Should a 300TD make noise after shutdown?
 

Any owners of 300D's, does your car make any noise after you turn off the key?

My (new and first) 84 300TD makes a buzzing/whistling noise from the EGR valve area (by the hydraulic tank) after the car is stopped. I can feel the EGR valve vibrating. The vibration stops after a couple of minutes.

I replaced all the vacuum connectors in the area. No change.

It seems to me like this is where the vacuum on the engine side of the check valves leaks out after the engine is turned off. If that is true, this noise could be normal. But I don't have any other 300's to compare mine to.

I don't have any performance issues (smoking, stalling, etc) as far as I can tell.

thanks in advance

Just a thought...could it be the turbo winding down? They have a tendency to turn for a few seconds or so after the engine's shut down...good ol' momentum, eh?

I've read on this forum that you should wait about a minute before shutting off your car if you have just had the turbo going for a while...saves the life of the turbo.

no, I don't think it is the turbo
 

I live at least 5 minutes of 15mph streets away from the highway that I usually drive on (I think the turbo gets to relax before I shut the car down), so I am pretty sure that it is not the turbo. Besides the noise comes from the EGR valve, just behind the passenger headlight- at least 18 inches from the turbo.

I guess I am really wondering what happens to the vacuum that is built up in the vac system when you turn the car off. For the locks, it is trapped behind a check valve, but on the engine side of the firewall, I don't know what exactly happens. Does it immeadiately dissipate or does it leak out somewhere- like the EGR valve....

thanks

this may not be the same noise you're having, but for what its worth, my car makes a distinct knock after i shut it off, which the diesel mechanic at the mb dealer explained to me was exactly what it was supposed to do. He explained the mechanics of it but I wasn't really listening, I had to run. Anyway, if its the knock, I wouldn't worry about it.

Could be a bad diaphram in the EGR. Pull a vacuum with a MityVac or similar and see if it holds.

If the diaphram is bad, I'd pull and plug the line to the EGR to keep dirt out of the vacuum system. Otherwise replace the EGR valve.

Peter

surfblau,

I do not think any noises that go on for more than a few seconds after the engine shuts off are normal. When I shut my Diesels off they just shudder to a stop and that is it.

Normally the vacuum system stores vacuum in some containers in the volume behind the front wheels in the fenders and below the rear deck behind the rear seats. This stored vacuum is used to run locks and other stuff with the engine off. These vacuum storage containers look like a bunch of 2 " diameter black plastic spheres molded together kind of like egg cartons. There are check valves to keep the vacuum stored in these containers, and unless the act of shutting the engine down includes a feature to let air into a given set of vacuum lines, they tend to stay evacuated after the engine shuts down. So, if you have some kind of vacuum leak at the EGR valve, it is there all the time and probably not improving the car's performance when the engine is running. Try pulling the vacuum line off the EGR valve and plugging the ends and seeing if the noise persists. If so, you probably do not have an issue with the vacuum system.

In any case the noise is not normal in my experience. Good Luck and hope this helps, Jim