91 350 SDL Head R & R - Page 2 - PeachParts Mercedes-Benz Forum

GregMN · #16 09-19-2009, 08:06 PM

Thanks for asking. I installed the heat shields the way the old ones came out. The side that looks like a cone down. So the injector contacts the heat shield at the outer circle and the inner circle.

I hope that was the wrong way so the fix is as easy as that.

Thanks,
Greg

mplafleur · #17 09-19-2009, 09:34 PM

No, that was the correct way.

GregMN · #18 09-20-2009, 02:40 PM

Revisited the problem again today. I pulled the injector and honed the surface where the heat shield meets the pre-chamber. No change. I now think that the leak is between the pre-chamber locking ring and the pre-chamber.

Is it possible that the machine shop did not get the locking ring on tight enough?

Is it possible to get blow by there?

I have already returned the rental tools to Phil.

Edit/Update: After referring to the FSM:

Yes it is possible to get blow by there.

It is possible to refinish that surface with the head in place if you have the special MB tool.

The car starts, runs, and drives fine. It's just if you open the hood, there's this annoying sound like a collapsed lifter whispering. Maybe if I just drive it the gap will fill with soot....

I'll run it over to the machine shop next week and see what they have to say. I knew I should have just bought the pre-chamber tools....

There was a recent post with a photo of an injector, held up in a slip jaw pliers, with the pre-chamber glued to it. Now I know why someone tried to seal that gap. So they were not a stupid idiot, just a lazy one. It is temping...

GregMN · #19 09-30-2009, 06:20 PM

I'm done with the 300SDL conversion to grease. Now back to this project...

I am going to order the tools to pull the pre-chambers to better seal them to the head. There are 3 that are leaking.

In the mean time, does anyone have experience with a leaking pre-chamber that caused any harm. I would like to continue to drive the car while waiting for the tool.

Thanks,
Greg

GregMN · #20 10-14-2009, 06:48 PM

I got the socket to remove the pre-chamber retaining ring from MB for $27.
MB tool # 603 589 00 09 00
The MB tool to slide hammer the pre-chamber out of the head is $179, too much.
MB tool # 602 589 00 33 00

I bought a slide hammer at harbor freight for $20
I bought an injector out of a 220D at the junkyard for $20
I took the injector apart. The top 1/2 of the body threads into the bottom 1/2 with the same threads at the injectors for the 603.
I drilled out the connecting nut that came with the slide hammer about 1/2 way with a 13/32 drill and threaded it with a 12mm x 1.5 pitch tap.
Photo below.

Remove the retaining ring.
Install the injector body in the pre-chamber.
Screw the slide hammer onto the injector top.
REMOVE THE GLOW PLUG.
Then hammer it out.

No welding of nuts or cutting of parts. The only part that was "sacrificed" was the connecting nut for the slide hammer. And I am fine with that. The injector was not damaged in the process and it as good as it was before.

I did get a .03mm shim for the pre-chamber/head seal. That apparently did the job because the leak is gone.

So, the car is back in service. Every feature in the car works. The addition of the vegetable oil fuel system is done (link below). Less than $2400 including the VO system. Still needs tires and maybe a battery before winter (I gotta a couple weeks, maybe).

http://members.fortunecity.com/greglyons/1991_MB_350SDL/1991_350_SDL_WVO_Conversion.htm

Thank you to everyone who provided advice, either in direct response to this thread, or in other threads on related topics, on this forum.