Bad Crank Seal?
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Bad Crank Seal?

This is a discussion on Bad Crank Seal? within the Vintage forums, part of the Snowmobiles category; I'm selling a 1974 Cheetah 440. One guy called and asked if I was sure the crank seal was good. How the heck do I ...

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Thread: Bad Crank Seal?

  1. #1
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    I'm selling a 1974 Cheetah 440. One guy called and asked if I was sure the crank seal was good. How the heck do I tell??
    Thanks Guys!
    Scooter

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    Start the motor, take a propane tourch(hand held one), don't light it and spray the gas near the pto side behind the clutch.
    If it speeds up that seal is bad. Its harder to do to the recoil side but try the same thing there. Good luck!

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    most people that I know of use Carb spray instead of the torch. I have no idea how you would be able to check the PTO side as the recoil and flywheel are in the way.
    He may be asking about the center seal, those are notorious on these engines and probably has been replaced with the aluminum one. But if you havent had it apart, you wont know for sure.

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    The best way to check the seals would be to perform a leak down test, but most people do not have the tools to do this at home. Basically you remove the exhaust and carbs, plug the intake and exhaust ports, then the motor must be preasurized for 6 mins at 6Psi. If it loses more then 1 psi in 6 minutes, then there is a bad seal somewhere that needs to be found. Brake cleaner works very well for finding air leaks as well, as previously noted, PTO seal is easy to check, Mag side is much harder.

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    Quote Originally Posted by Scootertrash
    I'm selling a 1974 Cheetah 440. One guy called and asked if I was sure the crank seal was good. How the heck do I tell??
    Thanks Guys! a leak down test...don't have the stuff for that...look at the pto side..is it torn...My oppinion if it starts well and runs good, the seals are alright..if you have to prime it and You cnam't dial the carbs in....You may have bad seals....So what put some in it......I love My 74 340..i put an electronic ignition and a Mikuni carb on it.....
    Scooter

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