bypassing egr - PeachParts Mercedes-Benz Forum

brokentroy · #1 06-30-2010, 09:16 AM

Hi all, I've been searching for two days on this issue and don't seem to be able to find an answer specific to my car. Here's the scoop: I recently bought a 1983 300D. The under the hood vacuum lines were all messed up causing all sorts of performance problems. I found a diagram and got most of it reconnected properly and have had good results. However, as I was putting it all back together I noticed that the central plug (on top of the valve cover) was broken and although lines were plugged into it, it essentially did nothing. I was on another forum and someone told me to scrap everything on top of the valve cover and disconnect the egr. That's fine, but he didn't mention how to do it.

I have three lines going to the central plug. One from the egr. One to the vacuum control valve and one to the surge dampener (all according to the diagram). If I disconnect the egr and plug it up, what do I do with the other two lines?

Also, if you disagree with the other guy, what is the correct way to fix this? As stated, the central plug is busted, but parts under the black cap are fine. I plugged right into the hoses on top of the valve cover. However, in trying to fix it I messed up and didn't keep track of what hoses go to which ports on the plug, so I'm not sure I have it on there right. My broken plug looks like this:

12
345

See the pic for how the hoses are currently configured.

I wish I could find this on my own, but I can't seem to find what I need. I would appreciate anyone pointing me in the right direction.

Thanks.

brokentroy · #2 06-30-2010, 10:11 AM

correction. Plug is:

12
543

clintard · #3 06-30-2010, 12:29 PM

Sorry i cant be of help but i have same car, same year and exact same problem LOL! I didnt have any vaccum to the egr or the thermo switch. Ive taken a tin can and cut a gasket to go between the egr valve and the intake manifold which i found loaded with black crust. The gasket i made will keep exhaust from pushing open the egr and letting any more soot into the intake.

Will be watching this one

charmalu · #4 06-30-2010, 12:44 PM

This thread might be of some help

bypassing vacuum box on top of valve cover

Charlie

brokentroy · #5 06-30-2010, 02:56 PM

Ok, I've connected everything according to that thread. Thanks. One question though: What do I do with the vent line? Take off the T and plug directly into the bottom of the VCV? If so, how does it get vacuum? I pretty much have it configured this way now, but the vent doesn't open.

Thanks.

PS- Trans shift is amazing now. Had some clunkiness to it before. That's all gone now. Smooth as a baby's bottom. Not to mention the amount of power I get by hooking up the ALDA and manifold again. Amazing!

toomany MBZ · #6 06-30-2010, 03:31 PM

The vent line attaches from the lower side of the VCV and ends open in the cabin, as per your first attachment. It doesn't get vacuum, it uses the vent as a mix with vacuum to lower the total vacuum that gets sent to the transmission.
Glad to hear things are working out, the clunkiness is attributable to too much vacuum.
These cars were deigned well.

brokentroy · #7 06-30-2010, 03:33 PM

ah. ok got it now. I thought the vent line controlled the vents. lol. I'm having trouble with my fresh air vents, not opening, and I thought that was the culprit. I guess that is another issue.

toomany MBZ · #8 06-30-2010, 03:35 PM

The vent line does just as it's name implies. It's a vent to lower vacuum. It does not control the pods that are actuated when you utilize the climate control system. Two completely different systems.

brokentroy · #9 06-30-2010, 04:31 PM

Got it. thanks. My trans is working perfectly now and so are door locks etc. I will have to troubleshoot the ACC.

toomany MBZ · #10 06-30-2010, 04:47 PM

Good, if your trouble is with a push button unit (CCU), the usual issue is/are cold solder/s.
Try to determine if the pods are trying to open, but won't/can't or the unit will simply do nothing most of the time, or even change by itself.

brokentroy · #11 06-30-2010, 05:01 PM

Quote:

Originally Posted by toomany MBZ

Good, if your trouble is with a push button unit (CCU), the usual issue is/are cold solder/s.

I assume this means the solder points on the back of the unit. Had one of these out a few years ago, but haven't looked at it in a while.

Quote:

Try to determine if the pods are trying to open, but won't/can't or the unit will simply do nothing most of the time, or even change by itself.

Do I have to take the dash apart to do this? Isn't that where these pots are located? I'll do a search on here to find out more.

Right now the symptoms are: 1.) no center vents at all and 2) heat is full throttle even on the cold settings. Also, no matter what button is pushed he comes out of the side vents and the defrost. Not sure about the floor vents. Have to check those.

clintard · #12 06-30-2010, 05:42 PM

Quote:

Originally Posted by brokentroy

I assume this means the solder points on the back of the unit. Had one of these out a few years ago, but haven't looked at it in a while.

Do I have to take the dash apart to do this? Isn't that where these pots are located? I'll do a search on here to find out more.

Right now the symptoms are: 1.) no center vents at all and 2) heat is full throttle even on the cold settings. Also, no matter what button is pushed he comes out of the side vents and the defrost. Not sure about the floor vents. Have to check those.

I wish i was around to work on my car right now because this thread is getting me all excited. I cant wait to tinker and hopefully solve the same issues.

Do we have the same car Troy? My center vents do not blow, but side and defrost vents blow all the time no matter what setting (unless turned off). Im also unsure of the bottom vents. Hope you get your problems solved quickly, i will be tagging along behind you

brokentroy · #13 06-30-2010, 05:54 PM

I have an 83 300D Turbo. What do you have?

toomany MBZ · #14 06-30-2010, 10:35 PM

Quote:

Originally Posted by brokentroy

I assume this means the solder points on the back of the unit. Had one of these out a few years ago, but haven't looked at it in a while.

More on the inside, but, you get the point.

Do I have to take the dash apart to do this? Isn't that where these pots are located? I'll do a search on here to find out more.

Make a calculated observation.

Right now the symptoms are: 1.) no center vents at all and 2) heat is full throttle even on the cold settings. Also, no matter what button is pushed he comes out of the side vents and the defrost. Not sure about the floor vents. Have to check those.

Your last sentence explains, to me, anyway, it's a cold solder situation, pull the unit, pop off the back and inspect. The unit defaults to defrost, full heat to the windshield, perhaps side vents too, no matter what button is pressed.
You only get cold air from the center vents anyway, check the owners manual, if you have one.

brokentroy · #15 07-01-2010, 12:22 AM

I took the back off and resoldered all solder points. No luck. I'll have to take a look at the vacuum end. Or, perhaps, it's a bad unit. I took the glove box out and saw one of the pots. It looked ok to me. Of course, the diaphragm could be dead.