1981 240D vacuum issues - Page 4 - PeachParts Mercedes-Benz Forum

tyl604 · #46 02-14-2019, 05:27 PM

Ouch.

vwnate1 · #47 02-14-2019, 07:50 PM

There are multiple plastic pipes for the vacuum, they're all color coded .

The two yellow pipes coming out of the firewall, one goes directly to the vacuum resivoir in the trunk, the other goes to the driver's side door where there's a control valve connected to the driver's door lock button .

Begin there with your Mity-Vac tool ~ it will take a lot of pumps for the pipe leading to the resivoir to show resistance so don't quit too soon .

The other pipe when pumped will cause the doors, trunk and fuel filler flap to lock or unlock depending on the driver's door lock button position .

I hope your shift went O.K., 13 hours, gah .

Don't forget it needs a valve adjust too ! , special tools necessary .

pj67coll · #48 02-14-2019, 09:02 PM

I'm confused. I see 81 240D in the sig. 81 240D's have no EGR.

- Peter.

unknowncross · #49 02-15-2019, 02:16 PM

Thank you VWnate! The shift went by excruciatingly slow, but I do a 16 hour shift every Thursday... The advantage is that being a security gives me a chance to catch up on Netflix...

And yes, I am dead freaking tired.

Thanks for the information on those vacuum lines! It's unfortunate but those two lines you mention (the vacuum reservoir and lock lines) are actually the two that had a leaking Y junction. I had attempted to cut the junction back to good rubber (previous owner had taped it with electrical tape, it did not work..) but it was split all the way down the middle. I just capped off the feed line to that junction instead. I will have a new junction arriving hopefully this week.

The correct vacuum line is part number 0001581435 and 1179970982 they are 1mm ID and 3.5mm ID respectively, which sounds about right, correct? I'm ordering 3 meters of the smaller stuff and a meter of the larger one. That should be, by my estimate, plenty to replace/patch the areas that need to be done that I have seen so far. I do recall testing both those lines and I believe they both held vacuum, but I am going to test them again just to be certain.

And pj67coll according to everything I've read, even the factory manual, the US version SHOULD have a EGR valve. However as you stated it would appear mine does not, so perhaps it was a kind of mid year switch they did where they started equipping them at some point during 1981? I indeed can't seem to locate anywhere that the EGR would have been, I assumed there had just been a EGR delete done already on the car.

tyl604 · #50 02-15-2019, 02:33 PM

Very interesting. If the 240D had the EGR, would it be a black box on top of the valve cover like in the pic of my 300SD?

When I look at the top of your valve cover, I do not see an indication that the black box has been removed. I could be wrong.

pj67coll · #51 02-15-2019, 02:42 PM

Quote:

Originally Posted by unknowncross

And pj67coll according to everything I've read, even the factory manual, the US version SHOULD have a EGR valve. However as you stated it would appear mine does not, so perhaps it was a kind of mid year switch they did where they started equipping them at some point during 1981? I indeed can't seem to locate anywhere that the EGR would have been, I assumed there had just been a EGR delete done already on the car.

I have had two 81 240D's. Neither of mine had the weird mess on top of the valve cover that yours has. Are you sure someone wasn't trying to do some DIY "enhancements" in it's past?

- Peter.

pj67coll · #52 02-15-2019, 03:15 PM

I've just realized that part of the stuff on top of your valve cover that mine doesn't have may be because yours is an auto. Mine is a manual. I've found a blog online that seems to display an 81 auto vacuum routing. Might be of use.

https://blog.*******.com/mercedes-w123-240d-vacuum-overview

- Peter.

unknowncross · #53 02-15-2019, 10:32 PM

@Tyl604 - From my understanding the EGR would be located on the passenger side of the engine near the exhaust manifold. Mine simply doesn't seem to have a space for it. Also on the 81 240Ds they indeed did not have the black box you're referring to. My understanding is that is just a cover for the valve I have on top of my engine, I could be wrong, but there indeed was no black box or cover on top of the valve cover at any point.

@pj67coll - I belive you are correct about the mess on top of the valve cover being due to the automatic transmission, manual transmissions don't have any vacuum lines (unless i'm mistaken?) so there is no real need for the throttle controls 3/2 switch over valve (the thing with 3 ports on top of the valve cover) From my understanding it is only required to deliver vacuum to the VCV valve, which is then supposed to send vacuum to the EGR (Not equipped on my car) and the transmission. That vlof post is the one I believe I had referred to earlier in the thread, the website name is blocked out though... Does the forum block external links it seems?

If anyone notices any discrepancy in my understanding of the vacuum system then please feel free to let me know, this is just what I can gather from bits and pieces I have seen in other forum post and some blogs and of course youtube.

pj67coll · #54 02-15-2019, 11:43 PM

Quote:

Originally Posted by unknowncross

@Tyl604 - From my understanding the EGR would be located on the passenger side of the engine near the exhaust manifold. Mine simply doesn't seem to have a space for it.

Forget the EGR. You car never had it. Same as mine.

- Peter.

Alec300SD · #55 02-16-2019, 12:36 AM

These pdfs may help:

https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/615/07-150.pdf

https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Chassis/80-901.pdf

Here is the FSM link as well:
https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/matrix6.htm

unknowncross · #56 02-16-2019, 12:32 PM

Thanks Alec300SD! If the diagram you sent me is accurate, it looks very similar to mine, then that means I shouldn't have a capped off line on 3/2 valve, and the transmission should be connected directly to the 3/2 valve and not ran through the vcv? I'll see if I can figure out if that will work, and see if I have any extra lines that aren't shown.

One issue I have seen with most diagrams is that my lock system does not come off the main vacuum line, it's T'd off from one of the lines on the VCV.

Alec300SD · #57 02-16-2019, 01:05 PM

I believe you are correct, at least that is how I interpret the diagram.

Note: The switchover valve may have been bypassed because it has failed.
I believe these switchover valves might be NLA.

vwnate1 · #58 02-16-2019, 01:18 PM

The yellow central locking pipes *must* be connected to the primary vacuum source, it's clear your car has been messed with by someone who doesn't understand it very well .

If the color doesn't bother you, buy at least 8' of the blue silicone hose, it will fit every vacuum connection in the entire vehicle and never rot, fall off or leak vacuum .

If you car was sold new in Nevada, is -may- be a "29 state" car, they have slightly different and less complicated emission control systems .

DO THE BASICS then once it's running properly and the engine shuts off before you can get the key out of the ignition, then and only then move on to the central locking and HVAC systems .

A good running 240D will never be a ball of fire but it *IS* a joy to drive and amazingly economical .

Ping me off site and let me know where in The Silver State you live, I *may* have some parts help for you .

tyl604 · #59 02-16-2019, 03:50 PM

Switchover valves are readily available at the dealership.

I cannot think why the vac line from the tranny modulator would not go to the VCV. Please let us know as you dig deeper into this.

unknowncross · #60 02-16-2019, 05:03 PM

vwnate1 since you ask I live in Las Vegas.

Where can I find this blue silicone hose? color doesn't matter to me at all, I was planning on ordering some line off of ******** but if that stuff is that good and versatile I'll just order a bit of that. The previous owner told me he had messed with the vacuum lines, and routed them according to his other car. Which is a 1983 300TD station wagon. I'm not sure where the car was originally sold, so it's possible it was a Nevada vehicle from the start. The vacuum lock system is something i'll fix when I get the time, i'm much more concerned with the transmission shifting properly first. I took it for a long drive yesterday and it started having issues, which I believe to be related to the vacuum system still.

And tyl604 I believe the modulator valve was connected to a T at some point from the VCV... But at the current moment everything on the car goes through the VCV. Literally every vacuum line is ran through the VCV.