Is My Shutoff Actuator Going?
 

Last year before I had to put my 300D in storage, I replaced my oil cooler lines. In the process, I dislodged pretty much all the smaller vacuum lines near the brake booster. Thanks to diagrams I found on this forum, I got everything important connected again. The thing is, the car still takes eight seconds to shut off after I turn the key switch off. Back when I first bought the car, it took about a second to shut down. I went to Harbor Freight and bought a handy-dandy handheld vacuum pump with gauge. Doing some testing with this, I found that the shutoff actuator at the back of the IP will shut the engine off from idle with 5" Hg of vacuum. However, it takes about five squeezes of the hand pump to supply this much. That seems like a lot to me.

What I'm wondering is whether the actuator is needing more air evacuated than it should in order to function, or whether the vacuum being supplied, in terms of quantity of air evacuated over time is less than it should be. When I hook up my gauge to the nipple on the main vacuum line, I end up with 18" of vacuum, but it takes about 9 seconds to get there. The power brakes work fine as always.

I removed some old hoses and Y-fittings and replaced them with fresh hoses and tees. This got me from not shutting off at all to the current eight second time frame. I have a known vacuum leak somewhere in the lock system (will get to that later), but I have the locks plumbed to the other nipple on the big line and it didn't make any difference in the shutdown time whether I had this hooked up or blocked off.

Ideas? Info?


Edit: 1588 posts. Spanish Armada!

Check for any oil in the line connected to the actuator, brown/violet. If you see any, replace the actuator, if it's dry, it's fine.

I didn't see any when I had the lines off today. If the actuator is ok, what else might the problem be? The only thing I can think of is that somehow there is a restriction in the fitting that connects the small lines to the big one that runs to the booster.

You could have a cracked line. The lines get old and brittle, then leak. Could be a worn out ignition switch (again leaking). Also where the rubber connector connects to the SOV ensure it isn't over flexed (bent) that could limit air flow. (I had a similar experience).

I think you're on the right track.

Sounds like the actuator isn't getting enough vac, pull the rubber line at the main vacuum line and run a pipe cleaner inside, perhaps there's a slight obstruction.