this post got lost over the past few days but it seems that the noise was caused by the "pin" on the crankshaft damper striking the "speed sensor". The rubber? cover on the end of the speed sensor is kinda/sorta ate up where it has been hitting (I suspect that this is the noise I have been hearing for awhile but it got a little worse after I tightened up the a/c compressor belt - must of pushed it closer to the pin while tightening the belt). I am wondering what in the world I have to do to replace this sensor. I followed it to the drivers side fender and it ties into a round diagnostic plug. I do not see how it comes out of the diagnostic plug and then some additional wires come out of the plug and continue into the wiring harness. I really don't want to have to go into replacing a bunch of this wiring just for this sensor replacement.

What all does this sensor provide a signal for? I am under the assumption that it provides the signal to the cruse control and the tach. I will probably just clean everything up and put it back together like it is - it does seem to still work because I do not have any problem with the tach.

Donnie I am going ahead and installing the new vacuum pump while I have gotten it off.
Jim

at where this sensor plugs into the diagnostic port and it does not look like this circuit goes any further. I assume that this sensor is just used for troubleshooting with the port.
Jim
'85 300D
'95 E320
'97 CRV

with the new vacuum pump and adjusted sensor bracket. Runs great and no more "loose rocker" noise. The vacuum pump was making a little more noise than the old one. Car is alot quiter now.
thanks
Jim
'85 300D
'95 E320
'97 CRV

FYI, the sensor is for a diagnostic tool and the RPM signal comes from the alternator, thats why diesel alternators have an extra wire attached compared to gas ones. Just thought you might like to know. Brian