check valve help - PeachParts Mercedes-Benz Forum

JHZR2 · #1 03-04-2003, 04:17 PM

Hi,

Ordered the check valve to replace the green one on the top of the plastic thing (???) next to the alda.
Mercedesshop doesnt offer a green one. I ordered one of each color (black blue, black white) figuring mabe one would look substantially different, and if worse comes to worse, I could just use T&A.

However:

I don't know the directionality of the check valve, there is no arrow on it. I used the arrow on the check valve on the brake booster line (which I also replaced), to determine what side went towards the vacuum pump in the overall setup, and copied that, but I cannot be sure that this is correct.

Can anyone give me some info as to how these check valves are to be oriented?
Thanks

JMH

Diesel 924 · #2 03-04-2003, 05:39 PM

If I'm thinking about what YOUR thinking about, that's not a check valve. It's a damper. Your supposed to have flow in both directions. It just evens out pulsations in the vacuum source.

JHZR2 · #3 03-04-2003, 07:23 PM

hmmmm, OK, sounds good to me

Funny thing is that the whole car seemed to be running a lot better (vacuum-wise). So I guess there are no adverse effects...

Don't know why there would be a check valve on there anyway... Just the one controlling the two yellow larger diameter lines (for locks, I believe).

On another note, Is the connection that all the vac lines go through, through the firewall, used as a connection, or are the hard plastic lines continuous through that?

JMH

Fisherman · #4 03-05-2003, 12:41 PM

Continuos to various points within...

The yellow ones generally are tied to the vacuum reservoirs (rear reservoir is for locks, fender mounted reservoir is for acc, I think) and the others supply direct vacuum to the acc and other accessories i.e. ignition switch engine kill module, on a 123CD there are blue lines also that are for the seatback locks I think.

For clarification on the thingy next to the alda it is the vacuum bleed valve that controls vacuum to the tranny for shifting purposes. This valve allows air into the system when you are at full throttle reducing your vacuum to the tranny and hardening the shifts. This is so during hard acceleration you get a good hard shift and no flaring.

I have seen other cars with the green valve (may be a damper after all) on them at the point of the connection to the top of the bleed valve. This would indicate then that the valve should allow air INTO the main system but not out the bleed valve when it is open. I have never really gotten this as if the bleed valve fails it will allow air into the system and nover out because of the vacuum...

I have been running without it for some time on my car and theoretically I don't know that you need it unless it controls the amount of air allowed into the system to reduce the vacuum (hence damper).

The black line that comes off the side of the bleed valve goes into the passdenger compartment which is where the bleed valve gets it's air when it opens. Why? I have no idea, but that's what it does.

Hope this all helps...

JHZR2 · #5 03-05-2003, 01:31 PM

very useful comments... Thanks very much!

JMH