Random bushing appeared in my footwell, and 280C/M110 idle control issue.

[ssk831]

So today I get into my car and see this bushing lying on the carpet. Anyone know where it goes? I think it goes to the windshield washer foot pump.




My M110 engine has been running perfectly for the past year since I got the car and did a solid service on it. 5000 miles later I'm having some idle issues. The car turns on from a cold start instantly, idles fine on high idle with oil pressure pegged at the top. It comes up to normal temps and still runs fine, oil pressure at 3/4 of gauge range.
About 30 minutes into around town driving my idle drops, oil pressure gauge dead center. Car sounds like it's having a slight misfire, like a small machine gun instead of the normal whooshing sound from the exhaust. If I don't give it the occasional touch of gas when stopped (I always put it in neutral) it'll stall.
I have a Sanden AC conversion, which has little effect on idle speed on cold starts or "normal". When I turn the AC on after the idle has dropped to halfway down the oil pressure gauge, the car will stall out unless I hold the gas at stops. To my understanding there is a bolt that extends via vacuum to hold the idle up when AC is turned on. The strength of vacuum goes down, letting the spring decompress and push out that bolt to raise idle under load. This bolt is no longer extending out to raise idle. A Vacuum leak would mean it is always being pushed out, so I don't think that is the issue.
tl:dr hotter the car gets the lower my idle goes, vacuum idle compensator is not working as designed.


Any help is appreciated.

[cefalu]

I thought the idle speed was increased when the AC was turned on by an electric solenoid, not vacuum.

Would you mind posting some pics of your Sanden conversion?

[kraakevik]

You might consider raising the idle with the angled adjustment screw to keep the car from stalling while you sort out the diaphragm issue.

These engines with Solex 4A1's are very susceptible to loss of vacuum. Leaks often can be found in the little vacuum valves, the check valve in the power-brake circuit and in the vacuum pump itself if so equipped.

Another idle problem can sometimes be traced to the "carburetor heater" controlled by fuse no. 2. This circuit must be energized to keep the choke plate fully open once the engine has reached operating temperature


Tim Kraakevik
kraakevik@voyager.net

[ssk831]

After several loud bangs from releasing my parking brake, I realized the bushing was the rubber stop for the pedal.

Tim, I have the idle screw set high for now. Only setback with that is a harder kick when shifting into drive or reverse. Also a uncomfortably quick creep speed. I'll look into those suggestions.

Cefalu here are some pics.

[cefalu]

Thanks for posting those pics. Your pics don't show it, but I guess your water pump mounted fan blade did not hit the sanden clutch.

I am having an interference problem between the compressor clutch and the fan blade.

Regarding the carb, there are those that won't leave the Solex. I couldn't make either of the two I owned work. So I bought a Holley economaster NOS on eBay for <$200. Its practically a bolt on replacement and it gets me 23mpg around town. Runs like fuel injected now.

[ssk831]

No, it doesn't. Any specific angle you'd like a picture from?

I really hate the Solex. It never runs right for more than a few hundred before needing some fine tuning. And while the car ran perfectly on my recent road trip, 15mpg was lame. Have my eyes peeled for a low mileage FI M110 and manual that I can just swap in. How is the power with your Economaster?

[cefalu]

Here is the recent thread I started while I was trying to figure out the clutch/fan interference issue. If you could take some pics of the clearance between the fan blade and compressor clutch that would be great. That's the issue I am still trying to figure out. I have an aluminum fan.

http://www.peachparts.com/shopforum/vintage-mercedes/339663-sanden-ac-compressor-280c-m110-powered.html

Regarding the Holley economaster, it's a 4 barrel like the solex. It has plenty of power, more than the Solex, but the Solex never ran right for me. The M110 actually works really well with it.

Here is the thread about it:

http://www.peachparts.com/shopforum/vintage-mercedes/315919-hah-adios-solex-4a1.html

[Mike D]

I don't know if you are interested or not but you can eliminate your auxiliary vacuum booster pump. It's not really needed.

Run a vacuum line from the intake manifold to the booster, remove the pump and plate the opening. The pump was dropped by MB in the later '74 models.

One less thing to go bad and cause problems.

[ssk831]

Cefalu, I'll get those photos for you. Also, Is your car Deep Blue? If so, that would make it the only other Deep Blue car I know of. Interesting they're both 280C's.

Mike, I didn't realize that was an option. Without the auxiliary pump, would the idle booster still operate on vacuum from the intake manifold?

[cefalu]

Its deep blue

Pics here in this thread

http://www.peachparts.com/shopforum/vintage-mercedes/340676-w114-lowering-springs.html

[ssk831]

Cefalu here are the photos you asked for, I think I got some useful angles.






And here's the rubber part I need. Seems to be no longer available. Will attempt to repair my broken one until I find a decent replacement.

[cefalu]

Thanks, just what I needed. They notched your fan to clear the clutch.