switchover valves - PeachParts Mercedes-Benz Forum

kmaysob · #1 03-10-2004, 11:10 PM

i belive thats what the liitle valves on to of the valve cover are called. anyways what would it cost me to get new ones of these. i think thats the problem with my tranny not getting first gear. my question is does anyone know how much they cost bran new, and do you think this could be causing my tranny problem. when you shut the car off you can hear it leak there. i couldnt find anything on fastlane. any info would be appreciated.

wolf_walker · #2 03-10-2004, 11:20 PM

The white one's on the valve cover? Called 3/4 valves sometimes I believe, and cost more than they should, check fastlane(link at top of page).

Near as I can tell on my 83 there sole reason in life is for the EGR system, and they can screw up the shift vacuum circuit. I therefore removed mine, as with the EGR. This is all for offroad use only, yadayadayada...

kmaysob · #3 03-10-2004, 11:27 PM

when i unhook the line to the egr i can put my finger on the vac line and i feel nothing. i even tryed reving it

wolf_walker · #4 03-10-2004, 11:34 PM

Normal when the vac system is a leaking mess, which most of them seem to be unless someone with a clue has had there hands on it. I'd just bypass them alltogether. If you look at the hose diagram and routing, you should be able to see what needs to be bypassed. They definantly like to leak if there worn.

kmaysob · #5 03-11-2004, 12:44 AM

yea the seals are worn. i tested with mittyvac. would it lose performance if i remove those. will it shift differently?

wolf_walker · #6 03-11-2004, 12:58 AM

Should not loose performace, and will likely shift better than it does now, leaks are bad.

All they really do is control the EGR valve relative to the throttle position. If you look at that big black wedge shaped cam hooked to the throttle that works the valves, one is open and one closed at idle, and there is another combo of open/closed at other throttle positions.

IF, and I do not believe this to be the case, they have anything to do with shifting, it's not worth the $100 it would run for two new ones. I really wish someone would explain it if they DO have anything to do with the trans. Looking at the FSM over and over, I don't see that they do, and mine has suffered no ill effects from it.

And loosing the EGR is better for power and for NOT filling your intake with crud anyway. Know that it's illegal for on-road use, a factor if you have emmesions testing for diesels in your area.

I removed the valves and the little group of hoses that hook to it on that rubber connecting block all together. Cleaner that way.

kmaysob · #7 03-11-2004, 02:03 AM

do you still have them? do you stil have the rubber block that the vac. lines connect to?

wolf_walker · #8 03-11-2004, 02:31 AM

The valves were shot, and I'm yet to see any in a salvage yard that were any better. I still have the rubber block and whatever lines were hooked to it. There pretty easy to come by in salvage yards.

These valves are something I asked about ages ago and never got an answer about as to them being strictly for the EGR or not.
I really wish someon would confirm what I've concluded as true or false, though I'm 90% sure I'm right that there EGR related only.

kmaysob · #9 03-11-2004, 04:10 PM

ive looked in junk yards and the rubber block is gone off them all. maybe people take them because the heat here dries theirs out?

adamb · #10 03-11-2004, 05:53 PM

I am sure that those valves are for EGR only, so disconnecting them and plugging the lines is the way to go, IMHO.

wolf_walker · #11 03-11-2004, 05:58 PM

Quote:

Originally posted by adamb
I am sure that those valves are for EGR only, so disconnecting them and plugging the lines is the way to go, IMHO.

Good, thank you.

kmaysob, if you'd like a photo of mine with the valves completly removed, the routing of the vac hoses, let me know. If you really, really want to replace them for some reason and need the rubber connector block, let me know and I can send you mine, assuming it's still in the trunk. I really think you should ditch them all together though.