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F165 crankshaft seal

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Estimable Member
Joined: 5 years ago
Posts: 143
Topic starter  

Some 20 years back I replaced my crankshaft seal with a non-split oil seal using the greased plastic bag method. Recently it started leaking again. My long time A&P let's me perform some maintenance under his supervision. This time I had the split seal type. Connecting the spring went OK after a few tries with the Kelly clamps. But, despite having cleaned and soaped the crankcase, the seal kept opening and ejecting the spring. Sometimes it's better to step back and reassess before getting completely wrapped around the proverbial axle. After another failed attempt I thought I'd try a different route. I tied a thin tie wrap around the seal, and found some 3/4" screws in place of the ones used to install the seal retainers. I then carefully screwed the retainers in which evenly pushed the seal into the crankcase. I then swapped the screws, cut the tie wrap, and finished the install. This is a bit long-winded but I'm hoping it will be of help. 

Happy New Year! 

Prominent Member
Joined: 18 years ago
Posts: 777

Carstsen, of course it makes no difference whether it is a F150 crankcase or a F165 crankcase.

However, I have found that it makes a difference if the crankcase has ever been "overhauled" and line bored by someone like Divco.

It seems that if that is in the history of a crankcase, that it becomes more difficult to replace the crankshaft seal because they usually take  a small cut on the interfacing crankshaft halves but I don't think they rework the seal bore and therefore, the seal bore becomes slightly smaller and it becomes a much tighter fit in seal's  OD and difficult to get started and pushed home in the bore.  In one case, I found it necessary to slightly chamfer the leading edge of the seal to help get it started in the bore.  Also, I always use a thin coat of DC-4 on the OD and the ID of the seal and on the  crankshaft surface and that makes it slip in easier.    I never use any sealant except a very small amount at the split.  With a clean cavity, I have had great success.  The retainers are necessary, some Franklins have them missing. 

Your procedure of using some different length bolts initially to help push the seal is very good and should be helpful to others.

Thanks for the post.


Larry Wheelock

Bret and Bret reacted