Removing Injector Crush washers - PeachParts Mercedes-Benz Forum

willjayc · #1 03-15-2008, 03:14 PM

I have a 1977 MB 300D and I took the injectors out for servicing. I can not seem to get the heat shield (crush) washers out of the prechambers. I've done this job at least 3 times on a 79 240D usually without any problem. (I have a great bent pick for getting them out.) After closer inspection it seems to appear that the hole under the injector is all one piece, nothing will budge, have cleaned them up and can't seem to find a seam anywhere. Also, when I thread the injector back in there are no threads showing above the pre chamber. On my 240D I can see a bit of thread and the 300D injectors, when I put them back in seem to seat deeper. Is it possible that there were no crush washers in there? The Prechamber seat (where the injector seats) has a bit of a profile (slightly raised centre)but does not appear to be the same profile as what the top of my crush washers look like .

Basically the new crush washers have a 1/16 to 1/8 raised ring on the outside edge and the existing injector seats do not . However the centre is raised on the existing seat as is the crush washer.

I really can't tell if there were any in there? Any advice?

I am really leaning to the fact that there were none or this engine is different than my 240D and doesn't need any?

Any Help greatly appreciated!!!

Will

1979 240D 340,000 KM 60,000 on WVO Trusty but Rusty!
1977 300D 249,000 KM Awaiting conversion

toomany MBZ · #2 03-15-2008, 03:18 PM

There may not be one in there, I would put one in, torque down, and see if it leaks.

DeliveryValve · #3 03-15-2008, 04:09 PM

Quote:

Originally Posted by toomany MBZ

There may not be one in there, I would put one in, torque down, and see if it leaks.

Take a look at the soot/carbon on the end of the fuel injector. Now take a flash light and point it down the pre-chamber. If internal hole is the same diameter as the soot/carbon mark on the injector, then the crush washer/heat shield is still there. If the hole is bigger then you don't have any heat shields. I wouldn't just put in the heat shield and test it as is, you need to investigate visually a little more.

If indeed there is one in there, it is mostly glued in there by the carbon deposits . Get an aw or an angled tool (I like using a paint can opener), pop it out.

willjayc · #4 03-15-2008, 09:10 PM

Tried everything to get it out (if it's there) I've had "glued" ones
before but I can't get it to pop and I've gone above and beyond my normal techniques. The coking on the removed injector tip is the same size ring as the hole in my new crush washers.

I seem to remember the hole in the prechamber being bigger than the hole in the middle of the washers but that was on my 79 240D.

I guess they are still in there??? Just reuse the damn things? The one odd thing though is that a thread or two show on the injectors once installed and torqued on the 240D I have, but even just finger tight the injectors show no threads on the 300D with the presumable stuck crush washers...this is why I thought maybe they weren't there (and becasue I can't seem to get them out or even tell that they are there to get out.)

Will

Stevo · #5 03-15-2008, 10:04 PM

Could the injectors be torqued down without the heat shields? Nah?... I know they get carboned down but a 90 degree pick usually does it.

Diesel911 · #6 03-16-2008, 12:09 AM

Quote:

Originally Posted by willjayc

Tried everything to get it out (if it's there) I've had "glued" ones
before but I can't get it to pop and I've gone above and beyond my normal techniques. The coking on the removed injector tip is the same size ring as the hole in my new crush washers.

I seem to remember the hole in the prechamber being bigger than the hole in the middle of the washers but that was on my 79 240D.

I guess they are still in there??? Just reuse the damn things? The one odd thing though is that a thread or two show on the injectors once installed and torqued on the 240D I have, but even just finger tight the injectors show no threads on the 300D with the presumable stuck crush washers...this is why I thought maybe they weren't there (and becasue I can't seem to get them out or even tell that they are there to get out.)

Will

Spray them down good with PB blaster or what ever your favorite is and let them soak over night.
If you have a slide hammer or some auto parts stores will loan you one for free get one that has a "Seal Hook" small enough to fit through the hole on the heat shield. Hook it in (being careful not to hit the hood with the slide hammer) and see if you can jerk them out.
There is also 2 body styles of injectors; one has a shorter nut than the others this may explain why more threads show on some than others. I guess it is also possible a PO installed 2 heat shields
If the above idea dose not work it might be possible to put some heavy grease (to hold the metal chips) on a tap and thread the heat shield and install a bolt and slide hammer them out.
Lastly machine shops have special expanding pullers used to pull out sleeve bearings that will go into the hole and expand and can be yanked or pulled out.

joethemechanic · #7 03-16-2008, 06:02 PM

Shove a rat tail file in the hole in the washer give it a little twist and they pull right out.

Rick H · #8 03-15-2008, 10:32 PM

I have jammed a wide screw driver into the hole and popped it out that way usually works pretty good. Rick

vstech · #9 03-17-2008, 01:21 PM

if there is a ring that is raised down there, the washer is still there.
if it is a concave depression then the washer is gone.

winmutt · #10 03-19-2008, 10:48 PM

No worries the prechamber cup would have caught it.

Easiest way to remove heatshields? Crank the engine over. Just don't stand in the way.

-Rolf

bgkast · #11 03-19-2008, 11:46 PM

and make sure your hood is at a 90* angle.

pawoSD · #12 10-04-2008, 11:08 PM

We have a stuck crush washer still in our new motor, in cylinder 4....we tried cranking over...didn't work, pried, clawed....can't get it out.

All the others came out easily of course....

The hole in the crush washer is slightly bigger than the hole in the pre-chamber....which doesn't help either.....

Any other tips? We soaked it in penetrant too.....

#13 10-04-2008, 11:58 PM

Find a flatblade screwdriver slightly smaller than the hole opening and pry on it.

pawoSD · #14 10-05-2008, 01:06 AM

Quote:

Originally Posted by ForcedInduction

Find a flatblade screwdriver slightly smaller than the hole opening and pry on it.

Tried this and it doesn't appear to work....

Question: How does one get said hook under the washer in the first place, if the hole in the washer is larger than the hole in the prechamber, so its recessed above that hole. So the hook will grab at the prechamber, not at the crush washer. I guess I'll just have to keep trying at it....

Diesel911 · #15 10-05-2008, 02:19 AM

Quote:

Originally Posted by pawoSD

Tried this and it doesn't appear to work....

Question: How does one get said hook under the washer in the first place, if the hole in the washer is larger than the hole in the prechamber, so its recessed above that hole. So the hook will grab at the prechamber, not at the crush washer. I guess I'll just have to keep trying at it....

Some of the Crush Washers come with a larger central hole or the hole has enlarged due to burning.
On the ones with a smaller central hole the Slide Hammer and Hooked Seal Remover can work.
Maybe you can stop up the Precombustion chamber hole with something rubber and fill the cavity with Penetrating Oil and let it soak for a day or so. Sop up the liquid with a rag and remove the plug; followed by some heat with a Propane torch.
After which use a Brass Punch and a light Hammer to tap on it and see if you can jar it loose.
The opposite way would be to soak it in Penetrating Oil and use that spray Freeze stuff to shrink it in hopes it will loosen. However, I do not think it is a good idea to hammer on it when frozen.