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FF seal leak

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Crossley Stephenson
Posts: 231
Joined: Wed Feb 10, 2016 9:15 pm
Location: Victoria, Australia

FF seal leak

Post by Crossley Stephenson » Sat Dec 01, 2018 7:04 am

Tell me it isn't so....

Rebuilt engine, rebuilt gearbox, new seal in FF...reassemble and install in NDHC and a couple of days later a small puddle of very clean oil. Investigation reveals probably from FF seal. I have done a couple and believe installation is correct.

Some internet searching found "To be effective, a lip seal must maintain proper contact with its rotating counterpart. This will be influenced by proper selection, installation and care of the seal once it is installed. I’ve often seen a new lip seal start to leak as soon as it was put into service. This typically is due to improper installation. Other seals will leak initially but then stop leaking once the seal material has seated to the shaft."

Hopefully this is true. A local mechanic said sometimes lips seals need to form to the shaft - a sort of running in period.

Any comments, advice?


Rolf B.
Posts: 78
Joined: Wed Apr 05, 2017 7:07 pm
Location: 68309 Mannheim, Germany

Re: FF seal leak

Post by Rolf B. » Sat Dec 01, 2018 8:34 am

Hello Michael,

some months ago my son and I had overhauled and reassembled the fluid flywheel of our Daimler 15. Then it was attached to the engine and filled with oil. The complete unit sat beside our car for a while because we hadn't found time to install the unit into the engine bay. After some three weeks we saw oil flowing out of the center of the fluid flywheel. First we thought the leaking reason is the rotary shaft seal.

To cut a long story short, the fuid flywheel was again completely dismanteled and then after a lot of investigations we found the reason for the leakage. At the end of the inner driving splines is a pressed-in cover plate. And there has been a micro gap which allowed by hydrostatic pressure leaking the oil. After popping out the cover plate we cleaned everything thoroughly and the glued in the cover plate with Loctite 290.

Many weeks after assembling the fluid flywheel, attaching it to the engine and refilling it with oil, there's no more leaking. It's just been this little micro gap in the cover plate at the end of the the spline.

Rolf B.

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