Heat Shield or Housing Assembly?
 

Greetings,

As I prepare to received my rebuilt W115 240D ('76) injectors from Greazzer, I assumed that the pictured were my heat shields that were stuck in the injector housing. My mechanic and I used a dash pull but didn't get any movement despite some serious pulling and tugging.

Are we dealing with stuck heat shields? If so, how on earth do we get them out.

If not, are we mistaken and is it a part of the housing for the injector? If so, we didn't see any heat shields when we took the injectors out.

Anyone experience this on a W115 before?

I have never seen them but in some of the threads people mentioned that in the past before there was what we now call heat shields there was those plates that that seem to be pictured in you photo.
In one post it was mentioned that the plates were supposed to be reusable but I don't know if that is so.


penetrating oil (marvel mystery oil seems to eat on carbon if you had any of that that you could drip around the outer edge it might help), heat with a propane torch and using a 1/4" diameter brass punch and hammer to beat around on it from side to side stands a good chance of breaking it lose.

Not in the diagram #53 is the heat shield. With the 10mm hole there is nothing for a dash hook to catch on as the pre-chamber hole is what looks like the same size. The heat shields that cam with my car had a 5mm hole which allowed an area to hook onto to pull them out.

For several years after 2007 they sold the 5mm heat shields and after that most companies went to the 10mm holed heat shields. You can still get the heat shields with the 5mm hole if you buy heat shields for a VW Rabbit Diesel from the 1980's. (Not the VWs and my Volvo Diesel use the same injector bodies with different nozzles in them.)

More radical ways would be to pull the pre-chambes and put them in an ultrasonic cleaning tank.

The other one is way beyond any sill I have. In the old days to remove stuck pressed in valve seats they used to weld a bead on the inside diameter and when the weld cooled it would contract and shrink the valve seat.

If someone had the skill to do that around the central hole on the heat shield it would work. It may be even that just applying a weld anywhere on the heat shield surface would put enough heat into it to warp it and therefore free it.

Heat changes the dimensions of the heat shield and therefore that is kind of a movement. Once something moves it can often be freed.

I have not used freezing sprays enough to know if that would work. But, maybe penetrating oil soak followed by freezing it and followed up with the Brass Punch/drift Hammered on while it was still cold would free it. Freezing also changes the dimensions and is safer then welding.

Thanks for the info. I'm trying to determine if these are the reusable T-type heat shields or if these are the normal disposable type. If its the former, probably best to leave them alone in there?

First find out if seals are available,top hat type.
How I got them out was to use a twist type of easy-out,tap in ,turn and wiggle back
and forth,worked every time.

There's a much easier way to remove carbon stuck heat shields! Flat faced punch and hammer lightly tap around the heat shield to break the carbon bond. A wire hook should lift it out.

The reason heat shields gets stuck by carbon is they were not sealing/ seated properly. Clean all mating surfaces before installing new heat shield. A good way is wrap a wad of denim from jeans (tough cotton) around a flat blade screw driver with twist tie, dipped in penetrating fluid. Twist it back and forth in the pre chamber to pick up the gunk. Change denim as often as needed till no more gunk is on the denim/ pre chamber.

In this thread there is a picture in post number 3 of the disposable heat shields with 10mm holes and you can see how both sides are machined.
On the left of the picture is the side that fasces down towards the piston and on the right is the side that faces the Injector.

http://www.peachparts.com/shopforum/diesel-discussion/175380-fuel-injector-heat-sheild-om617-95-a.html

http://www.peachparts.com/shopforum/diesel-discussion/323265-removal-injector-heat-shields.html

I've seen that type of heat shield before and my opinion is that they were not meant to be removed. I recommend you leave them alone. See this post which shows the three types of pre-chambers I've seen in OM616 engines in W115 chassis:

http://www.peachparts.com/shopforum/3882687-post11.html

I have a set of the S&K chambers like yours that came to me in my 1974 240D. I've since swapped those pre-chambers out, but I ran them for a while before installing another set. They seemed to work just fine in terms of sealing the injector nozzle against the pre-chamber. I didn't see signs of compression leakage on the injectors I pulled from them the first time, nor on the other set of injectors I ran in them for a while.

Unlike hercules I did not have luck attempting to remove that steel disc from one of the pre-chambers I have. I ended up mangling the steel disc and it still didn't come out. Maybe I wasn't trying hard enough! Assuming you could get the discs out I bet you could then use the normal heat shields in those pre-chambers.

I don't see the normal groove. I will take a picture of one tonight and you can compare.

Many thanks guys. We've tried everything that will not damage the shield and still can't get it out. Imagine two guys spraying penetrant, armed with heat guns and dash pulls. Still nothing!

I see no signs of damage to the shield and could believe it is reusable. That said, my injectors had suffered damage. Greazzer was kind enough to confirm all of them "peed" pre & post pop, so maybe it was because of the poor spray pattern and not the lack of shielding?

I've seen the nozzle damage you described in another thread. Was it confined to the area of the nozzle that's exposed to combustion right around the needle, and not under the area sealed off by the heat shield? That's how I've seen it.

NOTE: I took a look at the pics you supplied here:

http://www.peachparts.com/shopforum/3969582-post1.html

The nozzle damage seems pretty well confined to the area that is exposed to combustion.

Correct. This is quite common in worn injectors. Greazzer did confirm that my nozzles were peeing, so I'm not sure if the wear is because of the heat shields themselves.

If they are peeing it does not matter what heat shields it has the exposed area that is not covered by the heat shield will get burned away. So I am not seeing the heat shields as the cause unless it is burned in the area covered by the heat shield. If that happened I would suspect the heat shields.