I love to see 1980‘s MB‘s being kept in really nice condition. They were designed with a distinctive engineering spirit. … And the 300SE is sufficiantly powered for nice relaxed cruising in not too hilly area, IMO.
First off, I assume it's OK to add the comments below to this thread because it has to do with the M103 and carries some similar problems to what Cody is experiencing, so I hope that's OK with those subscribed here.
In any event,
, I agree with the above comment; I think because the 4-speed starts out in second it can feel lazy, and it does struggle a bit on steep hills unless you kick it down to second. But I recently took it from Los Angeles to Sacramento and then west to San Francisco and then back down along the coast to Big Sur (you can Google it if you like) and back to L.A. Total of about 1,400 miles. She ran flawlessly
with only the occasional misfire at idle—which still happens. It's the strangest thing that I can't figure out. The engine seems to run really quite well, but when in Drive at idle—say, at a stoplight—and fully warmed up there is the occasional, what appears to be single-cylinder misfire, and then it's back to normal. Happens very intermittently. Maybe a fouled plug or injector...
Longer-term oil burning is not good for the cat and leads to deposits on the valves and in the combustion chambers … which, BTW, might be a reason for your cold start problems. Deposits on the backside of the intake valves and in the last part of the intake ports, which are bone dry when the engine is cold, partly absorb the first injected fuel, impeding cold starts. … You might try some Italian tune-up with a good valve-clean-additive in the fuel. …
Yes. I pour in a bottle of a fuel additive product made by Lucas Oil Products; they simply call it "Fuel Treatment" (https://goo.gl/f3AKQG
). For the last couple of years I’ve done this with every 3rd or 4th fuel fill. I do worry about the cat; the last smog check passed its nitrous oxide limit by a mere 18 parts-per-million. (In California, the max ppm is 757 and I measured 739). I fear the next one—next year—might fail.
If you see oil leaking from between the upper front cover (which carries the ignition distributor) and the lower front cover, and the valve stem seals have never been replaced, you might find out that you don‘t have to add oil anymore after taking care of these two things. The valves and valve guides may still be in order. The valve stem seals and the U-shaped rubber gasket for the front cover (and the camshaft seal ring which should be renewed at the same time) are about € 50 plus sales tax here at the MB dealer and it‘s about a three hours job.
Thanks for the guidance on the parts prices and labor time—gives me negotiating power with my mechanic.
My 300SE has 183,000 miles on the odometer, and it was manufactured in February 1989—so I guess it has the possibility of a worn camshaft. I pored through my mother’s repair records; she kept every
receipt since Day 1) and see if the valve lifters were ever done. In April 2010, at 143,925 miles, it was recommended by her Mercedes dealer, but my mother didn’t evidently want to spend the money. At that time they evidently wanted $1,750 to remove/replace the cylinder head, replace all valves, valve guides and seals and recondition the valve seats. If you’re at all interested and have a few minutes to look at the repair order and notes, feel free to PM me and I’ll send you a link to the redacted/highlighted PDF dealer repair invoice that shows the VIN and the problems/fixes; there’s lots of technician notes there that a Mercedes mechanic probably knows how to decipher.
If you hear no ticking sound coming from the valve train the lifters are still okay. If you do hear a ticking sound coming from the valve cover and your car was built before March 1989, it might not be the lifters either, but worn camshaft lobes and rocker arms. Up from March 1989 the M103 was equipped with updated camshaft and rocker arms.
At cold start-up, about a third or so of the time I hear a valve or lifter ticking loudly for a few seconds until the oil is pumped into the camshaft drip. After that there is a slight ticking at idle, worse when cold, but nothing loud. As mentioned above, the VIN indicates my car was manufactured in February 1989. I don't know what the current cylinder compression is, but the engine doesn't feel
like it's weak.