Missfire and air leak on 190 carb 1989 5 speed manual

[plattssaul]

I am an apprentice mechanic that works on Audi and VW. I have recently restored my late grandfather’s Mercedes Benz 190 carb M102.924 (1989 G reg) after passing my test and it’s my first car and daily driver. Every morning when I start it up it splutters and missfires. When I put my foot to the floor the revs drop and engine nearly stalls until it has warmed even when in neutral. After a compression test (dry) the cylinder closest to the bumper was ok and others were half of what they should be and upon wet test 2 cylinders came back up and the final cylinder closest to scuttle panel stayed down. Spark plugs show car is running lean and valves are visibly burned. Some people have told me it could be the brake servo pipe which is dragging air in or possible air leak from intake or rubber carb mount. Was wondering if it could also be a fuel leak or if it’s just an air leak into the system. Manifold to down pipe is blowing but can’t change gasket as bolts are heavily corroded. Any advice from any who has worked on 190s or similar of that era. Thanks, Saul.

 

[DREAMER NO2]

New on the block then this might be of use to you https://www.startekinfo.com/service/download-document/outside/11832/# First to start with , make sure the HT side is 100% like plugs, and plug leads distributor cap and rotor are good all good ,. and that you dont have any vacuum leaks at all . Clean out the idle air control valve if the engine has one . Then come back GOOD LUCK

 

[Uncle Benz]

The rubber carburettor mounts were prone to splitting back in the day. Spraying some brake cleaner carefully around while the engine is running can be a good way to find vacuum leaks, but be careful. You’ll hear the engine noticably change if the brake cleaner is being sucked in. Sounds like you might be up for an engine tear-down though based on your compression test results

 

[Uncle Benz]

Oh, welcome too!!!

 

[rifiki]

As above with Uncle Benz. Remove idle mixture needle valve and spray every orifice (jets) with carburettor/break cleaner.
Is the float chamber at the correct level and gaskets in good condition?

 

[rifiki]

Forgot, check youtube may be some videos on 190 (W201) carburettors.