Slow shut down '90 300D - PeachParts Mercedes-Benz Forum

2.5Turbo · #1 05-24-2007, 10:56 PM

I was on a long road trip last weekend, and once when shutting down it took about 3 seconds for it to shut down. It did this every time from there on out. When I got back home, I whipped out the mityvac thinking vacuum leak. Sucked down the vacuum system and everything held 20" of vacuum nicely. Then I noticed that the vacuum line for the shutoff switch gets its vacuum from the brake booster line. The brakes work very well, but just to check I disconnected the brown shutoff line from the fitting and attached the mityvac. Everything was normal. I then hooked up the mityvac to the brown line with the car off and started applying vacuum through the ignition and into the IP. The stop lever would go down partially, and the vacuum would not build past 5 in/hg no matter how fast I pumped. I lightly helped the stop lever down further with my hand while pumping, and at the point where it starts taking effect on the engine fuel delivery it started to hold vacuum and went down all the way without my assistance. It held vacuum fairly well, definitely enough stop the engine. To eliminate the lines or switch, I hooked the mityvac directly to the shutoff device. Same results. I also tried it with the engine running. I shut off the ignition and of course the engine kept running, albeit with a bit lower RPM because the EDS was no longer affecting idle speed. I applied vac to the shutoff device and I got the same results. The engine speed would slow down gradually for about 3-5 seconds until it stopped. I don't have that much of a problem with it being like this, but today in a parking lot it almost didn't shut down on its own...so I'd like to get it fixed

. I'm thinking a diaphragm in the shutoff device on the IP has split or something. Is that part that difficult to replace, or should I let the indy do it?

sixto · #2 05-25-2007, 01:40 AM

There are two screws holding the shut-off actuator to the IP. One is easy to remove, the other is a PITA because it's hidden by the control rod sensor connector and ALDA. With a couple of big wrenches (24mm and 27mm?) or channel locking pliers you can loosen the ALDA and turn it so it's not in the way. Turning the ALDA will not affect its setting. That might be all you need for access.

I've yet to see a control rod sensor bayonet lock that released the connector. After a lot of fiddling with it I was convinced that breaking the bayonet lock was the way to go. The connector hasn't come off in a few thousand miles with no bayonet lock.

Sixto
93 300SD 3.0

2.5Turbo · #3 05-25-2007, 02:38 AM

Cool...did a little research and found out that on the 617 IP's it's on the back as opposed to on top like on our 60x IP's. Looks like I'll be browsing Fastlane soon

. I assume the risk of runaway due to impropper installation is still there. Lots of the DIY pages explaining how to avoid this potentially engine grenading situation say to pull up on the device before securing it to the IP. This should depress the stop lever when properly installed, right? I'll take the turbo pipe off and have a piece of wood ready when starting

TimFreeh · #4 05-25-2007, 07:47 AM

Quote:

Originally Posted by 2.5Turbo

I assume the risk of runaway due to impropper installation is still there. Lots of the DIY pages explaining how to avoid this potentially engine grenading situation say to pull up on the device before securing it to the IP....

I did this job about a year ago and I remember having the same concerns, but when I installed the new shut-off valve it was not an issue. I think they changed the way the shut-off valve connects to the fuel rack on the OM60X engines to eliminate the possibility of a run-away condition.

gsxr · #5 05-25-2007, 03:52 PM

Remove the ALDA so you access the bolts that hold down the shutoff pod, otherwise this job is a nightmare. Replace the O-ring seal as well. Otherwise it's fairly simple. make sure you get the new one properly attached to the lever inside. Before you re-start the car, apply vacuum with the MityVac to the new pod and make sure the stop lever has the same travel as it did with the old pod, before you touched anything.

2.5Turbo · #6 06-01-2007, 08:13 PM

Well I got the new valve yesterday and installed it today. I removed the ALDA which required the removal of the CC actuator and washer fluid tank for wrench clearance. I don't think the clearance is a problem on the 603 as the extra cylinder pushes those devices back a little bit, and the ALDA is relatively clear. And Sixto, I got the bayonet lock off of the control rod sensor plug fairly easily. It just clicked CCW a little bit, and the plug popped right out with a little wiggling. The ALDA took quite a bit of force to break free, but once it came loose it was easy to take out. After taking out the 10mm screws, the oily valve popped right out. I made sure to get the stop lever connected to the valve when I installed the new one, and had a block of wood ready in front of the turbo inlet just in case while starting. I had my brother start the car and it stayed right at idle. Then we shut off the key and it shut down immediately.

I love it when fixes are cheap! Many thanks to all who gave advice!