tonybcrazy
New Member
I'm looking for some input from Seadoo engine gurus to shed light on a failed engine. I recently purchased a 99 GSX RFI fixer upper pwc. I am not knew to PWCs but this is my first Sea-doo. I didn't water test prior to purchase due to a damaged impeller but engine started easily on the trailer and a compression test showed 150 PSI in both cylinders. I do not currently know many hours are on the ski. After fixing most of what was wrong (new to me oil tank, impeller, trim unit) I water tested the unit and was severely disappointed. The craft would not rev out and had a noticeable knock to the engine. I haven't fully figured out why it wouldn't rev out yet but decided the engine knock was more important to fix first. I moved the engine over by hand and rocking it back and forth with the mag piston near tdc made a loud clanking noise. I pulled the engine and removed the cylinder and found a mag side piston that was heavily scored mostly on the exhaust side. Compared to the PTO side the mag side seems less oily so I am wondering if it was an oiling problem.
Here was I know about the oiling system:
The tank was split at the seam and leaked.
The oil pump appeared to be timed correctly.
I don't think the previous owner was using seadoo xps synthetic since the oil in the tank was blue not purple.
It doesn't look like the injection lines leaked though there was so much oil everywhere from the leaking tank it could be hard to tell.
Does anyone know how the crankcase oiling system works? I didn't find much on it in the service manual but I should probably re-read that section. I would like to get this figured out so I can make a decision on how I am going to rebuild. I haven't settled on SBT or WSM piston kits and having my cylinders locally machined or just springing for the SBT top end kit. This is purely a budget rec boat so reliability and cost are both important.
I also have a question about reusing the crank. I checked the rod big end axial clearance and that is fine though the mag side is more worn than the pto. I haven't measured rod big end radial clearance but it feels pretty tight still. The small end has me wondering though. When the pistons were still on the mag piston had a bit more wiggle to it than the pto side. I removed the pistons and measured the rod small end inside diameters. I need to bring home a better set of mic's from work but on initial measurements the pto side measures 24.00 MM. The mag side appears to be a little out of round and measures 24.00 to 24.02 depending on where the measurement is taken. The small end bore on the mag side has some blueing which I believe showed it was getting a bit too hot probably from lack of oil. The manual only specifies small end clearance to the wrist pin and bearings and without knowing what those diameters are new I have no idea if the crank would be usable still. I would prefer to reuse it if everything else checks out but I need to know what the small end ID is.
Any help offered will be appreciated.
Here was I know about the oiling system:
The tank was split at the seam and leaked.
The oil pump appeared to be timed correctly.
I don't think the previous owner was using seadoo xps synthetic since the oil in the tank was blue not purple.
It doesn't look like the injection lines leaked though there was so much oil everywhere from the leaking tank it could be hard to tell.
Does anyone know how the crankcase oiling system works? I didn't find much on it in the service manual but I should probably re-read that section. I would like to get this figured out so I can make a decision on how I am going to rebuild. I haven't settled on SBT or WSM piston kits and having my cylinders locally machined or just springing for the SBT top end kit. This is purely a budget rec boat so reliability and cost are both important.
I also have a question about reusing the crank. I checked the rod big end axial clearance and that is fine though the mag side is more worn than the pto. I haven't measured rod big end radial clearance but it feels pretty tight still. The small end has me wondering though. When the pistons were still on the mag piston had a bit more wiggle to it than the pto side. I removed the pistons and measured the rod small end inside diameters. I need to bring home a better set of mic's from work but on initial measurements the pto side measures 24.00 MM. The mag side appears to be a little out of round and measures 24.00 to 24.02 depending on where the measurement is taken. The small end bore on the mag side has some blueing which I believe showed it was getting a bit too hot probably from lack of oil. The manual only specifies small end clearance to the wrist pin and bearings and without knowing what those diameters are new I have no idea if the crank would be usable still. I would prefer to reuse it if everything else checks out but I need to know what the small end ID is.
Any help offered will be appreciated.
