Oil Leak at Tach Cable--Inside cabin

356 Porsche-related discussions and questions.
Post Reply
Message
Author
User avatar
Erik Olsen
356 Fan
Posts: 15
Joined: Mon Aug 13, 2018 8:20 am

Oil Leak at Tach Cable--Inside cabin

#1 Post by Erik Olsen »

New 1963 356-B owner. While trying to put a few miles on the car, I discovered an internal oil drip. Source was the cable to the Tach.Is this typical? Why would oil be getting into the tach cable assembly.Has cable failed? operates fine but need to find a fix here...Advice welcome. Thanks. E. Olsen

User avatar
Doug McDonnell
356 Fan
Posts: 6061
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Oil Leak at Tach Cable--Inside cabin

#2 Post by Doug McDonnell »

Usually due to missing or worn seal where tach cable goes into 3rd Piece or missing shim : https://www.stoddard.com/53907117.html.html See thread here for details: viewtopic.php?f=1&t=45795 And the shim Larry Brooks talks about if you are missing it: https://www.stoddard.com/36905707.html.html Olsen with an E Norwegian from my youth in North Dakota.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

Geoff Fleming
356 Fan
Posts: 1972
Joined: Sun Jan 31, 2010 6:50 pm
Location: Union, New Jersey

Re: Oil Leak at Tach Cable--Inside cabin

#3 Post by Geoff Fleming »

Welcome to the site. This is not an unusual problem with the cable driven tachs, in fact I just replaced my own tach drive seal the other day. I had the same internal drip which you've experienced.
The seal is very inexpensive and a snap to replace.Just unscrew the cap at the engine tach drive..(.opposite end of the cable from the tach), and pry out the old seal then push in the new one. Re-screw the cap and that is it.
I went an extra step and pulled my cable from within the outer sheath, in order to dry it of residual oil. In my case, the oil had penetrated the tach housing and forced me to open it and make the necessary cleaning. Cable is quite easily pulled from the sheath from the tach end.. spread a small tarp or newspapers inside the cabin, in case some oil drips onto the interior.
The good side is that once the seal is replaced, you won't have this problem again for at least 30 years. Porsche later went to the electric tach with the later C series cars. ( Not the early C cars like mine!)

User avatar
Jules Dielen
356 Fan
Posts: 3165
Joined: Fri Mar 28, 2008 3:25 pm
Location: Arizona

Re: Oil Leak at Tach Cable--Inside cabin

#4 Post by Jules Dielen »

seal in the 3rd piece fixed mine :) This site is great :)
Jules

Water pumps are for windshield washers only.

User avatar
Mike Smith
356 Fan
Posts: 1275
Joined: Wed Mar 26, 2008 10:55 am
Tag: Its Only for Fun
Location: Ramsden Heath, Essex, CM11 1HS, UK
Contact:

Re: Oil Leak at Tach Cable--Inside cabin

#5 Post by Mike Smith »

Don`t forget the shim that is also required in this location
Mike Smith (Essex - UK)

User avatar
David Green
356 Fan
Posts: 224
Joined: Thu Dec 06, 2012 3:48 pm
Location: Santa Barbara

Re: Oil Leak at Tach Cable--Inside cabin

#6 Post by David Green »

To avoid the problem in the future drill a small (1/16") hole in the cable ferrule at the engine end. If the seal leaks the oil will drip out there before being screw-pumped up to the tach and an occasional inspection of the engine underside will show the leak.
David

Brad Ripley
356 Fan
Posts: 4205
Joined: Tue Mar 25, 2008 9:28 pm

Re: Oil Leak at Tach Cable--Inside cabin

#7 Post by Brad Ripley »

To detail the oil pump seals, etc , below is an illustration with important part numbers.

Brad Ripley
356 Fan
Posts: 4205
Joined: Tue Mar 25, 2008 9:28 pm

Re: Oil Leak at Tach Cable--Inside cabin

#8 Post by Brad Ripley »

illus below
Attachments
Oil pump illus .jpg

User avatar
Doug McDonnell
356 Fan
Posts: 6061
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Oil Leak at Tach Cable--Inside cabin

#9 Post by Doug McDonnell »

Kind of you to label them all Brad. Takes all the guess work out of it.
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

Eric Benner
356 Fan
Posts: 5
Joined: Thu Jan 12, 2017 9:39 pm

Re: Oil Leak at Tach Cable--Inside cabin

#10 Post by Eric Benner »

I have found that a speedometer cable seal from a Volvo 240/260 is a better alternative and seals every time. Can be sourced from IPD Volvo located in Oregon. Part#61153003548. Just a tip from 35 years experience. Hope this helps

Jan Kolm
356 Fan
Posts: 600
Joined: Wed Mar 26, 2008 1:35 am
Location: Colorado

Re: Oil Leak at Tach Cable--Inside cabin

#11 Post by Jan Kolm »

I recall a post years ago in the old 356 Talk about a batch of replacement tach cables, where the strands were twisted in the wrong direction, and the cable acted like an Archimedes Screw, drawing oil up into the passenger compartment. The only fix was to replace the cable with one wound to keep the oil in the crankcase.
Jan Kolm
356 Registry #1066
1960 1600N Coupe

User avatar
Simon Bennett
356 Fan
Posts: 11
Joined: Tue Jun 16, 2020 12:53 pm

Re: Oil Leak at Tach Cable--Inside cabin

#12 Post by Simon Bennett »

Thanks for the excellent information above. I'm quite a noob on 356's but have experience with beetles.

In the great diagram above, what number parts are the seal and the shim? There seem to be external (that I am hoping are the ones) and internal that imply removing the oil pump. Should part number 54 solve it? Great info on Volvo part too, as I'm not in the USA and the original will take months to arrive.

Note my car (356B T5 S90) started doing this after an engine rebuild.

Thanks!

User avatar
Doug McDonnell
356 Fan
Posts: 6061
Joined: Sat Apr 05, 2008 8:21 am
Location: Augusta,Michigan

Re: Oil Leak at Tach Cable--Inside cabin

#13 Post by Doug McDonnell »

Brad labeled the parts numbers of seal and washer #54 and #55 above in post #8
1965 356C 2000 BMW 740i Sport 1967 Honda CL77 There is never enough time to do it right, but always enough time to do it over.

User avatar
Don Gale
356 Fan
Posts: 1170
Joined: Wed Jul 26, 2017 6:27 pm
Tag: Black A's Matter
Location: Albuquerque
Contact:

Re: Oil Leak at Tach Cable--Inside cabin

#14 Post by Don Gale »

As fate would have it, the correct lay of the inner cable is such that it will behave as an Archimedes screw, drawing oil up the cable from the pump cover to the tach, hence the need for the seal at the oil pump. It has to do with whether the spiral wound inner cable constricts on its core or wants to expand, which would cause premature failure of the outer sheath if the inner were to unravel. If yours is leaking at the tach, then you have the correct cable.

https://www.aircraftspruce.com/catalog/ ... cables.php

"Available in left and right lay rotation. Add -R to the part number for Right Lay.
1. To determine cable rotation, note the rotation direction of the tach drive socket on the engine while looking directly at the tach drive on the engine.
2. If the drive socket rotates clockwise, a right lay inner cable is required.
3. If the drive socket rotates counter-clockwise, a left lay inner cable is required.
4. The rotation direction of the tach needle does not affect which lay should be used."
1958 356A 1600 Super Sunroof Coupe
former 1966 Euro 912 Sunroof
former 1978 Intermeccanica Speedster w/'68 912
Member Since 1983, #4039

"Nostalgia isn't what it used to be"

Post Reply