If you have a 240D with EGR like I do, it is very easy to retrofit it with a tach/clock from a 300D turbo. Mine is an 83 240D w a 4 spd manual. I feel it needs a tach more than my 300D automatic so I borrowed the tach/clock from it till I can find another one. I tested the tach with the EGR controller on the floor of 240D on Sat to make sure everything works and installed it on Sun. It's working great! I thought some of you 240D lovers may like to add a tach also thus this DIY. If anything in this DIY is unclear just ask.

You will need to get a working tach/clock from a 300D cluster (not the entire cluster!)

1. Remove passenger side-kick panel and remove the EGR controller mounting hardware (3 bolts).
2. Remove the 4 small screws that secure the EGR controller cover and pull out the board.
3. With a DVM set on AC scale, probe the 2 points where the red and black wires are soldered to the board while engine is running (see pic below). Be careful you don't short anything out! At idle you should have around 0.2 volt. Reving the engine should increase the voltage to near 1.0 volt. If you have voltage there, then your EGR controller will work as a tach amp and drive the tach. All that remains is to feed the signal from the EGR controller to the tach and supply power to it.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

This is my modified 240D cluster. The only change is replacing the clock with a tach/clock from a 300D turbo and adding 3 wires. The long red wire is soldered to a rivet on the left side of the cluster as shown. That rivet is supplying switched +12V to the tach (upper terminal on tach, right side of pic). Ground power is through the tach metal back plate so no wire is necessary. Since I did not have a connector to fit the tach, I used a female barrel connector which fits the terminals on the tach and just soldered the wire to it. The fat black wire with a short red pigtail goes to the EGR controller. You can't tell from pic below but it is a twisted shielded pair (red/blk with black outer jacket). Red goes to the lower terminal of the tach, black is ground and is conected to the tach's metal backplate by using one of the screws (not visible because the screw is behind the cable). This wire pair brings the amplified signal from the EGR controller to the tach. If you do not have shielded twisted pair cable, just a twisted pair will do IMO.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Here's a pic of the modified EGR controller with wire sticking out (right side of pic). See first pic for soldering points.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Here's my working tach in the 240D. It was a really easy job. How do you like it?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

i wish i could have done that to my 240D, but i have a 1980 without a EGR. i guess the only way i can have a tach on a manual 240D would have to be an engine change?

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

Funola-

Thanks for the writeup. That looks like a worthwhile mod. Even I should be able to do something like that.

Rick

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

Looks great, and very stock. Did it require any calibration? It seems to read high if that shot is at idle...

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

That looks great, it always seemed like something was missing on the
right side. but then Iam use to a tach.
There are always great minds at work on this site.

Now you need a 160 MPH Spedo.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Engine change just to get a tach? No!

You could go to a pic-n-pull and get the mag pickup, EGR controller and harness from an EGR equipped 240D and install it on yours. You have to verify that you have a "tooth" on your harmonic balancer for the mag pickup to sense. If it does not have one, you can always make one by epoxying a "tooth" on the harmonic balancer by using a small allen head screw.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

You're welcome! Anyone who can solder and turn a screwdriver can make this mod.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Thanks! No calibration necessary. I had my foot on the accelerator when the pic was taken.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

It's a great and clever mod...you should get it posted to the DIY articles section for posterity.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

How do I do that?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I found a metal box behind an opening on the passenger kick panel, here's what it looks like. Is this my EGR computer? Its from a euro, if that makes a difference...

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

I thought Euro's don't gaive a damm about EGR so my guess is no.

edit:

See if there's a LM1815 chip in there. If so, you maybe in luck.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked