Tacho drive leaking

[georgem]

Good morning,

I have oil leaks - more like a flow - coming from where the tacho drive cable  attaches to the engine. I have tried to tighten the silver collar nut but this hasn`t helped. I imagine there are some rubber "o" rings or flat washers in there to seal it.

So before I start pulling it apart - can someone point me to a schematic of whats inside or where I can get a sealing kit (if there is such a thing) ?

Thanks

[Pawel66]

Have you checked this one:

https://www.sl113.org/wiki/Electrical/RevCounter#TachBushing

Or the search on the Forum - may have clues there as well.

[georgem]

Pawel,

Spot on - thanks for helping.

[Charles 230SL]

George, the link provided by Pawel provides an outstanding break-down of the parts that make up the tachometer drive.

There's (2) rubber seals that eventually leak on the tach drive after a few decades; one is an O-ring (621 997 0040) that seals the 22mm fitting, and the other is a seal ring for the cable itself (great description by 66andBlue here: https://www.sl113.org/forums/index.php?topic=13061.msg88712#msg88712).

The seal ring is MB part number 007-997- 7346: https://www.authenticclassics.com/Seal-Ring-for-Mercedes-Speedometer-Drive-p/auth-008887.htm. Here's a link/picture of the 22mm fitting seal: https://www.authenticclassics.com/Tachometer-Drive-O-Ring-Seal-fits-230SL-other-p/auth-008961.htm. I needed to replace both of these seals on my 230SL about 3 years ago...vr, charles

[georgem]

Thanks Charles,

Are you sure about the seal? - it specifies its for the speedo and my problem is the tacho at the engine. Its definitely different to what Pawel66 showed.

Just asking.

[Pawel66]

The seal PN shown in the Technical Manual (the link I provided) is A1202610080 and was replaced by A 115 274 00 60. This replacement part availability is not defined at Mercedes - but we know from previous posts and experiences that it is NLA.

As this issue of leaking tacho drive is occuring time to time, the Members figured out that

A1152740060 can be replaced with A0079977346 - this seal is for gear box speedo drive indeed, but is good also for the tacho drive.

Charles is providing the numbers and links to post that talks about it.

Further on - the part number A0079977346 was further replaced and if you order it today, you will get part A 007 997 73 46 02.

I suggest you check the Mercedes dealer for all these parts, there may be no need to have them shipped from the US. I think Charles provided link to Authentic Classic so that you can see the part on the picture.

[ja17]

It is difficult to change this seal. In the old days, you could get a new fitting with seal already installed for a few dollars. I think they are no longer supplied this way.

[Pawel66]

It is, actually, available, part number A 127 060 00 46, here it is 72hours availability, costs about $100. As per the parts list it does contain the seal. But I see it for 113043 and 113044. I do not see this part for 113042, it is there for engine 127984 only. But this must be some mistake there.

Perhaps the reason why this seal is NLA is that they want you to buy the whole fitting.

[stickandrudderman]

Changing that seal is not that easy; I turn the old one out on a lathe.

[georgem]

Just to add a few more pieces to the topic and ask yet another question.

I thank everyone for the great advice so far - in the end I bought a complete kit from SLS - - top fitting which has the seal installed, thrust piece and tacho cable drive and "O" ring. My only challenge with swapping these parts is that the tacho cable drive originally was a push fit into the vertical timing gear - the new one comes with a thread - I`ll get it drilled and held with a roll pin - I was initially going to epoxy it in but figured the pin would be for keeps..

I am curious though about the vertical timing gear - at the bottom of this shaft is a slot which fits into a tongue which, I assume,  gives it its rotation BUT....why does it have a cog about 2/3rds of the way up - it doesn`t seem to mesh with anything.

Any yes, If you are wondering, I did have to extend the house mortgage slightly  to buy the kit but other than the thread/push fit issue - they are perfect replicas and well made

[ja17]

Hello George,

The cog at the bottom drives the oil pump. The whole vertical gear is driven by the timing chain via the horizontal timing gear which drives the vertical timing gear. Good thing you did not need the timing gears themselves, or you would have to get a second mortgage on the house!

[Benz Dr.]

I had one do the exact same thing and I found that the vent line running over to the throttle body had become plugged with rust and other crud. Since it was also cold out, water vapor had also frozen in the line making it worse. 230SL has a metal vent line while updated lines are now plastic so rusting is no longer an issue.  Any crankcase pressure will force oil out through the easiest means and the tack drive is a ready place.

[georgem]

Thanks Joe and the Dr,

The cog I refer to can be seen clearly in the last photo of this old thread.

https://www.sl113.org/wiki/Electrical/RevCounter#TachBushing

The shaft is about  9cm or 3.5ins long and about 12mm or 1/2in dia. It withdrew easily and I cannot see any corresponding cog in the hole that it came out from. A slot at the bottom of the shaft marries to a tongue(?) that is at the bottom of the hole. What is the gear for?

[georgem]

Woohoo- hold the press and disregard my last!!!

I had a closer look down the "hole" and there is definitely a cog on a horizontal shaft for the tacho shaft to mesh into - ho hum, as my wife would say, I should have looked with girls eyes

Sorry for any confusion

[Desertpagoda]

Since we are on the dist/oil pump drive subject.....dont forget about the bushing in there that controls the up/down movement of the driveshaft, if it is neglected and wears too far, the oil pump stops and the engine is destroyed. PN#126 180 0044

[georgem]

Hey Thanks Desert - I replaced all components of the drive mechanism inc the thrust piece so the end float is spot on - I didn`t measure it but I used my calibrated hand and it moved up just a smidge so all good.