Tachometer Problems

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Wed, 03/03/2010 - 08:17
lufc12345
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Joined: 06.01.2010
Location: Cromer, Norfolk

Could anyone tell me where the Tachometer or Rev counter attaches to in the engine? The tachometer in my car is very erratic, sometimes it works but mostly it doesn't, I have checked dial and the cables but all seems fine so I want to check the other end.

The car is a 1988 300GD, cheers

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Wed, 21/04/2010 - 21:15
#1
bushcraft
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Joined: 21.01.2009
Location: N Yorkshire
Re: Tachometer Problems

I read some place abouit a guy using a cig filter to get a better connection , at the clock end, or somehting lik. I'll try find the link..bear with me on this..its some place.

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Thu, 22/04/2010 - 13:28
#2
mgrays
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Joined: 08.11.2005
Location: Aberdeen Scotland
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Re: Tachometer Problems

Rev counter fix;
“on another diesel forum I found this trick known as the "cigarette butt trick" Someone unscrewed the tach sender unit, pulled the inner connection out(where silicone lies behind) and stuck a cigarette butt which gave better contact and solved the problem. I dont smoke so I used a piece of foam I had handy. I used that such that when you screw cap back on you can feel the pressure a bit. Photo 1 below shows the sender unit unscrewed off, the inner part (2) can be pulled from the cap portion(1) and there you would see the silicone stuff(meat and potatoes..ha ha). In photo 2 you could either cut, like I did a piece of rubber in a round way or use something comparable you may have lying around the shop ( rubber hose etc.) you would want something somewhat durable that will keep its "bounce" as I have used some rubber that "mashed" in time resulting in recurring tach problems. I woul love to take the inner part as in photo 1 but do not want to risk losing tach on this car, my 300SD, as I have not had to touch this one. Kind of weird as this car is 25 years old. Hope this helps, if you need more detail, please advise. “ Mike

from here;
http://www.pointedthree.com/disc/forums/showthread.php?tid=5047&posts=25...

It is pretty common it seems .. I wiggled mine while having an old car mirror balanced against the steering wheel to see the dial and it did kick into life at one point (as it does on the road). Never got a solid position or reason and the unit is not easy to pull apart.. so I have not so far pulled it apart to fix.

Let us know if you get better results!

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Thu, 22/04/2010 - 16:33
#3
fixwin38
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Joined: 09.07.2006
Location: northern ireland
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Re: Tachometer Problems

Hi the multi pin transducer that sits under the black screw cap on the edge of the n/s inner wing gets corroded...remove it and soak it in a half teaspoon full of bicarbonate of soda mixed with 4 teaspoons of water.... leave for 1 hour then rinse allow to dry for 24 hours in a warm 20/25c atmosphere..( top of a central heating radiator ) the "wedge" idea sometimes cracks of the corrosion allowing the transducer to work again...neither method is more than a 50% remedy.also check that you have a good earth to the transducer by running a wire from the negative post of the battery to the transducer earth terminal ( touch only ) ......

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