D5 "Dump Valve Sound" / Slow Turbo Response Cure
 

As discussed in my previous posts and after lengthy investigations into why my car was producing this overboost and Dump valve "PSSSSSSST" sound everytime i revved or changed gear, the problem has turned out to be so simple yet so very easy to cure.

I cannot take full credit for this thought as i had alot of help fault finding, result comparisons and advice from Outnumbered, Hobbyhorse and Bernard 333. So big, big thanks to you guys!

Right here is a quick how to: (I cant take credit for the photos as they are the work of the very helpful Outnumbered, Thanks again)

Tools Needed: 1 Big flat head screwdriver, 1 Torx 30 Screwdriver, 1 Can of Brake/clutch cleaner (or similar), 1 Small screwdriver & 1 cup of tea to admire your handy work on completion


1) Remove the Inlet pipe by unscrewing the jubilee clips pointed out in the picture below

http://img17.imageshack.us/img17/888...1041300042.jpg

2) Once this pipe has been removed you will not have much better access to the Boost control valve or turbo governor (many different names) shown just behind the pipe below.

http://img59.imageshack.us/img59/484...041300043a.jpg

3) Unbolt the 2 screws shown in the image which hold the Control valve to the engine block (Torx 30 screws).

*IMPORTANT* As shown below, make sure you put a rag or cloth down onto the starter motor terminals because when you are unbolting the bottom screw your screwdriver can quite easily short out on the positive terminal.

http://img815.imageshack.us/img815/2...1041300045.jpg

4) Pull out the controll valve so that you can get easy access to pipes and connector attached to the unit. Remove the pipes and connector shown below making sure you note which pipe went on which input (they are labeled "VAC" and "OUT"

http://img828.imageshack.us/img828/1...1041300047.jpg

5) This bit is the only fiddly bit. *CAREFULLY* remove the small black square cover on top of the boost control valve (shown below) with a small screwdriver or knife (there are 4 small lugs holding it on) *be careful also not to snap the supporting legs, although they are quite tough*

http://img43.imageshack.us/img43/491...1041300049.jpg

6) Once the cap has been removed you will see a small, very fine plastic mesh. This is where the vacuum is diverted to release the boost pressure on the turbo. As you can see even the slightest bit of muck can reduce airflow out from this. Using the Brake Cleaner (or carb clearner) Give the mesh a good long blast from the top and quite close to make sure all the little bits of crap are removed. The mesh, when clean should become a white color.

http://img192.imageshack.us/img192/2...1041300048.jpg

7) On the "Out" Leg give a gentle blow until air is felt from through the "Out" leg, just to dry it out and make sure there's no crap in there.

Fitting is the same but in reverse :)

I hope this helps people that were in my boat, as we have discussed in previous threads, i wouldnt like to think how many peple have replaced this valve for the same reasons i would have, only to find they could have cleaned this mesh and problem solved!

I cant gaurantee this will work for everyone as there maybe other vacuum related issues going on such as leaky engine pads.

But i would recommend this to anyone doing routine maintenance on thier car as my turbo response was DRAMATICALLY increased and the "dump valve" sound is GONE!!!

Once again i cant thank Mike (outnumbered) enough for his sound advice, willingness to go out and help (leaving his breakfast go cold) and for the pictures! Also to all the other guys for thier help and advice!

If this saves one more person from a trip to the garage with countless diagnostics being performed and parts changed being changed at rediculous costs then it goes to show just how useful and helpful this forum and alls its members are!

Great post, RAN.
Respect to you, Mike, Hobbyhorse and Bernard 333.
Gunna do mine tomorrow.

I also invested a tenner in a dry vacuum gauge and T-piece from Flebay - to check my engine pad diaphragms for vacuum hold.

http://rover.ebay.com/rover/0/e11003...SA%3AGB%3A1123

one remark - you don´t have to completely unscrew the bottom screw. As seen on the third photo the screwholes are not complete so the thing comes out after the screw is loose. The top screw has to come out though. Reduces the risk to loose screws into the engine compartement.

Thank You also for the useful post. I will also do mine today, interesting what improvements if any will follow.

Have you been suffering from overboost and "dump" sound too?

Absolutely brilliant guide matey many thanks. I shall give it a go a bit later and report back with the results

i have heard some "psssst" like sound but don´t have any error codes, messages or power loss. I also can not tell if the turbo response is slow, since it was the same all the time, maybe after the clean up it will change and I will notice the difference. My problem is still the exhaust like sound from the inlet manifold so don´t know if the governor clean up will cure that (I doubt), but it will certainly do no harm. I have taken the governor off in the past but since it looked ok I didn´t do anything with it. Now I am wiser thanks to you.

It'll be interesteing to get some reports back as i cant explain how much of a difference it has made to my car. Th worse part of it is, this fault will not produce any fault codes!

The turbo just overboosts and spools at the wrong times and as a precaution the ecu cuts fueling etc and slows everything down thus slowing the car down!

After the valve was free'd and could release all that vacuum the car has become a flying machine again and fuel economy has gone up a bit too!
I presume because now the turbo is doing what its supposed to do when its supposed to do it :)

Sorry for a repeated post but I saw two threads running on the same topic so I thought I would post this here also.

This product was recommended on the forum a few months ago.

http://www.turboclean.org/

Might be worth using if you're having turbo problems.

This could go in the articles section as a "How to fix" type post?

Worth following the mesh clean out first as they specify on the website before using the turbo clean:

"Check the vacuum box installed on the turbo is working properly, since the variable geometry is controlled by it."

But that stuff definately sounds interesting :)

Just been hunting in my tool box for the required tools to do this. I have everything except brake cleaner. Could you use wd40 or should I wait until tomorrow till I can pop to the local motorland to get some brake cleaner?