240D 1980 Body with a new 77 Heart GP Question
 

Well I did it. I took the motor and trans from my ’77, 240D and stuck it in a ’80, 240D. Here lies my problem the Glow plug setup is different. On the 80 there is a GP harness and I am trying to use it on the 77 motor. There is a plug at the end of the harness that has a plug on what I assume to be the GP Relay module, but the module is only Hot on one side and it is not hot on the side that operates the GP’s. Is the module Bad? The GP light on the dash steady blinks, but will not stay on like it did pre transplant. What do I need to do? I am assuming the relay module is bad. Can someone point me in the right direction to get the car on the road. Thanks in advance.

Does the 77 motor have the original loop plugs or upgraded Bosch 80035 pencil plugs?

I dont know? I would assume the original's as I am the only molester of this vehicle.

If it has the original loop plugs, the newer 1980 glow plug relay won't work.....the older loop plugs were fed with only one 12v power wire....where as the later relay has a separate power wire for each plug.....this means you would need to install the Bosch 80035 upgrade plugs and then you can use the 1980 relay and wiring harness.

Good pictorial on upgrading

http://dieselgiant.com/mercedesdieselloopglowplugrepair.htm

or swap some of the 77 wiring over.

Swapping the glow plugs for pencils would not only be easier, but the difference in starting power is tremendous. I've done that swap a few times and my only regret was not doing it sooner

A couple of questions
I just pulled out the large hole GP's out of the 77 donor motor. On the receiving 80 body there is a box with a plug connection for the GP's that has a harness with a wire going to each one of the GP's. Once the new larger 80035's get here can I hook it up the way is was on the old 80 engine, that has the smaller hole GP's. Will this work and make the glow plug indicator light work on the dash?

#2 at the end of the series of wires should there be a ground wire from the last GP to a ground?

disconnect the ground, and never connect it to any glow plug. install the new 80035 plugs to the 80 harness, and all will be well.

YEAH, Thanks:D