My 1982 Mercedes W123: Checking carb, air filter, spark plugs & more

The spark plugs looked in excellent condition but since they are old, I am going to replace them.

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One of the things I learned during our brazing workshop a few weeks ago is that I need to upgrade my torch. One of my mates from the model building forum has helped me find a very nice second-hand set. Original Perkeo.

He is checking it for me and will add some components to it and will provide me with the necessary reducers and so on. I just ordered myself a 5L bottle of oxygen and a 1L bottle of propane. That should keep me brazing for a while. Hopefully, by the end of next week, everything will have arrived.

I took the Mercedes W123 back to my MOT guys. Passed with flying colours of course!

Another MOT (APK) is good for two years of motoring!

I have been giving some thought to what I want to do with the carburettor. Although it is fine now, the fact that the CO went up this much, is likely an indication it needs a proper overhaul. All the carburettor specialists have given up on overhauling this particular type of carburettor, due to a shortage of some critical parts. I checked and as luck would have it, I still have these parts in stock!

I thought the first thing to check is whether I could find any air leaks.So after it passed the MOT it was straight back into my garage.

I hooked up one of my analysers to keep an eye on the RPMs.

With the engine idling away, I then proceeded to spray starter fluid all over the various parts of the carburettor and the various vacuum hoses. The idea being, as soon as there is a leak, the starter spray gets sucked in and the RPMs will raise.

Could not find anything. So I will try and fix the slight engine stutter first. Then re-adjust / check the CO one more time followed by driving a few thousand kilometres and check the CO again. If it has deviated again, I will start work on the carburettor.

Took the air filter off, not in too bad condition, but I am replacing it nevertheless.

I took the four spark plugs out. They all looked in excellent condition. Nice grey appearance, exactly as it should be. But they are old, so I am going to replace them.

Next, I checked the spark plug leads and cleaned them. Took the distributor cap apart as well. I have seen a lot worse! Still, I ordered a new one.

Checked the rotor too, again not bad, but I just ordered a new one as well.

Cleaned all the various parts with my Dremel.

The air inlet filter has a valve which allows air to drawn from the front of the engine compartment, or during cold weather draw inlet air across the exhaust manifold. It is operated by a simple mechanical thermostat. I replaced it quite some time ago. Have a look here.

Initially, it sort of looked ok, but I decided to test it by taking it inside and then bringing it back out (it is 4oC here). And it got stuck in the interposition. So I ordered a new one.

Next, I checked the oil separator on the inside of the air inlet housing. Not very dirty at all.

Cleaned it and put it back together again.

The oil will drain back into the valve cover, any oil vapour is drawn into the inlet manifold. I noticed that the connection from this small hose to the tube on the inlet manifold was not very secure. Might have had some false air in there. Did not check it with the starter fluid, as it is more or less hidden under the air inlet filter when everything is installed.

Checked and cleaned all connectors on the electronic ignition. (Yes this is a forty-year-old carburettor car but with electronic ignition).

I also verified the proper working of the vacuum advance. Well, what I did is such on the vacuum line and you can see it turn!

Finally, I swapped the yellow registration plates for the (illegal) blue ones. Yes, they are illegal, but I have never been fined for them. And even the cops will admit to the fact that blue plates look so much better on this car!

All the parts will start to arrive over the next few days, so hopefully, I will have the W123 back on the road by the middle of next week. Till then it sits in my garage waiting for parts.

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