ok since im about to start tearing up the engine they ware few things that i wanted to replaces and those ware. injectors,cap and rotor,timing chain,valve seals,cold valve,and crank shaft cover seal the thing is when my car worms up and u take the oil cap off there is steam coming from it and my spark plugs gets fueled ok so i thought its valve seals so il change them but as i keep searching on gogle that steam is called blowby and that is results from worn o rings would that be my problem the car has lots of power the only problem is when going from the dead stop it will have slight hasitation from 500rpm to about 1000 then it goes normaly i will do compression test and see how it goes but what u do u guys think about that i mean if the o rings are gone il just take the hole engine out take it apart change rings head gasket resurface the block and polish it get new rods and maybe pistons its a lots of work do u think its worth all of this or should i just go with my old plan ??
Blowby is not caused by o-rings, it is caused by worn piston rings. The M103 has a tight crankcase so removing the oil filler cap while the engine is running should cause the idle to change and air sucked *into* the oil filler opening, not coming out.
Still, unless the engine has 250k miles, hasn't had regular oil changes, or has been severely overheated in the past the bottom end should be fine. You should check for a clogged or kinked breather hose, the smaller ell-shaped one that goes between the rocker cover and the intake manifold. That alone can cause big issues.
When I swapped the 135k mile 300E drivetrain into my 260E I wondered about doing bearing and rings at that time. Every Benz-familiar machine shop I talked to said don't do it. Totally unnecessary. So I did the head only and have not been sorry. At about 196k now with no worries or oil consumption or whatever.
So don't mess with the bottom end unless you have reason to believe it's toast. Oh, of course I did a compression test on the 300 engine before pulling the head. Numbers looked good and even so I took my chances. I won.
when i open the cap the car is still idling the same is that normal? and the car has only 120k i have taken care of it and used the best oil on the market and if the pistons ware worn out shouldn't the car be low on power and maybe smoking? i will make a video of it and just to show people i bet lots of w124 has the same thing happening to them my father is an experienced mechanic he test drove the car and he said that the car pulls hard like it should except for the lil hesitation when going from stop so he don't think its my pistons he will check my compression this weekend to see if its low and the gases from exhaust i smalled them and they smell clean like in new cars year and half ago the car had the same steam coming from it and it past the emission close to my sisters ml320 results. And when u rebuild ur head did u do it ur self or u took it to the shop and how much did it cost u ?
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