717 crank seal leak

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i have some 717 motors and one has two issues first issue is the coupler crank seal leaks. i figure spin motor remove bottom crank case change seals on each end and put back together . is there anything to mess up my plan that makes it necessary to remove cylinders ?? and before i take it apart is there a way for me to find out if the center crank seals are bad ??
 
You need to pressure test the engine.
okay . how much psi do i apply into that small cavity. i can see to much pressure will blow out a good seal. lol . and how long will the pressure need to hold for.
when i do a search i dont get what im looking for most of the time . ill look up pressure test and see what i get thanks again
 
You need to block off the carb and exhaust outlets then put 8 psi on the pulse line fitting. It should hold 8 psi for at least 10 minutes.
 
you can test the center crank seals by themselves by just pressure testing the RV cavity. Personally, I put 8 lbs of pressure in my engines
 
Dan is correct.
On an old engine it is good to pressure test the entire thing too so that you can make sure you don't have any intake leaks eiter. I have had a few that ran fine but had the rotary cover o-ring leaking.

As far as only pulling the bottom crankcase to do the crank seals I think it is theoretically possible but I can't think of ever hearing anyone doing it that way so I can't say 100% sure you can.
 
Dan is correct.
On an old engine it is good to pressure test the entire thing too so that you can make sure you don't have any intake leaks eiter. I have had a few that ran fine but had the rotary cover o-ring leaking.

As far as only pulling the bottom crankcase to do the crank seals I think it is theoretically possible but I can't think of ever hearing anyone doing it that way so I can't say 100% sure you can.
yes it is possible . im basically done . but i have a bad bearing that i have to address . i didnt want to remove cylinders because their salt water motors and ill certainly wind up with at least one broken bolt and hours with a propane torch.
 
So how to you plan to address the bad bearing? You can't press an old one off and a new one on with the crank in an engine and it's not typical for just one crank bearing to be bad, the others are typically on the way out especially if any water got into the engine.
 
So how to you plan to address the bad bearing? You can't press an old one off and a new one on with the crank in an engine and it's not typical for just one crank bearing to be bad, the others are typically on the way out especially if any water got into the engine.
i was kind of updating my original question about if the seal only could be changed with out taking the cylinders off. and i found yes i can do it ,easy .
but the two bad bearings on the coupler side certainly changed things and i did get the first bearing off with the crank installed with the rods and pistons and cylinders( the piston in one cylinder is at TDC and the other total opposite) the bearing fall apart i took the 9 balls out and outer race easy by hand and the crank assembly lift up high enough to removed the inner race piece with a three arm puller. and im afraid that at this point where i left off is were like you are saying the party is over. lol unless i find a way to remove the inner bearing and then install two new bearings not very likely . but with my collection of pullers etc etc i will at least entertain the thought for a little bit of time. no water got into engine . i commented on another post you had with my findings my engine isnt a good candidate any longer but before i opened it up and only knowing the one seal was leaking , it would have been a walk in the park. but to try to keep this story half the size im leaving this engine as needs work.
 
At least we know you could do seals without a complete tear down so not for nothing.

For the crank you can’t get to the inner bearings. And you wouldn’t be able to press on new outer bearings.

Your best bet might be a full reman engine from SBT with a warranty.
 
At least we know you could do seals without a complete tear down so not for nothing.

For the crank you can’t get to the inner bearings. And you wouldn’t be able to press on new outer bearings.

Your best bet might be a full reman engine from SBT with a warranty.
i ment the inner of the two outer bearings . i know about the two bearings and two seals in the center . i try to make story as short as possible and i always make a mistake wording things this is why im a mechanic at least i think i am thanks much
 
i found on my first two motors i took apart that when one of these motors breaks , seizes or low compression etc etc .. what ever the issue i ended up with less then half of the engine parts as being good to use over. from just a bad coupler seal(i thought at first sight ) to havin almost nothing left after dissambly ,but each engine came with a ski and trailer for $300. i took apart a third engine that was running . i took it apart because the cylinders are rotted at top where meets the head . so i have a third motor minus cylinders ......................... can the sleeves be pressed out and into a different cylinders water jacket ????????????????????????. its a 717 motor
 
Yes cylinder sleeves can be swapped but they have to bored to size afterwards since they have to be heated and can deform. They won’t be the same after going into new cylinders.

You might want to look at the top end exchanges from SBT.
 
yes im weighing out my options . after three motors . i have one good block (rotary surface). and two cranks . a two carb set up, a single carb set up, ,good heads . 2 cylinders and pistons now are the issue which to use . i have to complete my disassembly of the sbt motor to see condion of the good sleeve one has low compression , .. being its from sbt i bet its over size ? . i like the original brp pistons they look as there quality is a little better the the oversize set. i trying to do this build without buying anything more. i have the money, but this is just my thing . tinker and use what i have . i prefer to cut out any dealership and or machine shop i dont want to even buy a new top end i should have two good out of 6 lol ., should.... piston rings i will buy ! how much is a set for both pistons would you think roughly. ? if i use the original brp pistons. vs oversize is there a price difference between these type piston rings and quality . i may have no choice but it may alter my decision . if the overbore is the next size what would the cc's be ? any hp gain from larger bore i would think a little. should the jets have been changed for more fuel. the oversize has 175 main jet single carb ,i guess after running motor and reading the piston for the sure answer but usually there a recommendation to start with . a lot of questions i know .... you know a lot more then i do , i do know do it right the first time .. im being cheap but as long as i build smart it will be good !!! has anyone ever run a different size bore in each cylinder and have a good running motor ??? thanks for suggestions , i figure id throw this stuff out there in my post i dont want to bother anyone to answer all this i can figure it out but it will take a lot of time reading the posts , ill get around to it but i figure this may help others also whom like to build on a budget . thanks again
 
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