Time to replace combination valve?
+ Reply to Thread
Results 1 to 12 of 12
  1. #1
    Neutral
    Join Date
    Jan 2004
    Location
    San Francisco, CA
    Posts
    51

    Time to replace combination valve?

    I think it's time for me to replace a combi valve before my air pump dies. It seems that I have exhaust coming out on the intake side of the combi valve. It's not much but placing my finger over the intake I can definitely feel pressure. There is also knocking sound coming from the combi valve at start up that goes away as soon as secondary air circuit shuts down. So, what do you think? Maybe I am just paranoid and some exhaust and knocking is normal.

  2. Remove Advertisements
    VW Passat Forum
    Advertisements
     

  3. #2
    Neutral
    Join Date
    Jan 2004
    Location
    San Francisco, CA
    Posts
    51
    bump

  4. #3
    1st Gear
    Join Date
    Nov 2003
    Posts
    198
    Let me know what you find. I have a "Ticking" noise that I can hear only when I accelorate after the engine has been sitting for a while. VW Guys tell me its an Exhaust leak. exhaust Guys tell me to take it to VW. Noise goes away after about 10-15 seconds. No Power Loss...Just strange noise.
    :???: :???:
    Russ

  5. #4
    Neutral
    Join Date
    Feb 2003
    Location
    Arlington VA US of A
    Posts
    40
    I am sort of in the same situation. I still have a CEL that's been on for about 6 mos for the secondary air system. Looking at the manual it is likely one or more of: the relay, air pump, combi valve or the vacuum lines.

    I have replaced most all of the smaller vacuum lines including the PIA one that runs from near the turbo, around the timing belt cover to the intake as a starting point.

    Are there any tips to help narrow the source of the problem down a bit??

    <partial hijack>

    <full bump>

    :weirdo:

  6. #5
    Neutral
    Join Date
    Jan 2004
    Location
    San Francisco, CA
    Posts
    51
    Checking airpump is easy. Get under the car and disconnect the hose going to the combi valve. Make sure car is cold, start and feel if pump is pumping air. I plan on taking off combi valve this weekend. Let you know how it goes. By the way, I've started looking at this because of the exhaust leak that I could not locate. It only shows under load and is coming from the engine compartment (light rumble at moderate speeds 2500rpms and up). The sound is similar to the sound I am getting at startup with the secondary air injection system on - hopefully replacing combi valve will fix it.

  7. #6
    1st Gear
    Join Date
    Jun 2001
    Posts
    454
    Anybody have pics of the combi valve? I hear a lot of talk about it lately but I ahven't seen any pics. I just replaced my PCV valves and I'm curious where the combi valve is.

  8. #7
    2nd Gear
    Join Date
    Jun 2000
    Location
    Springfield MA USA
    Posts
    697
    Quote Originally Posted by sneg
    I've started looking at this because of the exhaust leak that I could not locate. It only shows under load and is coming from the engine compartment (light rumble at moderate speeds 2500rpms and up).
    sneg, please keep me posted on this if you find it. I have been searching for a similar sound for 4 months with no success! :???:

  9. #8
    Neutral
    Join Date
    Jan 2004
    Location
    San Francisco, CA
    Posts
    51
    Thought I'd mention. I have a B5 2001 GLS with AUG engine and 46000 miles.

    vwfool2000: the combi valve is in the back of the engine. It is a round (about 2inch in diameter), silver thing that sits between engine and the firewall. Open up the hood you should easily see it.

  10. #9
    Neutral
    Join Date
    Jan 2004
    Location
    San Francisco, CA
    Posts
    51
    Well, I did replace the combi valve. Noise at the start up is much better. The exhaust leak, however, is still there. Will have to look further....

  11. #10
    1st Gear
    Join Date
    Nov 2003
    Posts
    198
    What does your "Exhaust Leak" sound like? Mine sounds like a Playing Card Stuck in a Bicycle tire. Just for about 10 Seconds and only under stress. Then it goes away..... :???: :???: :???: Is that what your sound is like?

  12. #11
    2nd Gear
    Join Date
    May 2000
    Location
    Pasadena, CA USA
    Posts
    790
    You can put a piece of white paper near the gaskets and see if you get any exhaust dirtying up the paper. Of course you only have like 2 minutes before most of the exhaust gets too hot to touch. Holding your hand works too, but sometimes you can put paper where you can't put your hand.

    sneg, the combi valve was not sealing well, so exhaust was leaking out the side connected to the air pump? Did you see any soot on that side? Someone said you should if its leaking.

    SalManilla, I've heard exhaust leaks that sounded sort of like a clarinet, with a vibrating reed, but that is a pretty serious exhaust leak, and the car sounded like crap in general. An exhaust leak tends to be pretty loud and deep, even a small one.

    -Ian

  13. #12
    Neutral
    Join Date
    Jan 2004
    Location
    San Francisco, CA
    Posts
    51
    swett, the intake side of the combi valve had some carbon build up. Whoever said that there should be soot was right. I think I've replaced combi valve before it totally failed, so the carbon layer was much lighter on the intake side compared to the side connected to the exhaust.

  14. Remove Advertisements
    VW Passat Forum
    Advertisements
     

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Powered by vBadvanced CMPS v4.1.2