1971 220 - Page 32 - PeachParts Mercedes-Benz Forum

meltedpanda · #**466** 01-17-2007, 11:03 AM

surgery on the shut off valve was successful

still on the quest for the relay

daidnik · #**467** 01-19-2007, 12:50 AM

I have a '73 220 and have overhauled the 175CD carb before.

There is some info in the MBZ 114/115 Service Manual starting 1968, but I have more than that, but can't locate it right now. There was a great article on the carb in the "Star" magazine that I have a copy of when I can find my collection on this.

But, to the point. . . The starting mechanism of the 175CD is what the Star article called "The Heart of Darkenss" alluding to the pervasive misunderstanding on this. Underneath the water heating cover on the side is the cold start mechanism. It is a very small lever & pin mechanism, and I seem to recall that there is a part in there with very small orofices in it that must be clear. These must be clear and the pin/lever mechanism must be lubricated for the cold start enrichment circuit to work properly, which is one pump on the accelerator when the engine is COLD engages the cold start enrichment. THEN start the motor. A properly working Stromberg will start almost instantly.

Now, the shutoff solenoid is just a solenoid valve that pushes the needle seat up to shutoff the fuel flow. What often goes wrong with this is that the wires become broken or shorted because of the heat of the exhaust. It's best to take the carb out of the car to do surgery on those wires. Re-soldering and putting on some heat shrink tubing. You can also check the function of the solenoid by applying 12 V DC and seeing if it clicks. If you have the carb out, it is also easy to rebuild the cold start mechanism & put in a new rubber diapragm on the air piston. You might want to throw in a new needle as these get worn since they are designed to rub on one side of the seat. What looks like a little wear can result in a huge change in mixture. I had one go from not passing HC emissions to less than 1/5th the allowable limit with just changing the needle; no other changes at all.

meltedpanda · #**468** 01-19-2007, 08:51 AM

daidnik
Thanks, I actually have the article you mention being sent to me by another kind member here.
Your info helps, I am going to work on the cold start mechanism next as the shut off selinoid is working now, if you notice in my posts I am missing the shut off relay for this gizmo and still have been unsuccessful in obtaining one. I may try fabricating something if I can't find one.
I have read and been told that this 175CD is a very nice carb, when adjusted properly, your post seems to support that.
I notice you are new to posting, so welcome, stop by and give advice any time

meltedpanda · #**469** 01-19-2007, 03:37 PM

what are the pro's to taking this carb off the engine to work on the finer details versus leaving it on.
There seems to be enough room to navigate, suggestions from those who have been there, done that?

Mark DiSilvestro · #**470** 01-19-2007, 05:54 PM

Most everything on the Stromberg, except the float bowl, should be fairly easy to reach and service with the carb installed.

Incidentally, both Ford and Toyota have used variable-venturi carbs of their own design. Between 1978 and 1980 Ford used them on their full-sized V8 cars, and into the mid '80s on their police-package equipped cars. Toyota used one on their 1989 Tercel. Like the Stromberg, Ford and Toyota used a rubber diaphragm to operate the venturi piston and metering needle. Unfortunately, unlike the Stromberg, their diaphragms weren't easy to check or replace. In fact the Ford VV carb required a bunch of special, hard to find tools to setup & adjust it. There was even a conventional 2V Holley replacement availible for The Ford VV carb, much like the Quadrajet and Holley carbs marketed to replace the 4V Solex on Mercedes M110 2.8 engines.

Happy Motoring, Mark

meltedpanda · #**471** 01-19-2007, 06:14 PM

Thanks Mark, I have found that the Volvos of this vintage used a stromberg, but none are quite like the one on this ol gal.

I noticed that there is a three screw plate where the gas lines enter and exit, is there a filter or screen in there? If there is I probably need to clean. My main quest this weekend is the choke assembly, I think it can be worked on with it on the car. Wish

me luck....

Mark DiSilvestro · #**472** 01-19-2007, 06:40 PM

I don't believe there's a screen in the Stromberg carb. Usually those Mercedes used a screen in the tank and another under the fuel-pump cover. I like to install a proper in-line fuel filter between the tank fuel-line under the battery, and the pump.

Between 1971 and 1973, Volvos used twin Strombergs on most of their US-market cars. Unfortunately, if you're looking for a possible parts-source, I don't believe those had fuel cut-off solenoids. Starting about 1974, all US-market Volvos were fuel-injected.

Happy Motoring, Mark

meltedpanda · #**473** 01-20-2007, 10:00 PM

Well spent a great deal of the time under the hood today cleaning the carb linkages, removing varnish off the various plungers and adjusting the play and gaps on all the lever arms. ( I do have a nice article on this stuff) Replaced the shut off selenoid, adjusted per my limited knowledge,removed the water dome and studied how the thing worked. I had help today so I had him turn the key while I worked the throttle and various plungers under the dome. Would'nt you know it, I got it to start in about three turn overs

I then leaned it out, reset dwell and timing to specs, and then out on the road. She ran great, good acceleration, held strong on hills, no trouble getting to 65mph. It appears I have all the vacuum lines on correctly now.
Shut her off and had a bit of dieseling. I then restarted her , and hooked up an auxillary power source to the shut off, had my buddy turn off the key and I powered up the shut off at the same time and guess what - no dieseling.

