1972 Mercedes Benz 220/8
 

Hello,

I have a 1972 Mercedes Benz 220/8, 4 cylinder, automatic, gas, with a single stromberg carburetor. I’m having some problems with it, my parents don’t want me spending a lot of money on it, they also want me to sell it, but I would like to keep it and get it working so if I do sell it it will be running better, and I will have some knowledge on working on Mercedes cars.

If you know how to solve one of the problems PLEASE LET ME KNOW. thank you.

1. When the engine is running there is smoke coming out of the valve cover.
2. The exhaust is dark gray.
3. The engine makes a little knocking noise, when running.
4. Engine doesn’t respond well when I put on the gas, while in park.
NOTE: I just replaced the fuel pump and some of the fuel lines.

Thank you in advanced.

spencerbandit88

RE: 1972 Mercedes Benz 220/8
 

do check compression test
piston ring loose got smoke at exhaust
oil change with engine cleaning see can help the valve cover smoke
look inside carburator see have the gas dripping or the choke need adjusted
just simple things......[:-]a lot of people disagree...
any how i dont care it can help but i did it a lot.....:D

RE: 1972 Mercedes Benz 220/8
 

Hello,

How can I tell if there is a bad valve stem seal or a bad piston ring(s) just with a compression test.

I was told do the test and if one is way lower than the others then put a little oil into the cylinder and turn the engine by hand and do the test again and if the number is higher than you have a had piston ring, and if not then you have a bad valve stem seal. Is this true?

Thank you again,

spencerbandit88

And bbs138 I have a Stromberg carburator in the car, how can I check for gas gripping out, and the choke?

RE: 1972 Mercedes Benz 220/8
 

You have oil blowing-by the rings and maybe valve stems as bbs138 explains and you need to address that.

But have you replaced the PCV valve? Blow-by gases from the crankcase should go back into the air intake through the PCV valve. If it's stuck it has to go somewhere and certain laws of physics won't allow all of it back into the crankcase so some squirts out of the valve cover weak points. It won't solve your problem but it's easy to check and cheap to replace. If it has never been replaced, it needs to be. They don't last 30+ years.

RE: 1972 Mercedes Benz 220/8
 

if you will put abit of oil inside the cylinder (say about two spoons) and the compression goes high... there you go, it's the piston ring.
but if the compression value is the same, then you're looking at valve seat, valve guide or valve seal.

RE: 1972 Mercedes Benz 220/8
 

Hello,

I did a compression test on all of the cylinders.
Here are the results of the test.

7,11,11,10 (kg per cu. cm.)

What would cause it to be high?

Thank you

spencerbandit88

RE: 1972 Mercedes Benz 220/8
 

between 8 to 12 is fine. was that a wet compression test or normal?

you should worry more about the cylinder #1 which is lower than the rest.

the smoke that's coming from the valve cover is the blowby gas from the cylinder. try checking the PCV valve (positive crankcase ventillation). the cause of it was piston ring or valve seat/seal.

dark gray smoke is oil and air leak problem. again, it could be the #1 cylinder piston ring. black smoke is too much fuel (but you don't have this). check for air leak. pour some water on areas that you suspect the external air could be drawn in by vacuum from the manifold or hoses. if the engine suddenly vibrates or stall... then you are one step closer.

knocking noise could be from cylinder #1? if you are a doctor and you got a stethoscope, then try using it. if not, any long metal rod can do... enough to scout for the knocking area. connecting rod bearing can make knocking noise.

about the acceleration response, it's the carburator. stromberg is an easy design carburetor... not much inside. take them apart, clean, and have a good time doing the real jigsaw puzzle.

the fun has just started ;)