190E oil consumption fix, stripped engine mount bolt
I recently worked on a friend's 1990 190E 2.6. Here are some things i did:
It was burning lots of oil most noticeable at start up and would not pass smog. I found a MB TSB from May 1992 that addressed the most common cause of oil consumption in this engine and it also lists your engine (102.961). Apparently these engines had poor valve stem seals. The new replacement ones are made of Viton and will last longer and work better from the start. Nevertheless, i performed a compression test on each cylinder before digging in as I wanted to see how the sealing of the rings and valves was. compression was high and consistant as with your car so i went ahead with the seals. I was able to borrow a valve spring compressor from Autozone for free. They have a great tool loaner program with no questions asked except a deposit (you don't even need to buy parts from them! Dont forget to compress air in the cylinder your working on or you could drop a valve. Make sure that cyl is in TDC or the crank will rotate from the compressed air. Before loosening the valves hit the top of the valve retainer with a soft dead blow hammer. you need to or else the keepers can't be removed. Put clean rags in the area so you don't drop a keeper into the engine. A magnet should be handy.
Anyhow after an afternoon of work and several months gone by he no longer needs to add oil. Before this he was told by a mechanic that it would cost $1200 to redo the head. I can't believe how easy it is to get ripped off. The valve stem seals are very2 cheap. It's a non brainer if the cam is coming out anyway. MB has another TSB about the camshaft lubrication oil pipe. In July 1991 they started using Locktite 642 on the screws holding the pipe. The screws on engines before this date tend to loosen causing lubrication problems for the cam. funny enough one of the screws I undid felt only hand tight. were any of yours loose? Don't forget to degrease the holes before putting back the screws. One drop of loctite per hole is enough and you need to wait 15 min after tigtening before starting the engine up. Better take care and respect MB torque value on these. it's easy to over do it with little screws (strip them) especially when you are thinking about how they got loose the first time.
There is also a 1989 MB TSB on your camshaft.
Finally I replaced the tensioner, smog pump, alternator, engine mounts and the trans mount. On this particular car the engine mount bottom bolt was a 8mm allen. It was on so tight that even after hammering it to set up a vibration and lots of WD40 it stripped. I'll share a trick with you on this one for anyone interested. Just take a 15mm 12pt socket and hammer it onto the bolt. the 12pts grip in perfectly and the bolt came of with a breaker bar. I can't imagine why this bolt was on so tight in the first place (impact hammer?). Now MB only stocks regular bolts instead of allen head when you buy new ones as i found out after stripping one of the existing ones.
Good luck and thanks for you advise to me earlier today about the brake booster,