I have a '92 300 SD. I'm new to the forum but not new to my car which has some issues. But before I get into my reason for the post, I feel compelled to offer my story, as I see many others have done so, as well. Those on the forum, I believe probably already know my story of the '92/'93 W140 Turbo Diesel before I even tell it, but I'm going to go at it anyway.
In 2000 I purchased my '92 Diesel with 97,000 miles. I've always wanted a Mercedes..... and was set on the Diesel car because of their durability. The diesels were so reliable, you couldn't kill 'em they say. Originally we were looking at late 80's cars, but the newer model was available for not much more money and the newer body style. I was sold. But didn't know much about any history on the car, other than, it had all of it's maintenance records. No need to research.... It's a Mercedes!.... Anyway, the car did burn a little oil, I was surprised but not alarmed and went along, until the day the timing chain blew through the cam cover. Just like that! Long story short, I had the engine replaced with a salvaged motor (with 60,000 miles on it) 4 years ago and it's been no problem (knock on wood) and is not burning oil. The only major thing I've done since is replace the stock radio and put in XM after the power antenna ceased to operate. (I still have the original and amplifier if anyone interested.)
I've been considering selling, but enjoy the ride too much to let it go.
The door closing assist quit about 4 months ago and didn't plan to look into it until the trunk wasn't closing all the way and now I smell diesel exhaust inside the car. I'm guessing that the exhaust is working it way back into the interior through the trunk.
Following Brett's instructions, I pulled the Close Assist pump and after disconnecting/reconnecting the main power to it, found that the motor does work when I push the trunk opener button. So I checked to see if there was air coming out after pulling the HD hose, but nothing was coming out of the pump nozzle while the motor/pump was running.
I took the pump out of the box and examined the hoses to the pump motor and everything looked tight, and ran it again, there were no leaks and the screws were tight.
Not sure what to do now, my first concern is get the trunk lid to close tight all the way while I get the Close Assist replaced or further troubleshoot.
The trunk latch (on body) moves when pushed up/down, which I'm guessing is source of problem. Woud appreciate instructions/advise on getting trunk door closed all the way without the Assist operating.
Note, the lock assist pump and all the locks work fine.
The trunk latch mechanism is attached to the body by a couple of 10 mm bolts. You have to remove the plastic trim along the bottom edge of the trunk, find the bolts that hold the latch and give them a good tightening. The latch is adjustable on purpose so that the height of the closed trunk lid can be adjusted.
As far as your closing assist pump goes... You say that no air comes from the HD nozzle at all. Do all the other doors work, or is the problem isolated to the trunk line? If the air isn't going out the HD nozzle, then where is it going? There could be a blockage somewhere inside the HD lines inside the pump, or perhaps the solenoid controlled valve simply isn't operating. Could be an electrical failure of the solenoid or maybe the valve is just stuck. I can't advise on a fix for either of these two cases. What about the shut-off switch mechanism? Does it work? If the HD line is blocked, the pump should pressurize the HD line and shut off immediately (just as if you had blocked the output firmly with your thumb). The pump should not run for several seconds. You could use one of the door lines to test the shut-off mechanism independent of the trunk line (but, you'll need an assistant to close the door while you put your thumb over the door output nozzle).
BTW, if you find a problem and a solution that I haven't documented, please let me know all about it in gory detail. I'll add it to my write up. Even if you nail down the problem but can't fix it, I'd like to hear about it.
Brett
Last edited by Brett San Diego : 06-12-2006 at 11:26 AM.
Thanks for writing Brett. I'll tighten the latch. Regarding pump, sorry for not explaining better. But the motor runs, but there is no air hissing from any of the nozzles. The pump itself is not doing its thing. I don't hear anything from any hose attached to the pump. One of the hoses could be clogged. So we're gonna pull the hoses and inspect.
After removing the trunk liner to get to the 10 mm bolts to adjust the trunk latch keeper found that there was some unnecessary work involved to remove the liner and only had to slide the plastic bolt covers down to expose the bolts. Oh well, live and learn....
Did some further diagnostics on the close assist pump, that was not putting out any air. Removed the hoses between pump and relay and solenoid manifold and plugged in pump. The motor was running, but no air. Then removed the pump head and found that the impellar/vane was totally disintegrated. Lots of plastic dust.
Do I have to invest in a whole new pump or is there a supplier for impellar replacement?
Sorry to have misadvised on removing the trim. Thanks for correcting.
I've never heard of a supplier for internal parts of these pumps, but I haven't done much research myself). Bosh and Hella make the pumps. You might try contacting the appropriate one and seeing if they have any suggestions (but, they'll probably suggest buying one of their fully assembled fine products). I would say, if the vanes have worn away, the rest of the pump head is probably shot, too. Replacing the vanes wouldn't be worth it. I think you're best off with a new pump or finding a "broken" one cheap that you can swap pump heads with.
If you can take pics of your disintegrated pump head, I'd like to add those to my closing assist pump write up. You can email to me. brettchemist@sbcglobal.net
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