Fast Idle
 

Help ! My 1985 300TD 's idle is usually rock solid at 750 rpm. I noticed tonight that it is hovering around 1000 rpm. If it sits a minute or so will finally drop to about 800 or so rpm. I know how to adjust the idle but am concerned what I should look at that caused it to shift. The only thing I have done recently is change from 15W-40 rotella to 5W-40 synthetic rotella oil. I don't see how that could have done anything. Current mileage is 213000 miles. Any thoughts ?

If it helps I switched from rotella 15w 40 to the 5w 40 synthetic with no change in idle speed. HTH. Gregg

You could perhaps check the fast idle cable, it has a plastic thingy on the end where it attaches to the throttle lever, perhaps you disturbed it and it is cocked?:confused: