I understand (e.g. from this site) that timing chains can last a long time on M103's. However, since I am not the original owner of my car (1991 W126 300SE), and to be on the safe side, I decided to have the timing chain changed at its current 127,500 miles.

I had also understood that it was advisable to change some timing chain guides/rails (and maybe sprockets, etc.) in the process, so I was surprised when only the chain and tensioner were replaced. When I inquired I was told that changing guides/rails is both unneeded and a "big job" on the M103's, and that it's in fact only needed on the V8's (i.e. M116's & M117's).

Changing subjects, my exterior temperature gauge currently either is blank or displays temperatures in the 130's. I was told that the whole dashboard must come out to look into the problem.

Opinions on any of the two subjects above?

__________________
1991 W126 300SE (M103)
1995 W124 E320 Wagon (M104)

It is more likely you need to replace the sensor, NOT the display. This is about a one hour job you can do yourself. You can buy the part from Mercedesshop for about $50 or (if you are feeling a little more adventurous) you can buy a sensor without the connector from Radio Shack or other places and solder the new one on in place of the old one. Do a search for more info using a term like exterior temperature gauge or outside temperature gauge

__________________
Chip Johnson

I've tried the radio shack sensor and it doesn't work, it's very inaccurate (but it might tell you if the gauge is bad). I know enough about electronics to be dangerous, and here's the problem. All thermistors have a base reading (usually given at 72F) and a curve of resistance vs temperature or a formula, which is usually non-linear. There is no "standard" for this. I bought several thermistors from Mouser and I found two in parallel that are close from 60-100F. But still, I haven't found one that is really "right". If I get some spare dough I may buy the real thing, get set of measurements on it (not easy, but I can borrow a good temperature gauge), and then I can select the "correct" thermistor for others.

__________________
86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm