The most common failure on the air pump is the bearing in the clutch. The rebuilt units seem to be OK to use and cost much less than a new pump. If you were to remove the pump and want to run without the pump you would need a shorter belt. The belt from the 87 and 88 year cars should fit without the pump. The part # is 008 997 47 92 and it is 2257mm long. Hope this helps, Robert.

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Mercedes Benz Master Tech - Retired