Quote:
Originally Posted by Ansel Allen
I brought a used 280SE 4.5 about ten years ago and I had the top end reconditioned. It idled high when I brought the car and it still idleds high after the maintenance. The mechanic was adding and removing washers from a valve located in the front of the engine. He mentioned the name of the part, but I was not paying attention. I'm thinking of selling the car and want the new owner to be aware of this condition Can anyone think of what component would cause the engine to idle high or low with this manual adjustments.
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It's likely the Auxilliary Air Valve (AAV). It allows additional air during start-up. As engine warms up, it has a thermostatic bulb that causes the valve to close. It should be fully closed at 150degF. These valves are prone to sticking and not closing properly. Putting washers in to limit flow is something some do, but does not fix the problem. The valve either needs to be replaced with new or good used one(new ones are very expensive) or dismantled and repaired. It looks like this when disassembled:
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Graham
85 300D
,72 350SL, 98 E320, Outback 2.5