in reply to Maustin: 1986 420 SEL MB
I have the same car, but an '88.
I would check the fuses carefully again. I have encountered that the fuses on a car of this age, particularly if the car has been sitting for a while, will be weak and brittle. Replace ALL the fuses this time. I'll bet this will rectify your signal flasher problem.
The driver's door lock problem will require a new lock cylinder assembly-which should be done in the shop.
The front auxiliary fan should kick-in above the 80 C mark.
If not, the sending unit needs replacement. Monitor what's happening and at what temp.
The fan cools the car under hot temps-particularly, with the AC on.
Other things I'd check before an 800 mile trip:
1. Tires: check, visually, for wear and any bulge points. If so, get at least 2 new tires, and rotate so that the new tires are on the front. Then,, have the pressures properly adjusted while the tires are cold. For a trip of this nature, I would suggest about 30 front and 32-34 rear - depending on load. Also, have alignment (which is 4-wheel) and tire balancing checked. The balancing - to be good, which is essential on a 126 car - should be on the car, which requires balancing by a Hunter machine. However, proper on-car wheel balancing will affect the pleasure and comfort of your long trip.
2. Oil: Have an oil change done. Change it while the oil is hot. I suggest that you pick up the oil filter yourself to assure it is the right one. Use 20W-50 weight oil. I suggest Castrol GTX 20W-50 on an engine with this mileage, while subjected to the rigors of a long trip during the hot summer climate.
3. Check for oil and trans leaks. If you have the time and inclination and a few bucks, resolve them before the trip.
4. Check visually and manually all the rubber exhaust hangers. There are 4 points on this car. Look underneath the car at the exhaust system: 2 are at the rear bumper, and the other two halfway in. If they are missing or brittle, replace them yourself. They are cheap enough-and can prevent a failure resulting in tearing off your exhaust system entirely.
5. Check the shocks. If the car bounces more than once, and you want a smooth well-controlled ride, get the spec Bilsteins for the car. I would suggest HD's on the rear-since this is an SEL.
6. Check all belts and hoses. If loose (more than 1/2 inch play) on belts or appear cracked, replace them. In short, I'd replace all belts and hoses with OEM quality items. A cheap insurance policy. While you're at it, get a duplicate set - and keep them in your trunk.
7. Battery. This car calls for a group 49 battery. Get one that is NOT permanently sealed, and check the water level in it. Make sure the cable terminals and connectors are not frayed. If so, replace them as well.
8. Have the radiator and cooling system flushed and refilled properly. Hot weather is your enemy.
If you do some or all of the above, you should have a good trip - hopefully, uneventful as to the car's performance. This is a great car - if you are prudent and care for it. Good luck!