Oil in tachometer cable

[jmvolpp]

A slow drip of oil persists from N44305's tachometer cable, despite the attention of 3 mechanics over the last year, starting with the prepurchase inspection. It finds its way to whatever is below it, which is sometimes another gauge or the pilot's leg, but usually the floor. It also gets into the tachometer, which causes it to rebel. After my cleaning the tach out several months ago, and probing the crankcase vent tube for any obstruction, the mechanic's solution at the just completed annual was to apply 2 O-rings at the engine end of the cable - which didn't stop the leak. Engine is A-65 with 160 SMOH and no other major oil leaks. Any suggestions are welcomed.

Mike Volpp

[Guest]

Re: Oil in tachometer cable

Sounds like you need a new oil seal at the tach drive in the rear of the crankcase.

[Wayne]

Re: Oil in tachometer cable

I just replaced mine last weekend. It seems to have worked. No more oily legs.

[Guest]

Re: Oil in tachometer cable

I just replaced mine last weekend. It seems to have worked. No more oily legs.

lol,

Wayne,

If your knees start to squeak you will wish you had left it as is!

Dave

[astjp2]

Re: Oil in tachometer cable

I wound up putting 2 seals in my tach cable housing, one on top of the other...to stop the leak, they only cost about $6.00 each. Tim

[Robert Lees]

Re: Oil in tachometer cable

A small amount of oil in the tacho cable is your friend. It keeps the right-angle tacho drive behind the rpm gauge in the panel lubricated, if you (or your mechanic) forget to remember that it needs lubricating.

Here's a photo of the tacho seal in the crank case threaded thingy, with relevant part numbers. The original brown seal in the photo has the seal lip in the opposite sense of the new blue one...meaning that you have to make sure that the seal lip is facing the crankcase. Where the oil pressure is. If that makes sense.

[Wayne]

Re: Oil in tachometer cable

So are you saying the blue one is installed the other way?

[OldBits2]

Re: Oil in tachometer cable

Oil Seals must be installed with the lip exposed to the INSIDE of the engine in order to trap the oil and crankcase pressures which are used to assist the sealing springs.

I beleive the 'blue' seal above was shown in that position to demonstrate what both sides looked like.

[Robert Lees]

Re: Oil in tachometer cable

Yes, Wayne, for this particular make of seal (the blue one), the lip was on the other side to the bronze-coloured one, so I initially installed it incorrectly (doh!).

Destroyed it getting it out, so put another new one in.

Oldbits is correct.

[jmvolpp]

Re: Oil in tachometer cable

I finally had a chance this morning to check the oil seal and found it to be installed backward. (Picture is what it looked like, with replacement seal alongside) I also learned the housing is left hand threaded which, judging from the channel-lock marks on it, somebody before me didn't know, either! Maybe the same blacksmith that worked over the seal side of it, too? In addition to replacing the seal, I pulled the cable, blew out excess oil and removed the 2 aforementioned O-rings and a flat washer from the engine end of the cable that didn't look to be necessary. I did see there is a groove about 2 cm. from the end of the cable where an O-ring would fit, but that's outside where any oil should be if the seal is good. No chance today to test it after putting it back together - will look forward to that later. Thanks to all for the tips.

Mike V.


Oops! My 163 KB picture is bigger than the forum allows (125 KB) for attachment, but I'd be happy to e-mail it to anyone interested in seeing it.

[Wayne]

Re: Oil in tachometer cable

Hey Mike, I would really like to see that picture,

Thanks
Wayne

[email protected]

[Forrest Barber]

Re: Oil in tachometer cable

still catching up today, yes backward is not good!! I do love this list and the fellows who work out their problems. thanks BOB, RUTHIE & TUCK....DOUG too!