The 103 engine may need early head gasket by 100k miles, but my tech said he has seen some that have 200k on the original gasket. They could need valve guides by 100k, but equally could go to 200k - your oil use should let you know (I use zero oil in 3k intervals.) The AC may need service by 100k miles - many cars of any brand do - but likewise may go a lot longer. It is an R12 system, and when it needs work probably needs converting to r134a depending on emisson laws in your area. The AC evaporator is a difficult job and expensive when it goes. You may want to check the rear suspension bushings and arms as well - very inexpensive parts that can cause strange handling when they age. Interior plastic trim can get brittle, but the 3 items I have replaced have been easy repairs, and the parts were all less than $10 each. (A comparible broken plastic seat base item on my 88 Acura Legend was quoted as $125
! I used epoxy and screen door mesh to make an ugly repair instead.
If this sounds like doom and gloom, it isn't. All cars need work as they age, and the w124 is no exception, but my experience is it requires lots less work than any of my other cars that I kept beyond 100k miles. Many of the parts are less expensive than their Honda or Toyota conterparts, but some are more expensive. It evens out, and I will probably still be driving this car 10 years from now, and expect it to be as solid and dependable as it is now.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E