83 300D - Intermittent tach, no cruise and 8 amp high beam fuse ?
 

Where should I start to look ?? One minute the tach is dead, the next it's at 6000 rpms and the next it's spot on. Also the cruise is inop. I checked and changed all the fuses for age sake. Also, I have Euro headlights. I installed PIAA Hyper White bulbs in the headlights & fogs. The right high beam was out and I assumed the new bulb was bad. I checked the fuses and found the right high beam fuse blown. I changed all fuses and I've used the highs for 5-10 minutes at a time since and they didn't blow so I assumed the fuse was blown before. Can the high beam circuit handle more than the 8 amp fuse thats there now ?? TIA

Anyone ???

Use the search function. This question is asked by EVERY first time MB 617 engine owner... well, those whose car has a tach.

The gist of the cheap fix is to stuff something springy but not conductive between the case and the board of the tach amp (round spin-on thing behind the left headlight). I used felt furniture foot pads.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

Cruise control problems are frequently the result of a faulty cruise control amplifier. Click this link for an illustrated repair procedure.