Tachometer/Cigarette Butt Trick

[benchracer]

Found earlier threads talking about using a cigarette butt to increase electrical contact in tach sending unit. What if you smoke non-filters?!

[David C Klasse]

THen smoke a pack of filters!! It would be good for you anyways! Besides, you should be anyways, those non-filters have got to be KILLING you!!
You can also try something other than a cigarette butt, that was just a common, easy solution. There are many other objects you could use. Good luck!

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[Edited by David C Klasse on 04-19-2001 at 03:04 AM]

[benchracer]

David,

Thanks for your concern about my health. My question was meant only as an attempt at humor, I really usually only smoke cigars and I figured a large cigar butt would be overkill. Anyway, I did try putting a cig butt in the sending unit and am very pleased that my tach works all the time now. I had traced the electrical connection a few months ago, suspecting that sending unit, but after cleaning
the connections, the tach still did not work. I was beginning to suspect the tachometer itself and am relieved that this simple, unorthodox method worked. Thanks to all who've gone before me on this.

[David C Klasse]

Benchracer,
I am glad it worked out for you! NOw if only that would fix my tach problem! Mine tends to stick a little when it's real cold outside.

[ejsharp]

I too have a jumpy tach. Precisely what is the cigarette but trick? Do you use the burning ember to heat up the sending unit?

Please explain.

Smiles.

[David C Klasse]

You should try a search for the specifics. I don't exactly remember, but I believe it is when you put the butt in the 'plug-in' under the hood. It puts pressure on the contacts, making them work. So a search to be sure!

[speedy300Dturbo]

Tachometer fix in detail here:

http://www.mbz.org/articles/electronics/300sd_tach_amp.html

I used a thick piece of cardboard and screwed the cover down REALLY tight. I haven't had problems since. In this case, tighter = better.

[william rogers]

a nice peice of dence foam cut in a circle about an inch in dia, and about 3/8 inch thick has kept my tach taching for months now, is really imbarassing for non smoking MB owners to be seen picking up cig butts off street.........
QWilliam Rogers....

[longston]

You can use a syrofoam packing pellet. Just unscrew the sender, remove it from the outer casing, and place the styro between the top of the casing and the unit. replace the unit, plug it back in, screw down the outer casing, and you're done. The reason that this works, is because there is a circuit board in the top of the sender with the soldered side pointed up. When you put packing in there, you both cushion it, and put pressure on whatever solder points have wiggled loose over time.

Sometimes, the pins that plug into the base come loose, and those will also need to be reglued

I really wish the originator of this technique had thought of something other than "butts", so we could call it something else...

BTW, before I had read about that "quick fix", I took mine apart, and resoldered the circuit board...

In fact, for too much detail on that subject, and a good laugh as TXBill (before he was a moderator) and I (when I was a new member) get into a little disagreement, and then make up, you can read this (somewhat embarrassing) thread in the archives:

New Info On The 300SD Tachometer / TDC Sender Problem

[Edited by longston on 04-22-2001 at 05:09 PM]

[SW]

I went to a junkyard this weekend and picked up a sending unit from an SD for $2.15. It looked brand new because the latex was white instead of yellow (like the original in my car). I plugged the "new" one in and the tach is back in action. $2.15 is cheaper than a pack of smokes and a new sending unit.

[william rogers]

I am glad too see in this throw away culture that there are
are still people willing to try creative ways of fixings things especially sometthing as grand as the 617 engine, wonder what the top designers of this masterpeice in Germany would think of the cig butt trick.......
William Rogers......

[savas]

Where is the tach sending unit located in the 300E? Is it where the diagnostic tool plugs in ?

Thanks