Datsun Roadster Forum-311s.org

The fun with oil leaks never ends. Found that my tach drive was leaking and dripping oil down the block and under my engine. I found this on the advice of one of our local gurus. Okay, fine, time to pull it out and change the seal inside that I knew nothing about but was educated on.

If only it was that simple. There are two tach drives of course, the early one and the later one for high cars. The early one uses an O ring inside to seal the shaft. O rings... get hard and leak and Nissan changed to a seal in the later ones for good reason. And of course the seal will not work in the early one. The later drive's outside diameter is larger, has metric threads, and uses the hose oil line to the base. So not very easy to change.

The kit I bought for it from Dean is only for the later one and there is no kit for the early one. Well I'm not going to let that stop me. The early one's O ring sits inside with a bushing holding it in place between it and the housing. So I figured if I pulled the bushing out the seal would fit. Nope, diameter still too small. So I measure the seal and drilled the housing out with a 5/8ths bit. I had ruined the seal trying to get it in earlier so had to wait for new one. The local guru to the rescue, texts me and has a base, drive and two new seals. They're a standard seal 10x16x4mm.

So I check the later one and it is a few thousandths larger than the one I drilled out. In goes the new seal for a perfect fit. Old drive with new seal and no more drip. Screw the leaky O ring.

Good to know

Some photos I resized.

The two seals.


The early drive with the bushing removed.


The early one with bushing and later one.


The early one on the right with new later seal in it.

Somebody has to pioneer the changes eh? Only it sucks to be the pioneer sometimes! Hang in there Curtis...

I was told that only the U20 uses the hose. Have to see if the later 1600 base has the same oil line thread.

50+years later these cars can surprise and confound both owners and experts! LOL.

Curtis wrote: Mon Aug 09, 2021 8:52 pm I was told that only the U20 uses the hose. Have to see if the later 1600 base has the same oil line thread.

IIRC, I bought the later 1600 base and pinion drive and it uses the same oil line as my '66. I purchased for the same reason, leaky early seals. No leaks since the change 6 years back.

Picked up a used 1968 1600 base yesterday. Oil line thread the same. Of course has the new style seal and is metric for housing and distributor hold down screw/bolt. Also got a really nice distributor.

So I learned the U20 oil line is tubing and not hose and has different fittings. Hose is the oil gauge line.