Tachometer Cable question

[Ed Riefstahl]

Greetings Pagoda friends,

A few years ago (more like 10 or more) I developed an oil leak that turned out to be the seal where the tachometer cable attaches to the the engine. I purchased a new seal, but could never manage to remove the unit on the head that drives the tachometer.

I find it hard to believe that head removal is required to unscrew the unit that drives the cable. However I've tried to remove it several times, but the head is in the way enough that I can't get a socket on the nut. I disconnected the cable and capped it off, so no more oil leak. It's been that way for years. I sure would like to have it work, but will not remove the head.

Does anyone know if a special tool is required to remove this unit? I may try to make a tool to remove it. I'd sure like it to work before our cross country road trip next summer.

Any suggestion are greatly appreciated.

Ed Riefstahl
Erie, PA

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - One of 1000, (have you ever seen one?)
1997 Ford Ranger step side (Mater)
2023 Mazda CX 5

[Charles 230SL]

hi Ed, I had the same problem when I changed the seals on my tach drive. Its been a few years but seems I ended up using a 22mm open end wrench. If you don't have a 22mm wrench you may be able to get a crescent/adjustable wrench in there.

[rwmastel]

Ed,

You're saying a 22mm socket wall is too thick and hits the part of the head that surrounds the tach drive?  Maybe Charles has the answer.  Also, it was demonstrated to me by JA17 this summer that high quality socket sets are made of better metals and therefore can have thinner socket walls.  Sort through your stuff and see if a different socket works (if the wrench doesn't get the job done).

For further info on the very important parts below the tach connection, click here in the Tech Manual:  https://www.sl113.org/wiki/Electrical/RevCounter

Scroll down to "Tachometer Bushing, Removal and Replacement" section and look through that.

[Ed Riefstahl]

Hey thanks guys,

I'll take a look at it again. We're in the middle of grape and fruit at the moment. So it won't be for a while, probably during winter.
I think that link will be very helpful too.

Ed Riefstahl
Erie, PA

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - One of 1000 (have you ever seen one?)
1997 Ford Ranger step side (Mater)
2023 Mazda CX 5

[mmizesko]

Ed,

If you haven't replaced the oil pump Thrust Piece on the oil pump, that the tach cable feeds into, you should.  the brass wears and will eventually render the pinion gear useless, any your engine might be ruined.    Here is a link to instructions:

https://www.sl113.org/forums/index.php?topic=4869.msg30379#msg30379

https://www.sl113.org/forums/uploaded/ja17/2006126191530_Verticle%20gear%20assembly.jpg

Mike Mizesko

[ja17]

The 22mm fitting must be removed first. After that the special 10mm set screw holding the large thrust bushing in place, must be removed. Next, the aluminum thrust bushing can be lifted out of the block without removing the cylinder head.

[Ed Riefstahl]

Hi Mike,
Thanks for the valuable information and links. I actually printed off the exploded view / diagram. It's definitely more complex than I originally thought. Several years ago I ordered a new seal and thought I'd just remove the top and replace the seal.

I plan to check it out during the winter months, after fall harvest etc. I haven't found a place to purchase a new "thrust Piece" yet. So, if anyone knows where to purchase this part or a rebuild kit etc. I'd sure appreciate that information.

Joe,
I sure appreciate your suggestions on how to remove the unit.

is there any reason to replace the thrust bushing it there is no significant wear / play in the bushing. Or, am I to expect it? If this is the case, I'm not sure I want to remove it until I have a replacement.

Is there any real danger in leaving it disconnected and capped off as it has been for 10 years? I plan to take a 6-8000 mile road trip next summer with Ms Magoo, and really don't care all that much if the tach. works. If it's something I need to address, before the trip, I'd sure like to know.

Thanks everyone for your valuable comments and suggestions.

PS: If anyone lives near Erie, PA, or has family in the area, I have about 1/2 acre of Concord grapes left on the vine. They are primarily jelly, juice or wine grapes, however they are wonderful table grapes too.
The grapes will fall to the ground soon and are FREE to anyone who wants to pick them.

Kind regards,
Ed Riefstahl
Erie, PA (North East)

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - One of 1000 (have you ever seen one?)
1997 Ford Ranger step side (Mater)
2023 Mazda CX 5

[ja17]

You won't hurt anything leaving it disconnected and capped off.  Also you can shim the thrust piece to reduce play if excessive.

[Ed Riefstahl]

Greetings fellow Pagoda friends,

After two more major spine surgeries in 6 months, the last was 5 weeks ago today. I'm almost back to normal function. However, I'm not sure I'll be able to work under the hood of a car for a while. That being said, we are still planning our cross country road trip in Ms Magoo (1966 230SL) this summer. Maybe 4-6 weeks on the road.

Is it possible to check this tachometer thrust bushing without removing the unit from the head? I'm not one to take shortcuts, but sometimes its just necessary. I can live without the tach, no big deal, but am I asking for trouble? Maybe it's easier to remove and address the bushing than I'm thinking. For 10 years the cable has been unscrewed and the unit is capped off to prevent oil leakage.

The tachometer bushing is about the only thing that I can think of that I've not addressed. Here is a condensed list of what we have addressed in the last 24 months.

Complete new cooling system including radiator. R & R rear differential / axle, install re-manufactured automatic transmission, u-joints, and center support bearing. Replace all rear body and suspension mounts. Replace motor mounts, shocks and sway bar linkage. Complete new braking system, front to rear, including master cylinder. New alternator & new starter. New fuel filter & changed fuel injector pump oil. I also have a new set of white wall tires I plan to put on this spring.

Please feel free to make any suggestions or comments. if you feel I've overlooked something in the list above, please comment. Sometimes I miss or forget the stupidest, little thing. I do plan to take a spare fuel pump on the trip.

Kind regards,
Ed Riefstahl

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - One of 1000, (have you ever seen one?)
1997 Ford Ranger step side (Mater)
2023 Mazda CX 5