What does this part do - #8677893 Topic is solved

[scot850]

The turbo P80 99-00 use this part which Volvo calls a Master Cylinder/Servo Cylinder/Ejector.

I know it connects and sits just behind the intercooler to ETM plastic pipe and it gets a vacuum feed off it. I know it acts like a valve but not clear on what it does or how to know if it has gone bad??

https://parts.volvocars.ca/p/Volvo_2000 ... 77893.html

Part # 8677893

PXL_20230218_220142398.jpg (405.71 KiB) Viewed 545 times

Always appreciate the education!

Thanks,

Neil.

[abscate]

Same principle as the ejector fuel. “Pump “ on the left side of the fuel tank of your R , except it “ moves “ vacuum instead of fuel

In an nA car the intake manifold never gets pressure so you just hook it the brake vacuum reservoir and let it suck.

On a turbo, the IM ranges from about -0.5 atmosphere at coast to +1 atmosphere under boost

Boost pressure rushes through the top of that gadget and dumps out the bottom , and a vacuum is generated at the angled port which gets routed to the vacuum booster. Finally , you insert a bunch of small valves invented in Prague to stop the two modes of operation from interfering.

I like drilling into the operation of stuff so when you go to reconnect it, you don’t need diagrams and labels to get the hoses right , you install by function.

Yes, I still take a picture.

[scot850]

It is also helpful if you check the other side as it has a great big arrow molded into it!

Thanks,

Neil.

[rrres]

Is mine hooked up incorrectly? What I have is the angled port connected to the etm plastic pipe and the port at the wider part of body connected to the brake booster.

EDIT:
Trying to understand it...So the port connected to the brake booster always has to be in vacuum: that's easy. If engine is not boosting, the two other ports will also be in vacuum, thus creating vacuum for the brake booster port. But when the engine is boosting, the two ports will both have boost pressure.

Which way does the air flow?

Does that venturi looking thing have anything to do with creating the direction of the flow? I'm guessing that there's also a hole at the venturi's constriction to pull some vacuum....????

[scot850]

Hopefully you can figure out from this picture how it fits:

Vacuum ejector position

Vacuum ejector picture for P80 99- turbo.jpg (87.37 KiB) Viewed 455 times

Hope this helps. Back of engine is to the top of the photo. Turbo intake pipe is the hose at the bottom with a rubber hose outlet to the ejector.

Neil.

[cn90]

In the BMW E39 5-series forum, they were talking about it some 12 yrs ago.
BMW calls it "sucking jet pump":

https://www.bimmerfest.com/threads/how- ... il.578766/

[rrres]

Noob question here...under boost, would there be positive pressure at the intake manifold port?