I need that relay, or need to make one. I still am at odds on the water choke
What I cannot figure out is why it has a two prong electrical connection on it if it is in fact non electric???

I guess the real test will be tomorrow to see if I have the dome adjusted so the spring puts pressure on the right lever arm. I have a good article coming that I hope sheds some light on this process.
Well as always more to follow...

meltedpanda · #**474** 01-21-2007, 08:27 PM

adjustments seem to be pretty good, started fine when cold

the quest for the shut off continues!

daidnik · #**475** 01-22-2007, 01:19 AM

You mentioned the electrical connection on the starting enrichment circuit and that jogged my memory. I went out and looked at my '73 220 and. sure enough it was there.

The starting enrichment mechanism has both an electrical heater and the coolant lines. I'm not sure why this is so. As I recall, the dome-shaped piece with the coolant lines is just a cavity. It's seated outside the electrical heater and sealed with a ring paper gasket.

Information on this automatic cold start enrichment mechanism is the hardest to find. I seem to recall that the designation of this configuration was "175 CDT".

This lack of configuration on the subsystem called "The Heart of Darkness" in the Star article gives some indication on how there could be a lot of frustration and misunderstanding on this.

I'm still looking for my file on this thing. I did have info on this configuration WITH the automatic cold start, but I do not see it in the MBZ service manual for the 114/115 cars starting in 1968. I'm lucky that I had already rebuilt this carb before I let the car sit for the past 5 or 6 years with only very infrequent driving (several times per year).

Now I'm fixing all the things on the car to prepare it for my older daughter. I've owned several MBZ's over the past 23 years; a 111, a 108 and this 115. I really like this 115. I think it is the perfect car for a first time driver.

My 115 is in pretty good shape, and I'm putting about $1000 into it with new Bilsteins, new spring pads, sway-bar bushings, windshield & rear glass seals, door seal, vent window seal, with me doing ALL the work. I'm getting to around the last third of the work. I'll probably have to do the front & rear subframe mounts as well before I'll be completely satisfied, but the handling and ride is quite good just with the new shocks and spring pads.

meltedpanda · #**476** 01-22-2007, 09:09 AM

A kind kind lister found the relay in a boneyard carbureted 220 and its on its way to me. Talk about nice people, talk about helping out.

This is no doubt a great cyber group of MB enthusiasts.
daidnik, you are right this is a great machine for a first time driver, safe, roomy, and not fast

yes the electric part of this choke is confusing, I have the star article coming to me today so perhaps I will be able to gain some insight.
Yesterday when I started it cold I noticed that the pull off in the dome worked as designed, and once warm ran great. I am still getting a "miss" and I pretty sure it is related to my #4 cylinder, as I am using a "fouling plug" there to avoid the inevitable fouling of the plug due to a bad valve seal, at least that is my theory. (what else causes misses

)
The plan is to dig into that issue when the weather warms.

I have lots of pieces parts for the W114/5 so if you need anything I can take a look to see what I have
Thanks for your input and more to follow...

Cephallus · #**477** 01-22-2007, 11:15 AM

What helps is that these cars are starting to really develop some serious "cool" cachet. I get thumbs-ups from teenagers/20-somethings all the time in the w114.

meltedpanda · #**478** 01-22-2007, 07:59 PM

I got the article from the STAR. I am now convinced this carb is some kind of hybrid. I know the water choke feature is original but I am not sure the dome on mine is the original

In any respect I am beginning to learn the function and I think I have most of it figured out between the multiple articles I have and from the information from all of you fine folks. It looks like I have two more things to fool with, the pull off selenoid on the low speed lever (cam) and the warm up valve mechanism. The first needs to be set to some specs the second needs to be cleaned, I am up for the first task , a little leary of the second. "The Heart of Darkness" portion of this article goes over the water choke, but only briefly mentions the electrical connection, then again it mentions that there MULTIPLE versions of this carb

Probably can only study these things on paper this week as work will keep me out of the shop. Such is life.

Mark DiSilvestro · #**479** 01-22-2007, 11:08 PM

In addition to the water heating, my neighbor's '72 220 also has the aux. electric heater on his Stromberg's cold-start unit. I suspect it's to hasten operation of the cold-start valve for reduced emissions, or during extreme cold temperatures. My friend's is still hooked up. Perhaps the PO of your car decided it was yet another item that was NR!

Happy Motoring, Mark

meltedpanda · #**480** 01-23-2007, 08:52 AM

perhaps, I am thinking the PO or previous mechanic took a lot of short cuts, whatever was not woking they just eliminated

The reason I think that this is a different dome is that the article from the star mentions that the place to start with the adjustments is to line up the smalll mark on the dome with the RICH mark on the carb body, ( i have read this in other places as well) If i did this on mine ,the inlet and outlet for the radiator fluid would be at right angles and bumping into the gas inlet, in fact I doubt I could even do it with the current set up, it would also put so much tension on the spring that I doubt it could unwind enough to let off the cold start valve. In looking at the inside of the dome there is the ability to remove the spring, I guess another possibility is that this was done some time in the past and not put back in proper position
I also found a note in one of the many tune up books

I have that if the engine has "emisions controls" which I now have, to set the idle at 950 RPM. This makes sense to me as I have had a difficult time getting her to run smooth at idle at 800-850.
Later