Back to an old irritation. I lost a jet out of Zenith 175CD carb (Or was that a Solex) on this car and went all over the world looking for one including the old parts warehouse in Germany. They say they no longer have soooo back to square one with my dear 230 still idle.

Do I need to go with a webber?? and is it a bolt-on?? If so, who has one handy?? Or do I need to go to my flathead Ford pile & recondition an old Stromberg 97 for crying out loud? I just want this sweet little thing running.

Chuck?? Or,???

Sparky

The Zeniths (which i don't think you have) are 'down-draft' carbs with the venturri vertically disposed.

The Stromberg 175CDTS, which I DO think you have, is a 'side-draft' carb that has a horizontal venturri and an air piston that moves up & down to vary the venturri cross-section. There is a plastic oil reservoir on top of the air piston cap that is clearly visible on this carb.

It does not have a "jet", but has a needle connected to the air piston and a needle seat that is fixed in the carb body.

There is no jet to "lose" in there.

The needle needs to be replaced about every decade because of abrasion wear against the needle seat. The needle is most certainly available and costs about $32.

Yep, it surely is the Stromberg 175CD. The "jet" I speak of is threaded up through the bottom of the fuel bowl and the needle drops down into it. It is what you call the needle "seat". When you hit the throttle, the piston raises and draws the needle up out of the seat and enriches the fuel mixture for acceleration. There is a tuning procedure that is described by John Twist at University Motors that requires screwing the brass seat in or out to get a smooth transition between idle and acceleration. My seat has an "o" ring in the middle to seal off the fuel bowl chamber and allow for adjustment. Maybe it is the equivalent of a "power jet". But it is the brass piece (seat) that threads up into the fuel bowl that fell out and I can't locate one anywhere. I have seen some that seemed to have a small tube coming out of it and a fitting on the other end that seemed to have somewhere to go. Mine didn't have that. ( Otherwise it would have not come off) It took awhile but I finally found the right part number with Phil's help----alas but no such part left in the MB old parts inventory. ( after they said they did have some and left me hanging for two months before they told me they didn't) I must have the part # around here somewhere but that 175 CD seemed to be specific to the 1978 model. Maybe one of those with the tube coming out of it would work but I don't know. I'd take anything that might fit & I could adapt something.

Ah, "But for a nail, the shoe was lost--------"

Embarrasing admission:
It dropped out on I-29 within the city limits of Sioux Falls, SD where I live. I don't dare walk the Interstate but I would if I thought I could get away with it. Oh I'd hate to be flat for the rest of my life.

Thanks for the response. Someday.

Sparky

Yes, the whole seat assy with the solenoid shutoff valve threads in thru the float bowl cover in the bottom.

It's almost impossible to lose this. I'm almost certain that even if you unthreaded the solenoid shutoff valve assy completely, the needle seat still wouldn't drop out the bottom (this would still not be recommended and is certainly not necessary).

To get to the needle seat you have to remove carb from the car and them remove the solenoid shutoff valve, then remove the float bowl cover to expose the needle seat assy. Now, this is also not usually needed. It is only really needed if you have fuel leakage out from the joint of the shutoff valve and the float bowl cover, and this will be a very slow leak, but is most notable by a gassy smell under the hood, and if the region above the cylindrical shutoff valve is clean, then pop the hood first thing in the morning before starting the car, and if it is wet there, then you've got a slow leak.

To fix that, you DO have to remove the carb; remove the shutoff valve; remove the float bowl cover to gain access to the needle seat assy and replace the o-ring that seals that whole assy to the float bowl. It IS likely that you will have a leak because of the age of the thing, but like I said, it will be a small leak.

Now, back to the matter of functional running and mixture. There is only ONE adjustment for this aside from the obvious idle speed screw. This adjustment for mixture is to raise/lower the needle seat assy relative to the air piston/needle assy. This is done by cracking loose the hex nut on the threads on the shaft of the shutoff valve assy at the bottom and screwing it in to raise it (lean it out) or unscrew it to lower it (enrich the fuel mixture). If you're uncertain about where you are, it's best to lean it out first until you start to get a little uneven running (lean misfires) then richen it gently just enough to get even running. You'll also want to pulse the throttle after each tweak to burn off any sooty-ness on the plugs.

Then drive the car and repeat as needed. Even with a very worn needle profile, you will still get quite good running provided that the rubber diaphragm that lifts the air piston doesn't have any leaks. This is a cheap part and is very easy to replace. It only requires taking off the dome at the top (4 screws). Likewise the needle can be replaced at the same time, and this IS the part that wears out, not the seat. You won't notice a a lot in the drivability, but it will will hurt gas mileage, so if it's a decade or so old, just get it along with the diaphragm and do it right.

