It takes like 4-5 tries and some pushes to the gas pedal before I can start my 75 280c in the mornings. Last month I took it to German Auto Center here in San Antonio TX, I took it twice to this place with no results at all, the technician made adjustments & cleaned the carburator, checked vaccum sistem, replaced a "plate" (the one between the carb & motor), and I still have the same problem.ANY SUGGESTIONS?
I've been reading about other car's with the same problem, and it seems to me that it wouldn't hurt to check/replace the Overvoltage Relay and the Fuel Pump relay. Could anybody tell me if this car has these two components and their location if applicable.

Thanks,
Panchillo Garcia
75 280C / 110k miles

No such nice neat fixes on that guy. Mechanical fuel pump and nothing electronic anywhere but the ignition module.

Probably a Carb/choke problem. It also could probably benefit from some additional timing.

I would strongly suggest that you give the shop another try at it. That carb gave us fits when the cars were in warrantee and it didn't get any easier when the customers started paying for it.

Since you already have given them some money the path to repair should be cheaper here. I would be prepared to leave it with them for a couple days so that they have plenty of oportunities to verify their fix. They might need to see the warm up cycle two or three times to be sure.

As it turns out I will be in San Antonio tomorrow for a Diagnostic Workshop being held at Rhine West (a BMW specialist). I will be at the La Quinta 333 NE Loop 410 tomorrow evening and would be glad to drive it for you and verify that warm operation is up to snuff. I don't know the room # yet but if you call for me I should be there. Steve Brotherton

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Geee, that wouldn't be a Solex 4A1 carburetor would it?
-Larry


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03/83 300D 184k
07/73 280 160k

How can I find out if it is a "Solex 4A1 carburetor"?.....
Thank you very Much Steve Brotherton, I'll give you a call tomorrow...

Any other suggestion?

Francisco Garcia

It will say Solex 4A1 on the drivers side of the carb body, towards the top of the unit, just under the aircleaner lip.
-Larry

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03/83 300D 184k
07/73 280 160k

Its a Solex 4A1 unless someone has changed it. That was the only carb MB ever put on the M110 engine.

I have seen Holley make-overs and even a few Rochester Quadrajets (almost identical carb except they were always jetted for a V8.) I always wanted to find one (quadrajet) that came on the single overhead cam Pontiacs inline six. It would have about the same displacement and would have done a lot better than the V8 quadrajets.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Francisco,
I would bet that you have a choke problem (not closing when engine is cold) or possibly a bad accelerator pump. You can verify the accelerator pump by removing the air filter housing and looking down the primary (small) barrels of the carb (engine off) while you operate the throttle linkage. If fuel squirts down the barrels when you operate the throttle, the pump is OK. Does the car run OK when warmed up?

Just FYI, it has been my experience that all downdraft Solex carbs are somewhat troublesome, and great benefits in performance and mileage are to be had from switching to Weber or (in your case) a small Holley four barrel carb. A few years ago, Holley was making a small (450cfm) bolt-on replacement for the Quadrajet carbs which came on many GM cars in the 60s and 70s. If your carb is beyond help, you may want to ask Steve B. about this, as I'm sure he'll know how to solve the problem. Good Luck!
Colin

It runs great ones it is warm, the only problem is when the car seats for 6+ hrs, before I try to start it I have to push the gas pedal a few times and cranck it at least twice.
The other problem that it had before I took it to the Shop, was that it use to hesitate for 1 second before going from 0 miles/hr +, but they got rid of that problem, I guess he adjust the carb giving it more gas while on idle.

Thanks for your help.
Francisco

Another possibility is that the float chamber in the carb is leaking fuel, either externally or internally down into the manifold, while the car is sitting. When you try to start the car after a period of sitting, the mechanical fuel pump has to refill the empty float chamber, while cranking, before any fuel gets to the cylinders.

To check this, let the car sit for a day or two without starting it. Before you start it, remove the air filter housing and have someone pump the throttle while you look down the carb. If little or no fuel squirts from the accelerator pump jets, the float bowl has emptied while the car sat. A carb rebuild with a new float, needle and seat, and gaskets should cure the problem, if this is it.

Actually the guy from German Auto Center said he was going to "rebuild" the carb, what ever it means. How can I identify the float in the carb? What do you mean with "needle and seat"?

Francisco

Any other ideas?

To find the float, along with the needle and seat that it attaches to, you have to take off the top of the carburetor.
Unless you have done this before, You should let someone who knows what they are doing, do this. He/She would have the necessary calibration tools and so forth to do the job without mistakes. (mistakes that can leave you stranded).
-Larry

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03/83 300D 184k
07/73 280 160k