1975 230 Stromberg Choke Issue 115 - PeachParts Mercedes-Benz Forum

Benzisit · #1 03-26-2006, 11:14 PM

As you may have suspected. I'm having issues with the cold start/choke setup on my 75 230. I reviewed this site and gained some useful info but need some more. Please. Unfortunatley I have not worked on a Triumph in 15years. I am familiar with strombergs but not with the water choke. Was suprised to see this relic under the hood. Not foreign though. Anyhow, my symptoms are.: Remains on fast idle. Runs good until warm under load. Then stumbles and falls until I let off the gas but still runs rough and can't exceed 30 mph. I suspect fuel overload. Pulled plugs and black as night. Sprayed carb cleaner on rubber sleeve between carb and intake and did not change idle speed. Checked vacuum lines. Appeared fine but did not spray down. Suspect choke. Ok. Then I removed the choke housing. Sprayed carb clearner everywhere and ready to run at a moments notice. Attempted to move the arm that is visible through slot. The arm was located completely on passenger side in the slot. When I attempted to move arm it was very stiff & only moved the piston slightly. What is this piston with rubber sleeve? Can it be removed and cleaned? Should it depress totally? Should the arm move completely to the right? So... I Put everything back together and seemed fine for a while. Way lower idle. Ran good but after about 2 miles symptoms returned. I walked away frustrated. Currently the car is cold. Car off. I looked through slot. Arm is completely toward passenger side. When looking in slot I applied throttle and arm inside did not move. When I attempt to move arm with small screwdriver it only moves slightly. Please advise. Any help appreciated. Should I remove housing and clean again? I know I can fix this (it's a Benz) with your help. Thanks
Reid

meltedpanda · #2 03-27-2006, 10:37 AM

Ahh the famed stromberg. On my 71 I had similar problems.
A very knowledgeable lister sent me this and it really helped (thanks MarK)

First determine whch way the bi-metal coil rotates as it warms up. The slow, safe way is to let the coolant heat up the cover while it's loose of the housing and watch. The quick, less-safe way is to use a match or lighter under the coil for a few seconds. Watch the coil as it heats up and rotates towards the warmed-up position. When the coil cools off again and you reinstall it, it should gently press the linkage to the cold-start position.

Also, while the coil/cover is off, you can start the engine, look inside the housing and see if the pull-off pin pushes on the cold-start linkage perhaps 1/16 of an inch, moving it away from the absolute cold-start position. (The pull-off is needed to prevent flooding in the few minutes before a cold engine warms up enough for the coil to move the valve)

Make sure the fast-idle cam works and engages properly. (Sometimes there's a tiny adjustment screw on this cam that falls out or gets left off, but I don't recall if that's true on this Stromberg)

Make sure when you reinstall the cover that the coil connects to the linkage so that it can positively open AND close the cold-start valve. (You'd be suprised how many persons re-assemble one of these things and miss this little detail)

Also make sure you've cleaned and freed up the linkage so that it moves easily and you won't need to rotate the coil/cover to cause excess pressure and force it to the cold-start position. If you reinstall it with too much pressure, it won't be able to move the cold-start valve as the engine warms up.

With everything working smoothly and easily, the bi-metal coil has just enough strength to close and open the cold-start valve, according to coolant temperature, so you shoudn't need to over-compensate with the adjustment when you put it back together.

With the engine running, if the pull-off is pulling hard against the cold start linkage, it's probably working. If it WASN'T pulling, then it would cause a too-rich condition. Also, the cold-start itself could be set too rich.
The main jet adjustment is at the solenoid on the bottom of the carb and it should be performed when the engine is warmed up. There's a (19 mm I think) locknut to loosen and then you turn the whole jet/solenoid in to lean or out to richen. Keep in mind the main jet adjustment affects the whole range on these carbs, from idle to max power. Try to note how much you adjust the main jet, as a slight turn makes a big difference on the Stromberg.

I went through this several times. My black wet plugs now show a nice brown tan color and I have good pick up. These carbs are also prone to vacuum leaks so check closely. I did remove my cold start valve and cleaned out the junk. it may have helped and should be checked. Are you venting crankcase properly?