rack position sensor 603
 

Does anyone know how to removal the rack postion sensor on a 603 pump? I have some oil leaking out and I have sealed the shut off valve well and it is clearly coming out of the base of the rack position sensor. I want to remove it and put in a new seal or add some sealant to the threads so it is leak free. I have removed the connector but I am unsure how to proceed. There seems like there is a lock ring at the base. I am leaving for a trip to North Carolina on saturday and I want to have everything tip top. Any input is greatly appreciated. Thanks.

The rack position sensor apparently can only be removed once the governor is disconnected from the rest of the pump--i.e. it's not removable. You can use a small chisel or drift to loosen and remove the lockring, then clean the metal sealing ring and area underneath real well with some form of carb cleaner or whatnot. Try using a thin bead of silicone or other automotive sealer underneath the metal sealing ring, then re-tighten the lockring down. That should resolve your oil leak problem.

Thanks Casey. I did tap the lock ring to loosen it but it not seem to undo itself. It did move around a few revolutions but did not start to unscrew. Maybe I need to hold the sensor while taping the lock ring. Time to get out my third hand. After I tapped it around a few times I spread some silicone around the edges and put it back all back together. One thing seems different though. When the car is off the stop lever is all the way down as usual. When I start the car and it is idling the stop lever is all the way up. It use to hover horizontal. The car shuts off and starts fine and I am able to shut it off with the stop lever if I want but it is just different than before. Is it possible I moved something around with my tapping. What are everyone elses 603's stop lever doing at idle? Was mine normal before or is this normal now and hovering horizontal was not normal before?

Interesting question. The original IP on my TD used to hover around horizontal and never idled quite right, and in fact would run differently if I manually pulled the arm to the full up position. Subsequently, during my efforts to tweek performance, I've swapped in two different pumps and both idled smooth, with the stop arm in the full up position. It's conceivable that the rack position sensor interacts with the stop arm mechanism internally and you jostled it into allowing arm to settle in its proper position.

You may've cross-threaded the plastic threads on the sensor, so you'll have to find some way to hold it while unthreading the lockring--good luck with that.

While it's idling with the stop lever not fully retracted, pull the vacuum line to the shut-off valve. If the stop lever springs up then you have a problem with the key switch. If the stop lever stays where it was, it's a problem inside the IP. Maybe the o-ring on the stop lever shaft is too tight.

Sixto
95 S420
87 300SDL

Thanks a Casey and sixto!!! I really appreciate the feedback. It is good to know that other ip's are in the full up position too.