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1970 280 sel, 1979 300sd, 1988 300sel
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Discussion Starter #1 (Edited)
Own a 1970 280 SEL and drove it to a reputable MB shop (whatever that means) to check out why my car has been running rich. I previously posted information on my car not having the original M130 engine or head. I currently have an M129 engine and head. I have the correct distributor(cap and rotor) that goes with my engine. I had previously checked the cold start valve and that seemed ok. The MB tech called me today and asked if anyone had played around with the screw at the back of the injection pump and I said "No way". I told him that my engine was rebuilt about 9 years ago and the shop owner had told me that they had only played around with the Air/Fuel mixture screw/knob.
The tech continued to tell me that someone had turned the screw all the way in and he was having trouble backing it out. Again, I repeated to him that as far as I knew, nobody had messed with it. I continued to tell him that I also knew that the screw can never be adjusted when the car is on. He said he had big hands and was a little blind (not kidding, could of been a sarcastic remark) and could not really see what else was going on behind the injection pump but it would be a great idea to remove it and see what was going on. He also said that he had worked at a shop that rebuilt the bosch pumps many years back and was familiar with what to do. He gave me 2 options:

1. Remove the injection pump and take it in to get it rebuilt or calibrated for 1,500 dollars with parts and labor, or

2. Remove it and see what was going on and then reinstall for 800 dollars.

I swore that I would never get ripped off again so now I'm posting this to get advice on what to do and what not to do. So far there is no charge for anything that they have done which is really only playing around with the cold start valve , WRD, throttle plate?, venturi air fuel mixture, distributor etc.

What easy test can be performed to check the injection pump. The mechanic did not mention anything being broken at the back of the injection pump but just said he could not back out the enrichment/leaning screw out.

I don't know much about injection, obviously, but it just seems like way too much money to just see if it works or to just remove and repair the injection pump. Where is Arthur Dalton?
 

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1965 220S, 1999 Volvo V70 (wagon), 2006 Ford Crown Vic Police Interceptor, 72 350SL 4 Speed
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1,830 Posts
If someone tried to adjust the injection pump while the engine was running the mixture is screwed up. The injection pump needs to be removed and sent to a competent shop and adjusted.

See the following site for the good information:

Pagoda SL Group - Index
 

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64' 220SEc, 72' 300SEL 6.3, lots of parts
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512 Posts
same problem before

My elderly father took his M130 into a shop for smog check and a person did the same thing.

Screwing it in, richened it to not pass. The "respected" Mercedes independent quoted the $1200. so he called me and that weekend I went and "de-clecked" that thumb screw and adjusted to pass smog, 15 yrs later motor / car is still fine.

If you are delicate, push screw in and turn CCLW with small channel locks.
IT is possible to remove the cover and screw while in car.
IT is possible to break the adjuster screw too.

Who would put a lesser motor 2.5L into that car?
 

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1970 280 sel, 1979 300sd, 1988 300sel
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303 Posts
Discussion Starter #4
Don't know who would replace an m130 with an m129. I wish I knew a little more about these engines. I hear that a lot of the emissions on both the m129's and m130's were removed once the cars arrived to California. I also hear that the spark plugs were already fouled when shipped from Germany to the harbor. Who knows. I thought these cars were "built like tanks" but I'm not sure what everyone means by that. I have zero problems with my w116 300sd for sure but I want to believe that my m129 is capable of good driving with the right person maintaining the car. Step 2 for me is to play around with the injection pump and get that thumb screw loosened. No doubt that the car is damn right beautiful but I want to hear it purr not moan and whine...
I did pick the car up yesterday and a No Charge Receipt was placed on the front winshield.
 

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1972 300SEL 4.5, 1971 Citroen DS21, 1995 Jaguar XJS
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71 Posts
good that you got it out of there. See if the adjuster is free, that's the first step. Search for 'linkage tour' and adjust all the linkages, follow the tune up procedure and it should be just fine. use carb spray to check for vacuum leaks etc. around the intake and exhaust manifolds, throttle body injectors etc. good luck!
 
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