vacuum system part...what is it?
 

I'm in the process of upgrading vacuum system on my 1985 300td...new rubber fittings, new switchover valves, etc.

Two questions:

1) What is the plastic vacuum component located just forward of the driver's side hood hinge in the engine compartment, near the brake booster. On my car this piece is blue (I suspect it may be different colors on different models?). The piece is round (looking directly down at it), about 3 inches in diameter, with a vacuum line attached at the top and one at the bottom. The plastic part of the component is attached to a metal bracket which is attached to the chassis. There are no electrical components of this piece. What is it and what does it do?

2) I bought a bunch of vacuum stuff from Fastlane here.....one of the parts I bought came up in Fastlane's catalog for my year and model car...called a "thermo vacuum valve"...I thought this was the above part (no image available from Fastlane). The actual part I recieved is much different..... a vacuum switch that obviously attaches to the block or head and switches depending on engine temp. Two versions were available (black or blue, one 40degC, the other 17deg C). The brass threaded section of this is about 1/2 inch in diameter. The plastic component has two vacuum nipples....one extending straight out, the other at a 45 deg. angle. I cant locate this piece on my car, so I dont even know if my car has it (but it did come up as a part for my car based on Fastlanes catalog). Does anyone know about this...where it is , if all cars have one, etc.???

Thanks a lot,

Mark

Mark,
I broke the nipples off mine today! The thermo vacuum valve on my car was on top of the thermostat housing, maybe it's there on yours too? I ordered a new one from Phil for overnight delivery. See my post...

The blue thing is the vacuum amplifier for the auto tranny. If the tranny shifts OK, leave it alone.

You might want to replace all the rubber hose bits, but else it is too much of a pain to play with.

Peter

About that vacuum amplifier...
 

After i fixed the ACC vacuum leaks, now the doors dont lock....bad main valve on drivers door....I now have the door lock system blocked off, waiting for the new valve, and I still have one leak in the vacuum system, prevening the ACC from working properly:

Im losing vacuum through the main top center nipple on the vacuum amplifier for the auto-transmission (see previous posts in this thread). The vac. amp. is the blue plastic round thing with four vacuum connections, located in the engine compartment just forward of the drivers side hood hinge. There are two vacuum connections on bottom, two on top of this unit. Of the two top, there is one directly in the center, and on off center. Unless my car's vacuum system is connected improperly, the top center connection goes to the source of vacuum from one of the "t's" off the main vacuum line from vac. pump to brake booster. When I remove and block the vacuum line to the top center connection on the vac. amplifier, the ACC system works fine, as the system builds 10 to 15 inches Hg. When this line is connected to the vac. amp., overall system pressure drops to 2-3 "Hg. When I use a vacuum tester and pull a vacuum on the top center connection of the vac. amp., it does not hold pressure. I'm assuming this unit is NG and needs to be replaced....is this correct?

Thanks,

Mark