Throttle body housing

[MarkCan]

I’m in the process of rebuilding the throttle body on the M127.981.II engine. I have it all apart cleaned and almost ready to be assembled back together.
On the suction plate shaft (142 in the diagram) there are two seals/o-rings. One on each end inside the housing, (att.pic). For some reason I don’t see them on the diagram neither on the parts list.
Second is the pressed in seal on the outer part of the body (att.pic)

I would appreciate your input on that matter.

[dirkbalter]

Mark,
You can see and get them from SLS for example. See below.
https://www.sls-hh-shop.de/main/de/mercedes-230-280sl-w113/07-09-14-mech-einspritzung-saugrohr-/07-a-einspritzanlage

[Figoulu]

Mark,
You can see and get them from SLS for example. See below.
https://www.sls-hh-shop.de/main/de/mercedes-230-280sl-w113/07-09-14-mech-einspritzung-saugrohr-/07-a-einspritzanlage

Excatly, something I just ordered yesterday as well... 2 O Rings and another style additional ring
I believe it's important to avoid air absorption at that stage

[Pawel66]

I
On the suction plate shaft (142 in the diagram) there are two seals/o-rings. One on each end inside the housing, (att.pic). For some reason I don’t see them on the diagram neither on the parts list.
Second is the pressed in seal on the outer part of the body (att.pic)

I would appreciate your input on that matter.

Mark, I think it is all there on the piece of the picture I am showing below, where the spindle cover is shown (for models with no switch). Have faith in the EPC! It tricks you only sometimes .

[MarkCan]

Mark, I think it is all there on the piece of the picture I am showing below, where the spindle cover is shown (for models with no switch). Have faith in the EPC! It tricks you only sometimes .

Are you referring to part 138? I thought about it but it's position in the diagram confused the heck out of me. In reality the o-ring is the first piece on the inside of the throttle body shaft.
Thank you.

[Pawel66]

Yes, 138 is the one you need two pieces of (A 000 997 71 40). Then there is the other one you asked about, 141, 1 piece, PN N 006503 008200, replaced with A 000 997 46 46.

Indeed, location on the picture is somewhat misleading...

[MarkCan]

All on order and than some. I hope to have it before the end of the week. I need to push a little harder here as the Canadian winter is just around the corner. Even with the good heater in the garage temperature drops quite a bit. 🥶

[MarkCan]

I got some parts and it was time to continue.
https://youtu.be/toXnHAQtFXQ
Unlucky for me the o-rings were so hard that I couldn't remove them without risking some damage to the t body. I thought that good night slip will bring new ideas to the table and I was right. Today I made a tool out of an inexpensive pick and it worked like a charm. Got it all done. 2nd video is currently uploading. Should be ready in the morning.

[MarkCan]

All done new seals are in,
https://youtu.be/EisNRwnlbxE

[MarkCan]

Tonight task number 1 - build that puzzle!
I got almost all the parts for the distributor and I’m picking up last few tomorrow.😀
Throttle body is there as well. I hope to finish it tonight.
Looks like the spacer/shim needs to be .8mm in my example. I made one up from stainless washer but still need to grind it down another.2mm for proper fit. Throttle plate travel adjustment pins are temporarily substituted with Allan head bolts and will be replaced with stainless soon.
Throttle position potentiometer looks to be salvageable - nothing is physically broken 🤔

[MarkCan]

Just testing,

[Shvegel]

Wickedly expensive switch for what it does.

[wwheeler]

I had some issues with that switch operating erratically over time. I would clean the points and would work fine for a bit then become unreliable once again. Turned out to be the crimp for the points on the main body. I guess it was coming loose causing the intermittent problem. Very frustrating but haven't had any issues since I re-crimped it.

Yes stupidly expensive and surely an easier and less costly way to do the same thing. MB used to offer a "rebuilt" switch that to me looked brand new. I got that one a few years ago and now the price has jumped through the roof. Now it is NLA like many others.

[Pawel66]

I am closer and closer to the idea of having it done through a relay...

[wwheeler]

I had it going through a relay and it didn't really help the longevity. The mechanical crimps in the switch were the culprit in my case.  The points in this switch are quite substantial and possibly more so than the points in a typical relay. Make sure you have the switch adjusted correctly though.
I guess though if you would rather burn up a set of points, it might as well be ones that are easily and cheaply replaced like a more modern style relay.

[Pawel66]

Thanks Wallace, my concern were the points indeed. I started looking to buy just the points to replace, but have not found a place to do it yet. Maybe the crimps can be fixed somehow in the garage...

[wwheeler]

I just used a chisel and peened the connection in a couple of spots.

[Pawel66]

Ok, so it just got loose and could be salvaged, thank you.

[ja17]

The same switch was used on the carburetors of many finback and W108 Mercedes of the era. Only the early models with the pagoda style automatic transmissions used the switch. The switch performed the same function, but were mounted on the throttle shaft of the front Zenith carburetor.

[Pawel66]

Thank you, great lead!

[MarkCan]

Guys,
It looks like I have a small air leak through the plate in the fully closed position.
Are there any kind of coatings for that purpose?  Plate itself looks to be in excellent condition. Is the body inside circumference that may not be perfect and most likely isn’t.
I’m open to suggestions.

[Benz Dr.]

Small air leaks can be balanced out by using the idle air screw.

[MarkCan]

Small air leaks can be balanced out by using the idle air screw.

Thank you Dan.
That’s what I’ve done so far. I thought, since I put a lot of effort in to this already, I may as well try and make it perfect.
I’m looking at places that could coat or bore the existing body and install a new butterfly.
Not to many around, at least here in Canada. I found a guy in US but he doesn’t take any business from abroad.
I’m open to suggestions.

[Kevkeller]

Maybe you can use some Prussian blue on either the butterfly plate edges or the inside of the housing and file off any high spots on the butterfly plate.

It probably won’t make a difference unless the leaking is very bad.

I haven’t looked at the butterfly itself but is it locked into one position when screwed in or can you adjust it?

[Benz Dr.]

None of those throttle plates fit all that well anymore but it's not critical to close them off perfectly. As long as you can obtain a smooth idle and the throttle plate bites a small amount when fully closed, that should be good enough. This is one of those places where perfect really doesn't matter.