Anti-Shudder Valve 101

[Turbo Steve]

Unlike the A-3 TDI's, VW has installed an anti-shudder valve in all A-4 diesel engines, which was designed to eliminate the little shake and shimy that sometimes is felt by the A-3's (for a 1/2 second) right after the TDI engine is shut off.

The Robert Bentley Manual uses the term - "Intake Manifold Change-Over Vacuum Control Valve", but I prefer to simply call it the Anti-shudder Valve, which is a more simplified desciption of its purpose.

In the 2000 Edition of the RB Manual (page 23-19) we read:

"The intake manifold change-over valve is a flap valve that closes for approximately 3 seconds when the engine stops, blocking the air to the engine. This reduces the suddenness of the diesel-engine shut-down. The valve re-opens once the engine has stopped."

Lubrication of the shudder valve's actuator rod as it enters the small vacuum valve is wise to do on a periodic basis, i.e. each LOF change.

[This message has been edited by Turbo Steve (edited December 04, 2000).]

 

[think diesel]

Where is this thing? Is it easy to get to? I guess it's time for me to break down and get that Bentley manual eh?

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1999 New Jetta GL TDI
Atlantic Blue/Gray studio

Mods: VW rubber floor mats, Ultra Nørsk Green Apple scented air freshener, bye-bye "snow screen"

 

[tom]

So what good is the thing?
I can live with the 1/2 second of pain during shut down. I see it as just another thing to maintain and possibly screw up!

 

[TDI Believer]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by think diesel:
Where is this thing? Is it easy to get to? I guess it's time for me to break down and get that Bentley manual eh?

<HR></BLOCKQUOTE>

Ryan,

Remember when we pulled the post IC intake hose on your car, exposing the intake of the RGR? The butterfly valve Steve is speaking of is right inside there. It is part of the EGR valve assembly.

- Rich

 

[DZLKopf]

The Red Arrow points to the actuator arm for the Anti Shudder flap valve.

DZLKopf

 

[dieseldorf]

TurboSteve, what is the suggested lubricant to use for this task?

How often...every 10k miles??

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96 TDI Wagon, ABS, emerald green
00 Jetta TDI GLS, silver arrow, CWP, LUX1, etc, etc.

 

[Turbo Steve]

While WD-40 will do the trick, I recommend a heavier lube, such as white lithium grease or a wax-type grease to stay on the slide rail of the plastic accuator rod. I've been using AMSOIL's Heavy Duty Metal Protectant on it, the door hinges, and the underhood latch assembly.

[This message has been edited by Turbo Steve (edited December 04, 2000).]

 

[blugg]

DZLKopf: Jeez, I thought I had a clean engine. It never occured to me to remove the large black plastic sound-deadening engine cover.

ButI can do that. I did it the first day I got my car, just to see what was underneath.

What do you use to clean the engine? I use Simple Green, full strength, wait a few minutes, then hose it off.

Thanks to the rest of you for identifying a gizmo I didn't know existed and telling me how to lube it.

------------------
Ted White, Bisbee,AZ
'99.5 Black Jetta TDI
'00 Suzuki SV650

 

[Nevada_TDI]

It an be use as a anti-runaway valve too. With an M5 step on brake, let out clutch, engine dies not using anti-shudder valve. With an auto trans, this valve can be an engine saver.
Turn off key, open hood and close valve manually; the few seconds this takes is generally not long enough for engine to create damage.