The International Cessna 170 Association

I've searched the forum quite a while for a direct answer to this question. I'm pretty sure I know the answer using common sense, but I'll ask it anyway given I haven't seen a direct answer. You just never know.

I'm aware that the generator/alternator shares it's gasket (p/n 36100, now 652072, also Superior p/n SA36001) with the tach drive housing. It's shown as item 9 in Fig. 18 (p. 32) of the C-145/O-300 IPC (Continental doc X30014), with the upper triangular portion for the tach drive housing.

But in Fig. 10 (pp. 18-19) of the same IPC for the engine, it shows another gasket (Item 32, p/n 641538 - still available/not superseded) for the tach drive housing. I assume that's a mistake in the IPC, and that only the joint gasket in Fig. 18 should be used. Would someone knowledgeable about this issue mind confirming whether or not this is a mistake in the IPC?

Never mind. I now see what's going on. Fig 10 of the IPC shows the "new style" crankcase cover assembly (accessory case cover). Figute 8 on the previous two pages shows the crankcase assembly cover with the same gasket (p/n 36100) for the tach drive housing as for the generator in Fig 18. So there's no inconsistancy, at least between Figs. 9 and 18. That's the trouble with looking at these documents electronically. I didn't page back far enough to get the real picture.
Sorry for the confusion.

If you are replacing the gasket for the alternator/generator and tach housing, you may want to consider replacing the oil seal for the tach drive, since you will have it off already.

Thanks Kurt. That's what prompted my question. I was putting a list together of the replacement parts I might need (including for replacing the tach and alt/gen oil seals while at it), when I saw those different gaskets in the engine IPC.

Anytime that gen/tach drive gasket is replaced the tach drive oil seal PN 642714 should also be replaced. IMO