We have been hearing ticking rattling noises coming from the front of the engine on our '96 E300 for more than a year now. Have ask every mechanic their opinion and the general consensus was that to put the car in a shop to diagnose would cost hundreds of dollars and that it is best to wait until a problem occurs. Yesterday a problem occurred; while driving cross country engine code P0400 came up, no power brakes, AC vents stopped working, shifting became hard and the intake manifold valves stopped working.

We were lucky, I hope, that the vacuum pump did not explode. The engine actually sounds better now without the rattle and the car ran great for the rest of the trip home, more that 7 hours of running hard. (The car now has 215,000 miles on the dial.)

Passed through Dallas, hours later, where there are several parts suppliers. One had the part that I now have.

Questions: Do you guys have any suggestions or advise on replacing the pump? Are there any hidden issues that I should be aware of? Is removing the radiator required?

Will post pictures of the work in progress.

Thank you in advance for your input.