Vacuum line at base of throttle valve body -- need help identifying
 

At the base of my throttle valve body, I have 2 vacuum connections. One is shown in attached picture and the other was blocked off at the factory (modified). It is not the fuel regeneration line, as that goes from left fender directly to an intake runner.

If someone with a '90 or newer MY M103 could please take a look I would appreciate it, or if a tech could reply it would be much appreciated.

TIA :D

http://www.members.aol.com/buckweeat/regulator.jpg

Well I scoured the CD, and it states that this line connects to the 70deg C thermovalve. Unfortunately, I don't know where this valve is located since earlier 103's were modified (used to be located on head).

Could someone please help me out here. I'm almost certain this open vacuum line is hurting my fuel economy.

thanks again

You don't have a thermovalve?

Nope. :( At least not where it used to be.
http://www.members.aol.com/buckweeat/bleed.jpg

Instead I have a damn coolant bleed screw:)

Where the hell did they move it to? Nobody seems to know....

Was it ever there?

No. That pic is actually from an '86 M103, so apparently MB did a flip flop on this design. I suppose the thermovalve was in an unknown location from '86-'87? Then model years '88-'89 put it on the head.... then they went back to original design for the last three years: '90-'92. :confused: :confused:

Again, if someone/anyone has a '90-'92 300E, and doesn't mind taking 5 minutes to remove your air filter assy and checking this connection for me, I'd truly appreciate it.

Thanks again

You could buy one for say, an 89 and put it in the head. Then just connect one tube from it to the lower nipple and the other tube from the upper nipple to the egr valve on the firewall.

Good idea Cap'n, that'll be my last resort.

I take it you meant regeneration valve, not egr. :eek:

Yeah, I get my tail in trouble with those acronyms a lot!!:D :D

That should be a connection for large black plastic line that goes to the purge system check valve.
The 1990 M103 uses a computer controlled switch-over valve instead of a thermo-vacuum valve.

I have a 92 190E2.6 (103 motor). I looked at my car and the base of the throttle had two vacume ports. The top port was factory rubber plug and the other had a black vacume line with white stripe going to what looks like a checkvalve next to the ABS unit. It then became a clear vacume line with red/black srtipe going to a solonoid on driver side strut tower next to the EZL ignition module. It then leaves as a clear vacume line with a black stripe to a rubber "T" on the first intake runner. I then goes toward the distributor cap area where it travels inside the ignition wire loom on the valve cover top and goes to the two solonoids on the firewall near the battery. These solonoids go to the EGR valve and the air pump.

Rod

After reading MBDOC's post, I looked again at the what looked like a checkvalve near the ABS unit and discovered that a larger black hose came off the back side and goes through a hole into the passenger side fender.

Rod

Thanks Rod and DOC for the taking the time to look and the extensive explanation.

That helps alot! :)

That ties in perfectly with what Arthur D said about the workings of the AIR pump vacuum system in a separate thread. Apparently the whole system works in conjunction and is why I have a stored AIR pump fault code that won't go away.