Love those Bosch fast-start instructions!!

[Nate Stanley]

To those who have installed the Fast-start glow system on a w123 5-cyl Diesel , replacing the loop type glow plugs with the pin-style ones–

I want to do this to our ’79 300D.

So you buy this kit, and for 5-cyl engines there is a separate set of instructions from the 4 cyl application that tells you that you need to buy yet another relay to make it work.
This gives rise to three questions—

1) Does this mean that none of the 4 cyl instructions apply at all? (that part about slitting the harness was strange)
2) Assuming I only need to refer to the 5 cyl instructions, Is there anything special about this extra Bosch relay, or can another one be substituted?
3) If I need this Bosch relay, who has it?

Thanks to all who can help-

[CHAPP]

I wanted to buy the fast start GP's on my 123... but was told to go with what it already has on it... by a fuel injection shop that had both kinds??

[samiam4]

ChARR,

The gp's are the same in the fast start kit and current pencil style glow plugs. THe difference is the relay keeps the plugs on after starting. Behr and Bosch both make kits.

Nate,

I think thought the relay was the same(?). My post kit was for a 4 cylinder and I just purchased an extra plug. If you are replacing loop style plugs, then the only issue should be purchasing or making a wiring harness.

Michael

[Stevo]

Nate

I gota admit when I looked at the instructions for the "fast glow' system it was totally confusing as I am a little "wiring challenged" anyway. I consulted my local MB friends and they all just installed the new plugs and used there old relays. Thats what I did and it works fine. I just glow it for 7 to 10 seconds then fire it up. I am not sure I want the GPs glowing for too long after start up anyway. On my "79" 240D I have a push button using a solenoid for the series type GPs so I can be in complete charge of the glow time. If its cold I give a little more "after glow" but otherwise no. Be sure to disconnect the ground in the old system and changing the fuse to a 80 amp wouldn't hurt although I have not.

BTW The series GPs made a Big differance, you will love it!

[Nate Stanley]

Stevo,
Thanks for the input-however, since I have the new Bosch relay and have paid for it , I'd really like to use it. Bosch put in a post-start glow feature to help the engine smooth out sooner, and I don't see that as a problem.

The goofy things (for me, anyway) in the instructions are:

1) For the 4 cyl is the part where you are told to "dismantle the compensating resistor".
I assume that means to remove it, but in the 1979 123 body, WHERE IS IT? I can't tell from my Haynes wiring diagram what it's referring to.

2) then you are to slit the harness from the new cable assy and feed the green wire thru to the disantled compensating resistor.

If anyone can tell me the location for this, I'll be good to go-

Thanks in advance,

[Stevo]

Nate

Ya I know what you mean, as long as you payed for the relay might as well use it. I had to get on the road and I figured I can hook up the new relay when I figure it out. As a matter of fact a friend came by the other day with a 240D he just got and it has the upgrade with new relay so when he comes over next time I will look at his and do mine. I will keep the old relay where it is for a spare.

[Nate Stanley]

Stevo,
thanks for looking into this. I really hate the smell of burnt wiring--