylinder. I took the Rave valves out and saw a slight scouring on the top ring of the PTO cylinder.

I sat and thought about it for a long time......... yes, no, yes, then finally decided to take the head off to check the condition of the cylinder walls.
So now I have the top cover off. Qty 3 of the 12 cover bolts broke or sheared off at the start of the threaded section and one side of the head is stuck to the cylinder.

I have used my oxygen and acetylene kit to heat up the head to try and free the threads but so far no luck. I have sprayed it with WD 40 to soak overnight.

So, I wish that I had taken your advice and left it alone. I was never worried about it being a bit down on power, I just wanted to make sure it didn't seize in the bore or break a ring.

I will try to get the head off again tomorrow. The engine is still installed. Before I used the oxygen/acetylene kit I removed the fuel rail, the injectors were very rusty and the clips holding the injectors to the rail were so rusty they fell apart when I tried to remove them. So I am glad that I found this problem before a leak occurred.

Any advice you can offer regarding my head that is stuck on the MAG side cylinder would be appreciated. Regards.