787 crank seal leak

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DanSquires

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I had a ski come in for repairs this week, I thought I would share a quick video I took.


This is an 05 GTI LE RFI, customer issue is that it would hydrolock. Pull the plugs and oil would shoot out of the front cylinder. I knew this would be the issue, so I removed the engine and split the case.. making sure to not disturb the crank in the upper case so I could verify the issue, and shoot the video.
In this case, the front cylinder was the one that was hydrolocking, which is the seal that turned super easy in the video.

The fix is to clean it up, add 518 to the seal grooves, bolt it back together.

I don't think this is a well known issue, as I often see the comment "needs a new crank" when someone complains about leaking seals.. It's often not the case.

Sorry about the background noise, compressor kicked on just as I hit the record button
 
When you say add 518 to the seal grooves, do you mean the grooves in the case (both sides?) or directly to the seal?
 
In the case. Pretty much standard operating procedure when rebuilding an engine with center seals anyways
 
Might have to do this... good to know a crank isnt the only solution.

engine started hydro locking after long storage last season. But I also replaced the RV cover just before with a salvaged one. Hoping the injectors on it are leaking.

Going to tear into it next week to see.
 
Interesting. I tried a different approach on my 787 with oil in the mag cylinder and am having good luck so far. I'm more familiar with the 580 and 657s, it seems like most of the bad seal posts are related to the 787.
 
Interesting. I tried a different approach on my 787 with oil in the mag cylinder and am having good luck so far. I'm more familiar with the 580 and 657s, it seems like most of the bad seal posts are related to the 787.
What was the approach you tried?
 
I disconnected my RV oil lines at the tank, drained the RV chamber, pulled a light vac on the lower line and poured in a very thick oil/very light weight grease until the chamber was full then sealed the lines. I did leave a vent hole in the end of the upper line.

I had a 97 GTX given to me by the original owners. It was having the typical oil buildup in the mag cylinder that required pulling the plug and cranking the oil out if it sat for longer than a week. The machine had been babied it's whole life and only had 97 hours on the original motor.

I had been on the forum for a while for my XP and had already read many posts about the 787 inner seals giving out. I figured I would try an experiment and use something other than the synthetic oil in the RV chamber. I looked around for a while and found what I thought would work and did the swap. I have around 120 hours on it now, most of it wide open running, and have not had any troubles so far. It starts right up without any need to pull the plug or producing the smoke cloud it used to. I do check for oil buildup by pulling the plug and cranking a cold motor every month to see if there is a change, so far so good.

My thinking was if I have to replace the crank anyhow I'm going to try and see if I can get more life out of it. I'm gambling that if the idea fails I'll just have to do a crank and RV shaft rebuild.

The big word here is EXPERIMENT, it's not a solution. Try it at your own risk since I'm still not convinced after 20 hrs. For me it needs to go hundreds before I'll suggest it to anyone else.
 
I disconnected my RV oil lines at the tank, drained the RV chamber, pulled a light vac on the lower line and poured in a very thick oil/very light weight grease until the chamber was full then sealed the lines. I did leave a vent hole in the end of the upper line.

I had a 97 GTX given to me by the original owners. It was having the typical oil buildup in the mag cylinder that required pulling the plug and cranking the oil out if it sat for longer than a week. The machine had been babied it's whole life and only had 97 hours on the original motor.

I had been on the forum for a while for my XP and had already read many posts about the 787 inner seals giving out. I figured I would try an experiment and use something other than the synthetic oil in the RV chamber. I looked around for a while and found what I thought would work and did the swap. I have around 120 hours on it now, most of it wide open running, and have not had any troubles so far. It starts right up without any need to pull the plug or producing the smoke cloud it used to. I do check for oil buildup by pulling the plug and cranking a cold motor every month to see if there is a change, so far so good.

My thinking was if I have to replace the crank anyhow I'm going to try and see if I can get more life out of it. I'm gambling that if the idea fails I'll just have to do a crank and RV shaft rebuild.

The big word here is EXPERIMENT, it's not a solution. Try it at your own risk since I'm still not convinced after 20 hrs. For me it needs to go hundreds before I'll suggest it to anyone else.

I've got a buddy that did the same thing, except he added a grease zerk.. pumped it full of axle grease like 5 years ago and it still goes like all is good in the world.
 
I would think using boat outdrive grease/oil or that thick stuff they use would be a good option. It is thick so would not leak easy and is specifically made for 90 degree gear drives like in the rotary chamber. I would think it would be safe on brass also.
 
I would think using boat outdrive grease/oil or that thick stuff they use would be a good option. It is thick so would not leak easy and is specifically made for 90 degree gear drives like in the rotary chamber. I would think it would be safe on brass also.

All good and dandy for people "in the know"
but 99% of customers (like this) don't want a shortcut fix, they want a proper repair..

