You have diesel right? So your redline should be at 5000 rpm or lower. The 2 above gauges are from gasoline models that have different redline, while the last looks like from diesel. The whole system works on different principals. I know my 1987 diesel has engine speed sensor at the flywheel. Is yours having one as well?
The gauge will not work without a signal from the engine.

 

Yeah, the cluster in my 2.5TD looks like the bottom one with the tach going to 6K, but no actual redline indicated. I read somewhere that the true redline is 5100 for the 2.5 and there is no marking on the tach because the injection pump can't deliver enough fuel to over rev the engine. I have no idea of that is true though, nor do I know what the rev limit is on the other diesel motors...

And yes, you need a signal for the tach, and I'm not sure how you would add that to your car. I'm sure someone here knows though!

 

You probably don't have the engine sensor to run a tacho my friend.
I suspect that you won't have enough cables to power the gauge etc.
Probably going to be a bit of a big task to try to retrofit it.

 

Well, it seems someone has already done it

Look what i found:
http://tobulus.de/w124/dzm/index.htm

But it is all in German.. I don't know a single word in German lol :surrender:

Anyone could translate the important steps how he done it here please?

Also that would mean that any tacho going to a W124 and with 6k RPM end on it could be retrofitted in my car?

Marky

 

It is possible to swap such tacho to your car. Someone in my forum did it in a proper way, and it works Each tachometer with Economizer is from gasoline engines and it is rather difficult topic to be done properly. The best way to do a swap is to find donor similar to your w124 and get the tacho from it.

You don't know German? Yes? So have you been trying to use Google translator ?

 

So a tacho from a 250D with the 6k RPM max on it should work right?

I tried the google translator ofc but its just a bunch of boo and doo, still cant understand shite

So still need some help with that :surrender:

Marky

 

So a tacho from a 250D with the 6k RPM max on it should work right?

I suppose it should

I've got that text translated to Polish but it is a lot of work to translate it to English.

In know that you have to take out generator and you have to dissemble it. Inside there is a red ring with roll between two half's of the generator. That ring has to stay on the back part of the generator because it's connected there. If you look at it you may notice that roll are/is soldered with 3 wires to a plate. And you attach to one of that wires/points.

There is much more info about it.

They say that there are two types of tachometers and they do not really say what's the difference. I think you should find someone with good German and ask to translate it for you. I suppose it is the best solution.

 

Google translation is always tricky. Translation from German to Polish comes usually better, since those languages share some logics, while English using different logic from words with different meanings will chose the incorrect one. Don't know about Hungarian.
I will take a look at this German site later today. I know several language, but only few hundreds words in German.
First thing to check is if the 200D is having electronic idle control with speed sensor at the flywheel. On my 300d the sensor is bolted on driver side on the oil pan extension.

 

This is the sensor I bought for my 300 and if equipped the 200 very likely has the same thing. You will see a bolt clamping it to the bell housing and wire going up to the main harness.
Turns out I did not need this sensor so if anybody needs one, I have it for resale.
Mercedes OM603 Crankshaft Position Sensor 1986-1987 300D 300TD diesel | eBay

 

I did translate the German page and it confirm what I could figure out with my limited German and pictures. Those cars did have option of tachometers, what was very expensive at the time and 1 was using sensor like I posted above, the other had Hall sensor on one of the pulleys.
The author used the ... 3rd option what uses alternator signal before voltage regulator, but that require high skill not only for installation, but even more for calibration. Even over the years I become good in electric stuff, I don't think I would risk my time to try this. So IMHO if you find the sensor on your car than you can find the gauge from identical model and that would be plug in montage. Otherwise you are running into prototype type of wiring.
Even the German author had incident when a short burned everything. .. he/she blame spouse....

 

Well finding a 200D here with that equipped is close to impossible.
But almost all 250D's have them.

So if i do buy that almost new looking one from the 250D, i would have to do the same stuff as on that german site i linked?

Or what is/are other options to make it work?

Thanks,
Marky

 

Find out where the engine sensor is (it's on the rear of the engine). If you have the electronic idle control then you most likely have the sensor as well. Shouldn't be hard to connect it to a 250d tach, or better yet snag a 250d harness for the tach.

When using the rear sensor you shouldn't have to open up the tach like on that german site. That was to change the number of pulses per rev, since the diesel tachs are tuned to the rear sensor with alot more pulses than the alternator or front crank pickup.

 

I think this wil clear things up.

According to epc the part number for the harness would be A1245400434.

 

Thanks for the pdf
Trying to figure out what are on the pic's..

When i was looking for the harness, found this:
A 124 540 04 34

Is the first photo there of the thing i should look for?
Or is what he did.. another story?

Marky

 

The pdf shows the tachometer with Hall sensor the German is mentioning on his page.
Looking at the picture, that system is using the same components that were used on W123 and the tachometers on W123 were famous for failing.
How much you really willing to put into this project?

 

You need to locate a four cylinder tach, and I believe the diesels require specific versions which are different than the gassers, because the impulse readings aren't the same.

 

The crankshaft front sensor should be the same for the gassers and diesels, but the diesels will need a different tach and tach amp.

 

As i said, a tach from a 200D here is close to impossible, or costs around 150$ used that 1 which i found.

Wouldn't the one from a 250D work then?

I'm prepared to work on its electronic's.. rather doing that than paying 1/4 of my cars total cost

Marky

 

If it's from a OM602, I can't imagine any problems. From OM605, I'm not too sure.

Have you consulted the EPC?

 

OM602 is a five cylinder and OM601 is a four cylinder. These tachs are configured for the number of cylinders. You can't use a V8 tach in a six cylinder and so on. I suppose it's possible to acquire a converter from the likes of Dakota Digital, but dunno for sure.

 

The number of cylinders could matter with gasoline engines, where tachometer takes signal from the ignition. Diesels have sensors on the flywheels and number of cylinders doesn't matter. The Hall sensor might be the easiest to fit.

 

MB certainly doesn't make this easy, since they just put a flimsy paper tag on the back denoting which tach is in the cluster. I have about a dozen 201 and 124 tachs, and most are missing this tag. What I was able to glean is that the gassers are 350Hz and indicate the number of cylinders, but both my five and six cylinder diesels just say 400Hz and Diesel, with no cyl reference. This might indicate that a diesel tach will work with all 4/5/6 diesel engine variants. Might be worth a try.

 

Alright, top stuff!

I will try and buy that tach from the 250D, well its 13$ anywayz.

Still couldnt find any sensors, i have been working around the car the whole day.

Could someone take pictures of the possible sensors i could wire up the tach?

Would be very appreciated

Marky

 

Here's the hole for the rear sensor.

 

Anyone saved that german page by any chance?

Finally got around doing this, cable already fitted into the generator and already have a proper tacho in my dash.
Just that i need to modify the electric panel of the tacho so it accepts the signal from the generator..

Anyone?

Thanks in advance!
Marky