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Old 06-04-2002, 07:09 PM
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Join Date: Jun 2001
Location: Westchester, NY USA
Posts: 183
Two Problems: A/C & Oil Light

Hello All!

First off, I love this web site, have learned a lot and have basically restored my '87 300E completely.
There are, however, two remaining annoying problems that I'd like to fix by myself or with the inexpensive help of my MB mechanic (if the repair time is under 2 hours at $85/hr).

After doing all possible high mileage repairs at about 180K, ie: the head (gasket(s), valve guides, seats and all), the radiator, all hoses, water pump, mono belt, tensioner pully, alternator, a/c compressor, blower motor, shocks, brakes, wheels and tires -- I love the car and it drives like a dream! I removed the resistor that retards the timing 6 degrees BTDC and the car gained 11 hp, operates at a lower temp., and gets about 20 mpg, driving hard. With a perfect obsidian black exterior, a palomino interior and an Alpine/Competition MB Quart CD changing system, I want to keep the car going as long as possible. It will never be financially reasonable to sell it, so ...

Problem 1:
The engine is very tight now and doesn't burn or use any oil, and I've been running Mobil1 Tri Synthetic 0W30 (winter) and 5W30 (summer). These lubricants seem to work very well to quiet the engine substansially at high rpm's and to lower it's operating temperature (80-81 c. at all outside temp's w/ A/C on or off). However, the oil level light on my instrument panel lights up often when going up or down a hill, under heavy braking and under hard acceleration. The light comes on for a second or two and then goes off. This happens even though the oil is at the correct level (I check it often manually) and whether I use the O or the 5 weight oil. My mechanic suggested that I replace the oil level sender unit with a new one, he did, and the problem remains the same. Any ideas or suggestions? Is the viscosity of my oil too low to properly trigger the oil level sender switch?

Problem 2:
Eventhough I have a new A/C system w/ 134A, a Nippondenso condensor, and a new MB suction hose, that blows very cold air -- the system still has a problem. When I set the fan to high and the blower motor makes a lot more noise and seemingly blows a lot more air, not much air comes out of the center or side vents (during A/C or heat operation). In a fully functional system, the air should blow your hair back with the fan set on high. With my system, you can barely feel the air on your cheeks when the fan is set on high.
The pushbutton control unit works, it is new I just replaced it, I replaced the mono valve and I disconected the aux. water pump (I will replace it with a new one at the begining of the winter). My mechanic thinks that the flap behind the center vent is stuck or that its operating diaphram is ruptured or that there is a vacum leak somewhere. Does this seem right? If so, how expensive is this to fix (how many hours) and could a reasonbly handy guy (me) do the work himself? Are any special tools needed? Any opinions or help would be appreciated.

I have another subject that I will make the subject of a seperate post.
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