1990 500 sl Questions

[dangill]

Hi!
I'm brand new to forums and would like to ask wether there are any skeletons buried in the 1990 500 sl closet.
I just purchased one with 68,000 miles in what appears to be excellent condition.
Brought it to MB for inspection and service and was told it needed a new starter wiring harness ??? and motor mount was leaking?
The harness was not in the US and estimate for both repairs was $ 1,500 -
$ 2000 dollars.
The tach reads about 2 times what it should at 60 mph. 4000 instead of 2200. The axel ratio should be 2.65 to 1.
Anyone know how to look it up?

I,m sort of a car guy, in my youth a drag racer, and have owned four Benz before the two I now own.
I,m lookimg foward to learning as much as I can about this sl as I think its
one of the sharpest styled cars I've ever seen. (that I could afford)
Thanks for all replies!
Dan

[bobterry99]

I have no idea why the tach is incorrect, but since it measures engine speed, it has nothing to do with the rear axle ratio.

The engine mounts are filled with fluid. You can save considerable money buying them on Fastlane and installing them yourself.

[bwheitman]

You are going to love owning a 129 car, they are the Best!

Motor mounts are typical to fail and are filled with fluid. Mercedes considers this a wear item, but when replaced your car will almost feel like new again. If you are having someone do it besides the dealer make sure you/they check the tranny mount too, the flex discs, and the exhaust hangers. The engine literally sinks lower and stresses these items as well. After the mounts are replaced loosen and re-tighten the exhaust hanger that is on the back of the tranny to re-set the exhaust system. Not doing so will result in stress on the headers and pipes themselves.

The engine wiring harness in these cars are known to fail, so replace it, because when it does it can take computers with it, making the repair very expensive.
It can leave you stranded.

Another item to check in these cars is the steering, I had a vibration in my car and it took months to find, it was discovered when I noticed the center link had a broken boot, I replaced it and all the vibration is gone, it is a good idea to replace the steering dampner too, those are cheap about $25 so it is an inexpensive item that helps your steering feel newer.

Also be sure to check the front of your condenser/radiator. The 129 cars seem to collect a lot of debris in there and it can build up. Keep it clean so that your car will run cool. Changing the thermostat is a good idea too, if you replace the anit-freeze go ahead and do this.

Make sure you have the Original MB wheels. Aftermarket wheels do not have the correct offsett and can damage your suspension. If you change them out, change them with MB wheels. An incorrect offsett is dangerous and will make your car handle differently.

If you have not done so already, change the headlight bulbs whether they need it or not. The problem with these is the orignial bulb sometimes melts the plastic around it's mounting area, making removal very difficult unless you can turn them on to heat them up. If it is burned out you can't heat it up, making removal very problematic. Turn the brights on for about 2-3 mins and they will pop right out. Otherwise if you wait until they burn out it is not fun. This happened on my drivers side, so I replaced the passenger side while it was still working.

Check the car for any places where rust could be starting, remove the jack hole covers, you will see where it might be starting because the jack chips off the paint when you put it in. Clean around it with a wire brush and apply paint to protect it. This is the only place I could find slight rust on my car.

The rear-view mirrors on these cars always wobble, don't go and buy a new one, more than likely it is not broken, just loose. Do a search on the forum to get instructions on how to remove it and you will be able to tighten it up.

Make sure you have your radio code if you have the MB radio. Also make sure that anytime you disconnect the battery that you re-sync your windows. They go down about a quarter inch when you open the door. If you don't re-sync them you can damage the window frame or cause it to go out of adjustment. The side window in the 129 are amazing with all the ways they can be adjusted, they are adjusted to fit the hard top and the soft top is adjusted to fit the windows.

If you just got this car, be sure to change all the fluids, including the brake fluid, this will give you a fresh start. Follow the maintenance manual and you will have a trouble free relationship with this car. Good Luck and Happy Benzing! If you are not an MBCA member be sure to join! Free technical support and support from other members is really nice!

Best Regards,