M189 Injection Pump Thermostat Housing?

[scoot]

I have a 65 W112 300SE sedan.  It has the later 6 plunger injection pump.   The thermostat housing is rotten and I have heard that someone has remanufactured this part.  Can anyone give me any information on this?

thanks
Scott

[Naj ✝︎]

Could be the same as 230 SL or 280 SL depending on long or short thermostat.

Naj

[scoot]

Could be the same as 230 SL or 280 SL depending on long or short thermostat.

I have 4 108/113 injection pumps and this M189 injection pump has a longer housing than any of them.  I don't know if I can replace the housing and what is inside with one from a different pump...
thanks
Scott

[ja17]

The M189 housing is completely different and unique. You can have these aluminum welded if it is not too bad. Otherwise PM me, I should have a used one.

[scoot]

Here is a picture of my problem.  If someone can tell me how to test the part on the inside (the big brass thing) I would appreciate that also.

[scoot]

After doing a little more searching I think I have more problems.  First image attached is I think from JA17's library of what's inside the injection pump housing and below it.  This would suggest that my injection pump thermostat has the rod broken off.  Second picture is where the thermostat housing and thermostat mount.  Looks like I'm missing the air valve and plunger (?)

Help is much appreciated.

[ja17]

OK, I understand now, (the housing on the injection pump)!  It's easier to weld since it is steel. It looks like it may be the same housing that is used on all the early 2 piston injection pumps or the earliest version 230SL injection pump.

[wwheeler]

I agree with Joe. My two plunger pump on the W128 uses the same housing as the early 113 with a tall thermostat. The ports are in different spots, but everything else is the same. I had the ports removed and welded in the correct spots for the W128.

In fact the opening of the WRD looks very similar to my W128. Note: I also have the later short six plunger housing, so I know the difference. SLS has both housings new. Not cheap, but they are brand new and fit. I have bought both from them.

The attached picture shows the SLS early tall housing on the left. The far right is my original housing on the W128 220SE. The middle is the welded housing to match the W128 housing.

[scoot]

OK, this helps.  It appears that my vast collection of injection pumps (actually only 4) include one with the long thermostat.  All of mine have a shorter thermostat housing, which is about 6 cm long from top to bottom of base.  The longer one from my M189 is nearly 8 cm.   Checking SLS I get a part number for the thermostat itself - A0012036175.   Cross-referencing this in EPC  I see that this part goes to M189, M127, M100 engines.  Oh lucky me.   If only it were the one from an M130 or M129 I would have a chance of finding one.   Well at least there is a chance for an M127 engine being parted...

Also looking at the picture I'm not sure that my thermostat is damaged.  But I have no idea what I'm supposed to see when I look in the cavity covered by the thermostat housing.  See my picture in previous post -- what should be in there?

thanks 

[wwheeler]

Both the tall thermostat and tall housing are available: thermostat from Mercedes $1000 and the housing from SLS.

I would be interested in knowing how to test the tall thermostat. It is different from the shorter one and NOT in just height.

So the cavity looks about like a tall thermostat cavity should. The hex nut on the side rotates and is for disablaing the WRD. It has a eccentric cam on the inside that depresses the plunger to the completely off position. When the cam is up, the plunger is free to move up and down. The short thermostat does not have this feature I believe.

Let me know how to test the tall thermostat.

[scoot]

Both the tall thermostat and tall housing are available: thermostat from Mercedes $1000 and the housing from SLS.

Yeah, well I won't be going down that path.  My housing is reparable I think.

I would be interested in knowing how to test the tall thermostat. It is different from the shorter one and NOT in just height.

I would too.  What I can say is that if I put the thermostat in hot water heated in the microwave the shaft in the center extends between 1 and 2 mm.  

So the cavity looks about like a tall thermostat cavity should. The hex nut on the side rotates and is for disablaing the WRD. It has a eccentric cam on the inside that depresses the plunger to the completely off position. When the cam is up, the plunger is free to move up and down. The short thermostat does not have this feature I believe.

Are you saying that the cavity I posted in my previous post looks correct?  Is it not missing something?  Are you suggesting that the plunger is completely depressed and that it should be popping up or something?  There is probably a 1 cm gap between the bottom of the thermostat and the bottom of the cavity...

Scott

[wwheeler]

It looks like the position of the plunger is at its lowest shut off position. That is what my W128 2 plunger pump looks like when the hex nut is turned so that the cam pushes the plunger down. If you turn the nut 180*, it should allow the plunger to come up almost flush with the top. The small spring pin near the hex head is what holds the cammed gizmo but allows to spin. 

That is the way mine works anyway.

[wwheeler]

Oh BTW. One way to fix that housing is to find/buy/make pipe nipples with the hose flare on the end. Then cut off the old nipples and have a good welder attach the new nipples. I had one of the custom brake and fuel line companies make short 6" double ended nipples with the hose flare. That is what is on the picture I attached.