tach in 240?
 

is the redline the same on the 300Ds and the 240?
how hard would it be to put a tach in the 240?

Tachometer
 

The 300 is a 5 cyl (Tach sensor takeoff is on the front of the crank pulley)

The 240 is a non-turbo 4 cyl ( you would need to "cobble" together a working
sensor apparatus)

Think of the 240 a a low speed Diesel (IT'S Not) compared to the 300 !

Yes compress is correct... 240D's did not come with the magnetic sensor mounted next to the center pulley, and this sensor is supported by a bracket which is bolted INTO the block... therefore it is not recommended to start drilling holes (3) into the block to retain the factory bracket... and this is just the beginning... it's a tough project, but not impossible... :(

If you're really desperate, I saw a seller in Ebay Germany who has devised a way of installing tach's on w123 diesels that were NEVER equipped with this option... it's ingenious, AND his price is steep!! :eek: ...take a peek: W123 VDO Diesel-Drehzahlmesser Mercedes W 123

I heard of someone using a simple optical timer from radio shack that you mount onto one of the pulleys. you then calibrate the LCD display by measuring the radius of the pulley. Once done the timer just counts how many times the white dot comes through its field of vision per minute and you can mount inside the car. crude,but apparently effective. not sure if this can be done in MBs but I think i remember this works on older VWs. supposed to be pretty simple. at one point I was thinking of doing it, then i realized it doesnt matter, just drive the 240 WOT and it doesnt really care :rolleyes:

tiny tach
 

65 bux, minimal install

tinytach.com

Wait, I thought they both had the same stroke/bore? Why would the 300 rev higher than the 240 then?

That tinytach site looks REALLY cool, I might have to go order one for my 220.

I believe the tinytach has a delay in its display though its a few seconds or something so I'd think that would be annoying........maybe someday I will figure out how to get my tach working again.... :o

Is it that tach amp? I can keep my eyes peeled for them out at the boneyards... I have one I need to mail to someone, but PM me if you want me to nab you one. :)

Do a search on 240D tachometer, look for my name....

you have an '83 240D, it has a tach sensor the EGR system (my '82 does, and 82-83 should be alike...). you **might** already have the appropriate hole/mount for a 300D tach pickup. I have not seized the opportunity to compare the two yet.
I do have a 300D tach, and tach amp, and if the wiring works right, I'm gonna try to pick up a tach signal off of the EGR tach sender wire (its the only coaxial wire and connector in your engine bay, driver side) If I get around to it this summer.

-John

Nope, my tach amp is brand new and so is the gauge pod, still not a quiver out of it....and there is voltage at the cable that plugs into the pod....13.4 at idle, just like it should be....just, no rpm readout. :o I suspect the crank sensor....but its $60 so I will have to build up to ordering one....

Ah, well I tried if it was inexpensive to repair. :D

C'mon John, hurry up and do it, and post a complete how-to so that all the 240D people can have a tach!

They say it updates once a second. I went ahead and ordered one (my 220D doesn't have a tach to fix) - would be nice for setting idle speed. Plus, with my speedometer being all wacky I could more easily figure what speed I'm *actually* doing.

is that the wire behind the glove box I thought was an old CB antenna(sp?) :confused:
what is a transducer and what size do I need

I wouldn't worry about any redline, there isn't a red line on the tachs in either of my diesels. They are mechanical injected enignes. The engine's rpms are based on how fast the pump can, well, pump. So you really can't over-rev a 240 or 300 engine.