I just recently had my 1976 230 go in to my shop to replace the head gasket (which subsequently didn't need replacing upon further inspection)
When I got the car back, saying the problem wasin the carb, he messed with my extremely annoying Stromberg Carb, making it unable to drive above 30 mph plus it backfires.

I proceeded to take it to a guy that knows Mercedes (he was trained on them in Hong Kong around 1975)

He has adjusted the air fuel mixture, changed the plugs, repaired the choke, checked the timing, and now we're in the process of replacing the ignition relay as part of the training manual he has in his shop.

All I know is that other than a sputter at idle and some initial smoke, the car was driving o.k. before, now I can't get it going at all.

Any ideas ?


Please help, I love my MB but I'm at my wits' end with this car !!!

AARON ROCHARD 1976 230

I would check two things first. First would be the large diaphram below the top cover. It is the device that lifts the piston as load is applied.

Second I would check the available voltage/ignition waveforms. Lack of available secondary voltage or a shorted coil wire/rotor can put the thing out like a light. As I have stated before all these things as testable. All you need is someone who knows how it works and the tools necessary (which might include an exhaust gas analyzer in this case).

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

Aaron,

I know you checked the timing, but did you also check the plug wire orientation?

I had the same thing happen after a top end re-build on a Misubishi engine. Turned out that in my haste to put things back together, I had the plug wires off by one, thus sending the spark 90 degrees out of sync. (Ah, the education we recieve) 30 mph, down-hill, in a hurricane with a tailwind was the best I could get, and the backfiring was horrible. Fixed the wire placement and I was back to crusin' 90 on the expressway!

This may not be close, but if the mechanic had the head off and did not pay attention to the wire placement......just a thought....

Good Luck

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William
76 240D (W115) - 550K miles
78 300D (W123) - 200K+ miles

Thanks, guys.

Steve, I'm not sure if my usual mechanic had removed the top of the carb while adjusting it so I'll ask him in the morning. I had it rebuilt recently, but if he was messing around in there at all, i'll have this new guy check it.

As for the wires, I've checked them and they're in correct firing order (1-3-4-2) according to my shop manual.

I've just ordered the ignition relay
(001-542-28-19) from my dealer and it'll take about a week to come from Germany. Hopefully I can get back on the road by then.

AARON ROCHARD
1976 230

Curses! My car is still in the shop! It's been almost a month now since the original gasket job. The Mercedes mechanic says that in order to follow procedure to fix the car, he must repalce the ignition relay (001-542-25-19) it costs $245 and comes from Germany special order! He says that he's checked the carb and the mixture is fine, the diaphragm is fine, it's just the timing that needs fixing and he can't do that properly until he relaced this part.

Does this make sense?

I'm worried that I'm spending good money after bad!

Subsequently, I've set up an appointment at the dealership is two weeks, should this problem continue.

Also, the transmission has started to leak, so, I'll have to get him to check it before he starts the engine (it was almost empty of ATF when I last checked it in his garage)

Ohhhh ! @#%^&*(*& !!!!
I just want my car back !!!

AARON ROCHARD

1976 230

Without looking at the exact circuit I can't say how the relay problem influences your car. These relays were mainly for emissions control and weren't present on early models 220/8 and 230.

If I remember correctly your problem was extreme. I hate to second guess your tech but whatever the relay is doing wrong could be by-passed for diagnostic purposes in my opinion. This allows you to move to the real problem without delay or expense.

I worked in the dealership when your car was built and have worked continously on MBs ever since and have never replaced one of those relays. Probably because their effect on running right or wrong is usually insignificant.

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

Thanks again, I have found a place that will repair my relay(oratleast test it to see if it needs repair) so the expense won't be all there as before, however, if this guy still can't find the problem, I'll have to go to the dealership, because I'm fed up with all of this independednt mechanics who say they know what their doing but continuously make my car worse. Hopefully it is something simple and I won't have to mortgage the house to fix my bloody car!!!

AARON ROCHARD

230 1976

Ahhh, finally got my car back. O.K. this is the update:

The guy who trained in Hong Kong also didn't know what he was doing, because I had an electrician test the circuits on the relay and it was fine. I got the car back form him still backfiring.

I then took it to another guy who fixes European carbs specifically, (he did his training in England on these Stromberg carbs) and now (after a day of adjusting) my car runs like a dream !!! It hasn't ever ran this good in the year that I've owned it.

Just FYI for anyone who owns an old 230 with one of these Stromberg carbs on it:


You can't trust 98% of mechanics when it comes to this carb. It isn't just that easy to set the mixture. Either you know it or don't, you can't fiddle with it until it works, they only make it worse.

Don't make the mistake I did, ask them specifically about the carb, read up on it, and preferably take it to someone who has worked on Triumphs or MG's, these British cars all carry Strombergs. A lot of mechanics (including Mercedes ones) claim that they know about this model ('74-76 230 )but really don't.

If you live in the Toronto area and need someone to adjust your 230, drop me a line at arochard@hotmail.com and I'll give you this guy's address and number. He's good.

Thanks again for all your input.

AARON ROCHARD

1976 230.4