Several notes of caution about this procedure on the Stromberg:

Be very gentle with the single wire coming straight out the bottom of the solenoid shutoff valve; it's easy to break this with decades old insulation. There is a single push-pin connector about 8-10 inches down the line. Disconnect it and gently coil up the wire to hang under the shutoff valve when you turn it around to adjust it. Re-connect it after you're done and tuck it under that air intake assy.

Also, be gentle with the locknut on the shutoff valve (19 mm across the flats). All this nut does is keep the valve from unthreading; it is NOT the mechanism of sealing against fuel leakage, that is the o-ring that's inside. If you've got leakage, you'll have to replace the o-ring. All the required parts are available and I did all of this in the past couple of months; needle, diaphragm, float bowl gasket and o-ring; the parts ARE available.

Is it the same Stromberg 175CD that was used on MGB's?

http://www.victoriabritish.com/icatalog/mg/full.aspx?Page=129

It's pretty close, but I doubt that the parts would interchange. The basic concept is the same but there's a lot of extra stuff hanging off it. And it's German....

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

If so, then that would be a W123 chassis which is exceedingly rare to see with the 4-cyl motor. I know this because I have a '73 220 with a transplanted '74 230 motor in it that has been there for the past 20 yrs since I got the car. Its a 115.951 motor that was in production for 3 years only, 1974-76 and went into the last of the W115 chassis with the gas engine.

The W123 had 2 years only with this motor design; 115.954. I don't even know what difference(s) there is from the 115.951, but they have got the be very small as they use the same piston.

Last summer I completely overhauled the 230 motor and I had very tough time locating a piston set in ANY oversize. There are lots of diesels out there, and a lesser number of 220's, but when you get to the 230 motor, they are really a rare item, especially in the W123 chassis. Europe and the rest of the world bought lots of 4-cyl diesels, but the US market wasn't interested in 'underpowered' 4-cyls, so the Mercedes 4-cyl gas motor was orphaned into extinction.

I eventually found a 1st oversize Mahle piston set in Australia; $1300 with shipping, but I got them.

"... dropped out on the I-29 ..."

If this is so, then there will be a hole in the bottom of the rectangular float chamber cover on the bottom. Also, if you crank the motor over with the starter, gas will flow out of this hole. Is this the way things are?

If so, you will have to remover the carb so you can remove the float chamber cover and see that the needle seat and there's a spring and a washer I think. These may be laying in the float chamber rattling around, don't lose these parts.

I looked up in EPC on a late chassis W115 with the 115.951 motor and the solenoid valve doesn't say NLA. P/N: 000 072 0117; super-deal pricing @ ~$234. This P/N should be cross-ref'd to your chassis VIN just to make sure it's the same. Then check stock for P/N in Germany. Even if you had to buy this along with the gasket, o-ring, needle, diaphragm, it's still going to be lots less than a Weber conversion IF you could even find that kit which I doubt, it would be quite expensive and a lot more work.

1978, VIN-12302312099641, Sorry, no wire leading out of the seat. I've had it in and out many times. No moving parts, no springs, no wire or place to connect it. I know that the local MB dealer wanted to sell me the one with a wire. We finally found the PN and description for the correct one that went with the correct PN carb for the correct SN motor. that is when I got the promise (about $8.00or so) and later, the disappointment. They once sent me a piece that was obviously meant to be the fitting that a seat screwed into for the shut off thing---wrong.

Nope, mine is just a seat that screws directly into the fuel bowl bottom where there is a bored hole where the o-ring fits and seals. The needle drops down directly into this part.

My carb has been off for a long time. If I could wiggle my way around the whatsis to post a photo, it would be clear but if you send a email to gssparhawk@sio.midco.net , I'd be glad to forward some. I have sent some to various persons for ID before and it seems that the configuration I describe may be specific to this single year.

I have also followed the John Twist adjustment procedure which is just like what you describe---and it worked just fine.

Sparky

Also, this one is NOT like any others used in Britt cars or any others that I know of. Maybe a 1978 Yugo???? ( Experimental at that time, I think.)

Sparky

There may be detail differences between the carbs, but the 175CD was used on a number of cars other than Benz. Volvo, MG and Triumph come quickly to mind. The part you are missing is very likely the same on all these carbs. A quick google search should lead you to a place that can sell you the part, or a complete used carb if it comes to that.

There's always this...

M115 T.B.I. conversion