I dont know why SeaDoo dorked the dog on these center seals for the last few years of the 787 production, I've only seen this on the black RFI engines. Same timeframe as they changed from 518
 
A proper repair would be new inner crank seals as the seal lip is eventually going to fail from wear as all seals do. I find it hard to believe all of these are leaking from around the OD of the seal and it's not just the 787's that have leaking inner crank seals, it's all the rotary valve models the suffer from it at some point. Also new inner seals fit tight in the cases so something is happening to the seals over time if they are getting loose in the groove. But then again what do i know, I have been wrong before. I also don't think you can blame Seadoo for 20+ year old seals starting to leak at some point.
 
A proper repair would be new inner crank seals as the seal lip is eventually going to fail from wear as all seals do. I find it hard to believe all of these are leaking from around the OD of the seal and it's not just the 787's that have leaking inner crank seals, it's all the rotary valve models the suffer from it at some point. Also new inner seals fit tight in the cases so something is happening to the seals over time if they are getting loose in the groove. But then again what do i know, I have been wrong before. I also don't think you can blame Seadoo for 20+ year old seals starting to leak at some point.

Don't know about all, but the late 787's it's extremely common, and a discussion I'd had with fullbore several times over. Late model RFI seals spin in their cases, the fix is to split them, clean them, seal them. Never another issue.

20+ year old, no, 63 hours, yes (the lowest hours I've had to do this repair) They changed the material, then slippage started. All at the same time they steered away from the 518 on everything and bought out Evinrude
 
And here we all assumed the red crank seals were better, the one thing for sure about Seadoo's is you are always learning something new.
 
I've got a buddy that did the same thing, except he added a grease zerk.. pumped it full of axle grease like 5 years ago and it still goes like all is good in the world.

I wanted to stay away from a heavier grease and go with something that, hopefully, turned more liquid in a warm motor. I was also looking for something I could flush out without splitting the cases.

Hey, if we had it all figured out then part of the fun would be lost.
 
In the case. Pretty much standard operating procedure when rebuilding an engine with center seals anyways

You're saying it's standard procedure with center crank seals to fill both sides of the groove in the case with 518 gasket maker to lock the seals in place and close up potential leak points? In your opinion should this be done on a fresh rebuild as well? We're also assuming that the leak is at the case interface as opposed to the crankshaft interface in which case the seal wouldn't spin like that.

Only reason I replied to this thread is that I strongly believe I have a leaking crank seal as well with the 787 (98 GTX RFI). Hydrolocked today after trying to start with a new regulator/rectifier and then got a bunch of oil out of the plug hole on the mag cylinder. It ran well for the most part 2.5 weeks ago, had a rough idle which may be related but ran great at speed. Today I tried to startup after clearing the cylinder but it would only sputter for a second or two and die again, sure I could get it to run with a bit more effort but ran out of time. These seem like good solutions opposed to a new or rebuilt crankshaft though.

Appreciate the thread, always good to see some hard evidence of a problem especially with all the threads about the same topic.
 
Dan-if you were to choose in a descending order of repair options, how would you rank your repair options, ie, this might be kind of obvious but I like your thinking in this post and would be curious to hear your thoughts.

1 Outright crank replacement and 518 sealing the new seals in place (obvious expense answer)
2 Split case and seal existing seals with 518
3 remove or cut supply RV oil supply line and install grease zirk in hose end and pump the RV cavity full until it presents in the vent tub several inches above the entry fitting (would be curious to know your choice on grease, I'm leaning toward the XPS 293550010 for the driveshaft couplings)
4 ball valve in the supply line (done this already need to see how it performs, used a 1/2 barbed SharkBite, fit perfectly)

Thanks in advance--Mark

64713996352__CE101B34-F488-437A-910A-2F9D30C08116.jpg
 
This may be a dumb question.....does the oil in the rotary chamber flow? Or does it just fill up from the oil tank and just sit? Is the 717 similar? I have a 717 with leaky crank seals but has good compression and ran great.
 
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This may be a dumb question.....does the oil in the rotary chamber flow? Or does it just fill up from the oil tank and just sit? Is the 717 similar? I have a 717 with leaky crank seals but has good compression and ran great.
I had/have the same question, the lines are gravity feed to the top RV oil port, and the bottom line runs back to the vent connection on top of the tank, and based on the images here, there sure doesn't seem to be any motive flow of any kind in the RV cavity itself in the form of an impeller or other means driven by the RV shaft or crank shaft?
 
I just started a new topic on this very issue in a '97 GSI with a 717. I will keep an eye on this thread.
 
If
I had/have the same question, the lines are gravity feed to the top RV oil port, and the bottom line runs back to the vent connection on top of the tank, and based on the images here, there sure doesn't seem to be any motive flow of any kind in the RV cavity itself in the form of an impeller or other means driven by the RV shaft or crank shaft?
there is no “flow” could you not fill the rootary valve chamber up with 00 cap the lines and still use your oil injection
 
Correct, there is no flow of the oil. It is filled from the intake side and air is purged from the exhaust side. It is just a vented chamber full of oil.
The only thing in there is two inner crank seals, two bearings for the rotary shaft, the rotary shaft and gear and a rotary shaft oil seal.
You could try running some 90/140 gear oil and see if that slows down the leak but you would have to disconnect if from the oil tank and would be a mess trying to burn that out of the crankcase if the leak continues.
 
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