Getting the tach gen dog out and then in again

E-Type
1

A week ago I was doing a fast pass, downshifting and stepping on it. I then heard a noise. I looked down and my tach had stopped working. Not a big deal. A little later I saw smoke in my rear view mirror. It’s a British car, a little deal. THEN my clutch started to slip. BIG DEAL. Rear main seal? $XXXX? I headed for home.

At home I noticed a lot of oil coming from the back of the engine and fire wall had a lot of oil. So I did one of my most hated jobs - removing the tach generator. When I removed the TG, I noticed that the whole inside of the TG was gone, leaving a nice hole for cam shaft oil to leak out and drip down onto my transmission and apparently onto the disk.

Once the TG was out I decided it would be good practice to replace the TG dog. It took about 15 minutes to remove the wire clip that holds the dog in place, but after another maybe hour of trying every tool in my garage, I couldn’t get something in there to pry out the dog.

I finally invented, soon to be patented and sold in the for sale section of the forum was a custom made, back of the engine, tight space, 4.2 L dog pry bar.

Dog tools
Dog tools2045×1845 914 KB
I’ve also included a shot of the initial step dog installation tool. Finger not included.

Now I thought this would be enough, but the dog won’t fit nicely in the back of the cam. I got it about in the right place and using my other hand was able to rip off the dog from my super glued finger leaving forensic evidence (the tip of my finger) that I alone did the repair.

Then I was once again stuck with trying to push the new dog into the back of the cam. I finally took a long socket and placed it on the dog and then using a pry bar against a pad on the fire wall was able to push the dog into the cam. I then switched to a smaller socket to get it all the way in and allow the wire clip to be reinserted.

Dog insert
Dog insert3024×4032 3.16 MB

I hope this is helpful.

2

It is (was) and my tale was similar, and the original dog just fell apart. Made of some kind of plastic or nylon? Anyway, all I needed was a new dog, and it came to me that the yellow plastic on a screwdriver takes all sorts of abuse when hit with a hammer and used as a chisel. So, I simply took a hacksaw and sliced myself a piece off a stubby philips and then used the old pieces to make a pattern. A file and some patience yielded a new dog, and it ran right up to the time I sold the car. Improvisation goes a long way…

3

You learn something new everyday. Of all the cars I’ve dug into that had the tach generator none ever had the circlip, so I never knew! Always thought the generator kept the dog in - and it does.

1 Like
4

I don’t want to rain on your parade or ruin your sleep, but I had one of those aftermarket nylon dogs installed in my car. It lasted a couple hundred miles and then it detonated. The tack went to zero, and worst of all, the bits dropped down the oil return and that led to a day’s work pulling the pan and digging out plastic bits and trying to reassemble it to make sure I had it all out.

It’s really not up to the job, a poor substitute for the original rubber bonded metal one. They are NLA but some places have some NOS ones on the shelf. I got one from East Coast Jaguar off of Ebay. I would never install another nylon one. A new original one should last for decades. I’m surprised they don’t at least make reproduction ones out of brass.