The International Cessna^® 170 Association

Has anyone experianced this problem? I have a 49 c170a with a recently oh'd c145 (0-300) which runs great and would be 'leak free' except for the generator seal. I've checked the generator run-out and polished the seal race. It even leaks when just sitting. Would the alternater conversion cure this problem? Any suggestions would be greatly appriciated......Thanks in advance.
Jim
caddraw@uslink.net

I currently have this problem in my '54 170B. I'm living with it until next oil change. George put me onto the correct seal numbers and the total cost of parts should not be over $15 or so. There are also a couple of good articles in the Association SRAM that give some good advise concerning the generator shaft seal. I wouldn't convert to an alternator just to lick a gen shaft seal. The alternator shaft could leak just as well, and those prices....in my humble opion...for the alternator kits just are not low enough to warrant the conversion. I think a good 35 amp generator is all anyone needs...unless you have one of those Cessna flasher beacons that hog 10 amps and then throw in a pitot tube heater and couple of landing lights on for extended periods.

wa4jr wrote:I currently have this problem in my '54 170B. I'm living with it until next oil change. George put me onto the correct seal numbers and the total cost of parts should not be over $15 or so. There are also a couple of good articles in the Association SRAM that give some good advise concerning the generator shaft seal. I wouldn't convert to an alternator just to lick a gen shaft seal. The alternator shaft could leak just as well, and those prices....in my humble opion...for the alternator kits just are not low enough to warrant the conversion. I think a good 35 amp generator is all anyone needs...unless you have one of those Cessna flasher beacons that hog 10 amps and then throw in a pitot tube heater and couple of landing lights on for extended periods.

Thanks for your reply. Would you happen to know what those part #'s are? If not how can I contact George? Also, how can I view the 'SRAM' concerning this seal? Thanks again.

The part numbers as I got them from George are: Tach oil seal Cont. PN 642714 going for $4.70, the tach/gen gasket PN 35019 for $3.80 and the gen oil seal PN 352068 for $4.20. All these are available from Aircraft Spruce 877-477-7823. I have not ordered yet, but will be doing so very soon. Had to get the hangar secured first!

SRAM is the Service Related Articles Manual published by the Association. It contains every service and maintenance related article ever published by the TIC170A. See the "Store" link on the TIC170A home page and you'll find it there - $48.00 plus shipping.

I bought a SRAM book when they first came out,& I think that it's overpriced. It's just a collection of short "how-I-done-it" type articles culled from the 170 News back issues. No dates on anything,sorta like The 170 Book,a lot of information is maybe a bit out of date (like prices!). I would recommend buying it if it were cheaper. The 170 Book is $20,seems like the SRAM book should be maybe 30-ish?
I'm waiting to see what's up with the 170 maintenance manual the Association has been talking about producing. Does anyone know what kind of time frame before they're available? Hope the pricing will be reasonable.

Eric

There is an internal seal that I had to change out to fix my leak. It was a quick fix with the help of my A&P and once changed I have had a dry generator for the last couple years. I have done the same thing... expecting it to be worse than it really is only to have my mechanic fix it in short order!

I just put my new (rebuilt) generator on this morning. I can verify the Tach seal is PN642714. My generator / tach gasket, single piece unit, was PN652072, which of course, George had given me. I put a light film of Permatex Aviation Form-a-Gasket Sealant Liquid (from NAPA), on both sides of the gasket. It's supposed to stay plyable for all time.
After some local flying, I discovered oil dripping on the passenger foot pedals, OK I must have got the tach seal in bad. Nope, it appears to be the pressure guage line. How'd that happen? Pulled the line (which changes to copper tubing inside the firewall) pressure tested it and could find nothing. Reinstalled it and the glove box and etc.. Started engine, leaked again, right in the fitting just inside the fire wall. Cranked down on the fitting, it's seems to be holding however I'm going to wonder from now on if it's fixed or not. The connection is a barrel type swedge that connects the 2 pieces of tubing together.