Tach drive oil seal, C145-2

How to keep the Cessna 170 flying and airworthy.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

Post Reply
Hineywheel Bill
Posts: 93
Joined: Fri Feb 17, 2006 8:55 pm

Tach drive oil seal, C145-2

Post by Hineywheel Bill »

I need some advice as the drawing in the IPC isn't very clear:
I need to know which way the seal should be installed in the housing; with the open side toward the engine, or the solid side toward the engine? The one I'm replacing was with the open side toward the engine but that just doesn't look right to me. I just want to get it right so that I don't have to take it off again.
Thanks in advance...
Owner of:
1954 C170B N1921C S/N 26066
Former owner of:
1948 C170 N3815V
1951 C170A N1490D
1946 C140 N76447
User avatar
Bruce Fenstermacher
Posts: 10313
Joined: Tue Apr 23, 2002 11:24 am

Re: Tach drive oil seal, C145-2

Post by Bruce Fenstermacher »

Remember Bill, you sealing oil in the engine.
642714__49989.1457542869.1024.1024.jpg
The side you see in this picture should be towards the inside of the engine.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Hineywheel Bill
Posts: 93
Joined: Fri Feb 17, 2006 8:55 pm

Re: Tach drive oil seal, C145-2

Post by Hineywheel Bill »

Thanks Bruce, that's the way the old one was but it just didn't look right for some reason. A lot of things just don't look right to me any more. :wink:
Owner of:
1954 C170B N1921C S/N 26066
Former owner of:
1948 C170 N3815V
1951 C170A N1490D
1946 C140 N76447
User avatar
GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

Re: Tach drive oil seal, C145-2

Post by GAHorn »

While not applicable particularly to HineywheelBills example... it was pointed out to me in Kelowna by Steve Grimsley that SOME tach drive seals are double-sided/fully-enclosed.... I.E., both sides of the seal are metal. There is one side which has an obvous "seam" where the outside sheet metal overlaps the inside sheet metal cover. That seam should face into the engine if you have such seal.

(I believe that is an older style seal, but may still be encountered if one acquires NOS (New Old Stock). Rubber items such as seals have "shelf lives" that typically are less than 10 years, so hopefully those will not be found in the 22nd century.)

Hope that helps.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
Hineywheel Bill
Posts: 93
Joined: Fri Feb 17, 2006 8:55 pm

Re: Tach drive oil seal, C145-2

Post by Hineywheel Bill »

I have an old spare housing that had a seal in it like the one you described. I have been chasing an oil leak for a while and I think I finally found it, just waiting for another new seal to come in so I can put it all back together. The problem, I think, is that the housing was warped such that the three corners (bolt holes) are drooped down slightly. This can be seen when the housing is sitting on a flat surface. Of course, this allows oil to leak from under the gasket when the oil gets hot. Quite a messy situation after an hour or two of flying.
Owner of:
1954 C170B N1921C S/N 26066
Former owner of:
1948 C170 N3815V
1951 C170A N1490D
1946 C140 N76447
Post Reply