Hi guys, first time caller, long time listener.

I have a '78 300D with NA engine, and I would like to fit a factory tacho in place of the clock.

I have done a reasonable bit of research on this subject (this forum especially), and so far my conclusions have been that it will not be an easy task (especially over in this part of the world).

However I came across this thread:
http://www.peachparts.com/shopforum/diesel-discussion/341652-quick-fix-85-w123-tach-c-after-egr-failure.html

Which has given me an idea, Is it possible to shortcut the crankshaft balancer pickup, pricey tach amp and rare 2 pin tacho, and simply install a 3 pin tacho (ie from a EGR equipped car) and hook it directly to an EGR computer flywheel sensor?

I swear I remember seeing some sort of removable inspection plate on my car by the flywheel either on the bell housing or on the engine. It would be ideal for mounting a sensor on - it would take some work mind you.

Do-able?

Thanks

Definitely doable - provided you can find a way to mount the sensor on the intermediate plate such that you can get a signal off the flywheel teeth. If you can do that, the rest is trivial.

The clearance needs to be pretty close - use the thickness of a credit card as a guide.

If it can be pulled off, this would be an excellent solution for the rest of the users that don't happen to have access to an '85 version with that setup standard.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

so... does your car not have the front balancer pickup on it?

and what part of the world are you in?

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I'd venture he's in New Zealand...

__________________
[/SIGPIC]~cirrusman

1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang"
[SIGPIC]




1983 Toyota Tercel (Tommy, The little Toyota that could)
1965 Ford F100 (Grandma Ford)
2005 Toyota Sienna (Elsa, Wife's ride)


Gone:
1988 Toyota Pickup
2004 Subaru Outback

1987 Cadillac Fleetwood Brougham
1986 Volvo 740 GL Station Wagon - Piece of junk.
1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P.
1987 Pontiac Fiero GT

Ok, that's a a good start.

My thoughts too.

Cheers

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

It has the little pin on the balancer and some sort of mount I think but no sensor (just the other day I had a look while viewing the carnage after the water pump pulley flew off, but that's another story). I would rather not go through and install a stock system if I don't strictly have to, since I would have to buy from USA for all the parts pretty much.

New Zealand. W123s aren't all that common over here...although there is an '85 230E for sale along the street a bit

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

Haha, you're onto it!

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

You should be able to use most any VR sensor if it's more convenient. They are used as crank position sensors, timing sensors (as in the Ford EDIS system) speedometers (MB has them in the tail cone of electronic speedo cars) and so forth. You can get really creative.

Here's a setup I used on my SL conversion for awhile to provide the signal for an electronic speedo when I had a transmission with a mechanical pickup installed.

Here is the mount I fabbed up for the VR sensor



Here's the mod I made to the driveshaft to make it into a "trigger wheel".



You'll figure out something creative I'll bet.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Awesome, so I'll try grab a sensor built into threaded rod then which would make life much easier.

That is a neat setup you made there. Good to know I'm not venturing into the "land of unknown" like I thought I might be.

Hopefully I can just drill a hole on the plate at the exact spot and have nuts on the sensor either side of the plate to secure it in place. Maybe add a cover of some description to stop tall grass etc damaging the sensor/cable.

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

Yes, if you can find one with a thread configuration, it would be pretty easy to turn it down until it hits the flywheel teeth and then just back off 1-2 turns to get the desired gap. Check the Ford EDIS pickup. It's pretty compact and while it isn't threaded, it has two mounting ears that could be adjusted with shims (washers).

Keep us posted.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Uh well I've bought both an '85 300D tachometer and a couple of sensors (they come with one nut each, and the thread is a weird type so I thought getting two might be a good idea).

Now just waiting on shipping.

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

I put an MD tach in my '84 6.2 Blazer, while the motor was out I mounted the (MB) sensor (with homemade bracket) (on one of the water pump mount bolts) "close" to the harmonic balancer. The slot on the H. B. causes a disruption in the magnetic field & the sensor detects it. Just cant use it for timing engine, tho.

Time for an update.

I have got both the '84/'85 tachometer (probably the only one in New Zealand ) and a couple of VR sensors, which are threaded.

I have taken the inspection cover off on the engine by the flywheel and made a trace of it on paper, some time I'll get around to making a new plate with a hole in the the right place.

The other thing is how to wire it...the sensor has a green wire and a red wire. The tach has a W pin, ground and + pin. I assume the + is meant to have a 12V feed to it? Does the red sensor wire go to the W terminal and green to ground? Then again if the VR sensor is just a coil I guess it doesn't have a polarity as such?

Cheers

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

The white sensor wire goes to the green tach wire. The others go to ground. At least that's the way I translate the jumpers to the color coded wiring diagram. I don't believe it will work the other way.

Let us know what you find. It's just a signal so hooking it up backwards shouldn't harm anything.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

There's no white wire on the sensor - only red and green, and no tach wire, I never got a wire harness with the tach

Guess I'll just have to play around with it when I get the plate made up.

__________________
1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD