Coolant hose heat protector & change-over valve tube

[logray]

996 MY 99' C2 Manual US.

1.) Does anyone know what the change-over valve does? Do I need to worry if one of the tubes attached to it is broken? One of the tiny hard plastic tubes attached to the 996 605 123 01 (change-over valve) is split clean in half. There are two hoses going into the change-over valve. The change over valve (whatever that does) mounts pretty much directly above the alternator onto the intake manifold. I put some duct tape on the tube to hold the two halves together but doubtful it is doing much except keep the broken half of the tube from escaping into the engine bay. I have no idea where these tubes go, and am thinking it could be close to impossible to replace without dropping the motor. Anyhow, I thought it was interesting that the part these tiny hoses is listed in the catalog, but the hoses themselves are not as far as I can see. Any ideas what these hoses and change-over valve are for and/or have a part number? The tubes are way to small for an inline coupler. Any DIY suggestions? Should I worry one of the tubes is broken?

Here's a pic of the change-over valve.

2.) Over the left intake manifold there are a bunch of coolant hoses that are protected by a heat resistant wrap/blanket type thing that is supposed to velcro together. My heat protector wrap thingy is completely disintigrated. Does anyone know what the part number is or have a DIY suggestion? Heat resistant tape?

3.) There is another heat wrap that is completely gone for some more hoses directly in front of the left intake manifold. Can't find that part either. DIY suggestions are welcome.

Thanks in advance!

Edited March 24, 2009 by logray

[nghiaho58]

Try http://www.pelicanparts.com/. Their phone number is 1-888-280-7799.

They may have an answer fro your question.

Good luck!

[logray]

Try http://www.pelicanparts.com/. Their phone number is 1-888-280-7799.

Thanks. I do a lot of shopping on pelican. Also sunset. Ebay. Google. I guess what I'm looking for is some DIY and technical advice as to what some of these parts do, maybe I'll move this post to the general discussion. There is a small chance pelican support rep could find these parts, but they may not be able to tell me what they do. I'm guessing if the parts are not listed in the catalog, they won't be orderable.

[bmohr]

don't worry. I did the exact same thing when replacing my air and electric changeover valves. Just put a piece of tight tubing or better yet shrink wrap tubing over it and you will be good to go. Fking little black pieces of plastic strewn all throughout a hot *** engine = breakage:(

[logray]

don't worry. I did the exact same thing when replacing my air and electric changeover valves. Just put a piece of tight tubing or better yet shrink wrap tubing over it and you will be good to go. Fking little black pieces of plastic strewn all throughout a hot *** engine = breakage:(

I found the hose. It is number 19 in the pic above. There is not a part number from Porsche but it is a 420mm hose. It helps the change over valve controls the resonance flap. The changeover valve kicks in and closes the flap at certain RPMs by use of vacuum.

When I removed this hose it broke in another place. I tried to repair it with some heat shrink tube and electrical tape but it is only temporary. I will probably have to find a replacement hose with similar I.D. since Porsche does not sell a replacment. Unless I want to keep the flap closed or open all the time.

It connects to the back end of the intake manifold (middle rear tube) in the picture.

As for the heat protection I managed to tie wrap the old pieces to the hoses.

Edited March 27, 2009 by logray

[logray]

One thing I forgot. Does anyone know if I have to complete a drive cycle before the secondary change over valve/vacuum operates the resonance flap? After replacing AOS, clearing some CEL codes and having the battery disconnected for a while I have a lot of frowns in the DME check and OBD ready menus in PST2. I am thinking maybe I have to complete a drive cycle?

Edited March 27, 2009 by logray

[Loren]

There are people that say a PST2 can change them - but not in the US I think. They don't want a way around smog checks.

You will likely have to just drive the car until they have enough drive cycles to change the ready state to happy faces.

[bmohr]

hey logray, call up Oklahoma Foreign, tell them what piece you need and they will pull it from a wreaker from their salvage yard for dirt cheap. I get alot of parts from them. Speak to Gary or Matt.

http://www.oklahomaforeign.com/

[1999Porsche911]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

[logray]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

Thanks for the corrections. My posts are edited. I was reading through a ton of posts and apparently got a few things mixed up.

[996noob]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

I'm resurrecting this thread because I have not completely solved my problem with the vacuum lines.

Would someone help me out with the logic and see if I am interpretting this correctly?

The resonance Flap is normally open, which means that in rest state it is Open, which means that if there is no vacuum applied to the Flap, it is Open. Can I conclude that the Changeover Valve is closed?

Idle is between 700 to 3120rpm, during which Flap should be Open, which means that at Idle, Changeover Valve is closed. Can I conclude that there should be no vacuum if I pull off the side vacuum hose on the Changeover Valve?

I'm asking because ever since I broke those hoses, I've been having very uneven power delivery during WOT through the rev band.

And now that I have fixed the hoses (and connected them to the correct places), I still have the uneven WOT power.

Do I need to reset something?

Would buying a Durametric help me solve the problem I am experiencing?

Can I test if my changeover valve is working?

Edited July 25, 2009 by 996noob

[1999Porsche911]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

I'm resurrecting this thread because I have not completely solved my problem with the vacuum lines.

Would someone help me out with the logic and see if I am interpretting this correctly?

The resonance Flap is normally open, which means that in rest state it is Open, which means that if there is no vacuum applied to the Flap, it is Open. Can I conclude that the Changeover Valve is closed?

Idle is between 700 to 3120rpm, during which Flap should be Open, which means that at Idle, Changeover Valve is closed. Can I conclude that there should be no vacuum if I pull off the side vacuum hose on the Changeover Valve?

I'm asking because ever since I broke those hoses, I've been having very uneven power delivery during WOT through the rev band.

And now that I have fixed the hoses (and connected them to the correct places), I still have the uneven WOT power.

Do I need to reset something?

Would buying a Durametric help me solve the problem I am experiencing?

Can I test if my changeover valve is working?

No. Open is OPEN. That means the flap is open when vacuum is not applied. Or, to put it another way, the flap is closed when vacuum is applied. Removing the side vacuum line that goes to the flap should not find any vacuum when at idle or when engine is off.

Edited July 25, 2009 by 1999Porsche911

[996noob]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

I'm resurrecting this thread because I have not completely solved my problem with the vacuum lines.

Would someone help me out with the logic and see if I am interpretting this correctly?

The resonance Flap is normally open, which means that in rest state it is Open, which means that if there is no vacuum applied to the Flap, it is Open. Can I conclude that the Changeover Valve is closed?

Idle is between 700 to 3120rpm, during which Flap should be Open, which means that at Idle, Changeover Valve is closed. Can I conclude that there should be no vacuum if I pull off the side vacuum hose on the Changeover Valve?

I'm asking because ever since I broke those hoses, I've been having very uneven power delivery during WOT through the rev band.

And now that I have fixed the hoses (and connected them to the correct places), I still have the uneven WOT power.

Do I need to reset something?

Would buying a Durametric help me solve the problem I am experiencing?

Can I test if my changeover valve is working?

No. Open is OPEN. That means the flap is open when vacuum is not applied. Or, to put it another way, the flap is closed when vacuum is applied. Removing the side vacuum line that goes to the flap should not find any vacuum when at idle or when engine is off.

That's what I meant -

No Vacuum, Flap Open.

Vacuum, Flap Closed.

I wanted to further conlude if -

No Vacuum, Flap Open, Changeover Valve Closed.

Vacuum, Flap Closed, Changeover Valve Open.

so that I can diagnose the proper operation of my changeover valve.

Does a faulty changeover valve throw up any error codes?

[1999Porsche911]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

I'm resurrecting this thread because I have not completely solved my problem with the vacuum lines.

Would someone help me out with the logic and see if I am interpretting this correctly?

The resonance Flap is normally open, which means that in rest state it is Open, which means that if there is no vacuum applied to the Flap, it is Open. Can I conclude that the Changeover Valve is closed?

Idle is between 700 to 3120rpm, during which Flap should be Open, which means that at Idle, Changeover Valve is closed. Can I conclude that there should be no vacuum if I pull off the side vacuum hose on the Changeover Valve?

I'm asking because ever since I broke those hoses, I've been having very uneven power delivery during WOT through the rev band.

And now that I have fixed the hoses (and connected them to the correct places), I still have the uneven WOT power.

Do I need to reset something?

Would buying a Durametric help me solve the problem I am experiencing?

Can I test if my changeover valve is working?

No. Open is OPEN. That means the flap is open when vacuum is not applied. Or, to put it another way, the flap is closed when vacuum is applied. Removing the side vacuum line that goes to the flap should not find any vacuum when at idle or when engine is off.

That's what I meant -

No Vacuum, Flap Open.

Vacuum, Flap Closed.

I wanted to further conlude if -

No Vacuum, Flap Open, Changeover Valve Closed.

Vacuum, Flap Closed, Changeover Valve Open.

so that I can diagnose the proper operation of my changeover valve.

Does a faulty changeover valve throw up any error codes?

Changeover valve is normally closed meaning that without electric signal to it, no vacuum will get to the side nipple. An electrical problem with valve with throw a code. A vacuum leak will not unless it is large enough to make you run lean and then you will get an O2 sensor code.

[1999Porsche911]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

I'm resurrecting this thread because I have not completely solved my problem with the vacuum lines.

Would someone help me out with the logic and see if I am interpretting this correctly?

The resonance Flap is normally open, which means that in rest state it is Open, which means that if there is no vacuum applied to the Flap, it is Open. Can I conclude that the Changeover Valve is closed?

Idle is between 700 to 3120rpm, during which Flap should be Open, which means that at Idle, Changeover Valve is closed. Can I conclude that there should be no vacuum if I pull off the side vacuum hose on the Changeover Valve?

I'm asking because ever since I broke those hoses, I've been having very uneven power delivery during WOT through the rev band.

And now that I have fixed the hoses (and connected them to the correct places), I still have the uneven WOT power.

Do I need to reset something?

Would buying a Durametric help me solve the problem I am experiencing?

Can I test if my changeover valve is working?

No. Open is OPEN. That means the flap is open when vacuum is not applied. Or, to put it another way, the flap is closed when vacuum is applied. Removing the side vacuum line that goes to the flap should not find any vacuum when at idle or when engine is off.

That's what I meant -

No Vacuum, Flap Open.

Vacuum, Flap Closed.

I wanted to further conlude if -

No Vacuum, Flap Open, Changeover Valve Closed.

Vacuum, Flap Closed, Changeover Valve Open.

so that I can diagnose the proper operation of my changeover valve.

Does a faulty changeover valve throw up any error codes?

Changeover valve is normally closed meaning that without electric signal to it, no vacuum will get to the side nipple. An electrical problem with valve with throw a code. A vacuum leak will not unless it is large enough to make you run lean and then you will get an O2 sensor code.

[996noob]

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

I'm resurrecting this thread because I have not completely solved my problem with the vacuum lines.

Would someone help me out with the logic and see if I am interpretting this correctly?

The resonance Flap is normally open, which means that in rest state it is Open, which means that if there is no vacuum applied to the Flap, it is Open. Can I conclude that the Changeover Valve is closed?

Idle is between 700 to 3120rpm, during which Flap should be Open, which means that at Idle, Changeover Valve is closed. Can I conclude that there should be no vacuum if I pull off the side vacuum hose on the Changeover Valve?

I'm asking because ever since I broke those hoses, I've been having very uneven power delivery during WOT through the rev band.

And now that I have fixed the hoses (and connected them to the correct places), I still have the uneven WOT power.

Do I need to reset something?

Would buying a Durametric help me solve the problem I am experiencing?

Can I test if my changeover valve is working?

No. Open is OPEN. That means the flap is open when vacuum is not applied. Or, to put it another way, the flap is closed when vacuum is applied. Removing the side vacuum line that goes to the flap should not find any vacuum when at idle or when engine is off.

That's what I meant -

No Vacuum, Flap Open.

Vacuum, Flap Closed.

I wanted to further conlude if -

No Vacuum, Flap Open, Changeover Valve Closed.

Vacuum, Flap Closed, Changeover Valve Open.

so that I can diagnose the proper operation of my changeover valve.

Does a faulty changeover valve throw up any error codes?

Changeover valve is normally closed meaning that without electric signal to it, no vacuum will get to the side nipple. An electrical problem with valve with throw a code. A vacuum leak will not unless it is large enough to make you run lean and then you will get an O2 sensor code.

Thanks for the information and the clarifcation. I'm getting to know my car better everyday thanks to you guys.

Last question, I did try to suck on the Flap hose, and it did make a sound like it was flapping, but I have no idea if it flaps partially or fully. The amount of air needed to make the sound wasn't much. I keep feeling as though it should take more volume for a full swing, but I have no mental picture of how it works, so I can't judge properly.

Is the Flap ever known to fail, become stuck, move partially, or is it a part that in general never goes bad?

If there is really no way to tell unless i disassemble the intake, then I guess I will have to take it apart to check.

[1999Porsche911]

It would be extremely unlikely that flap only moves part way. You can verify full 90 degrees movement externally by looking at the pivot point visable on the tube while you apply vacuum. It should move 90 degrees.

Edited July 26, 2009 by 1999Porsche911