1999Porsche911

All good replays and not that stock belt is not sufficiant I ended up going with a gatorbelt provides better grip.

I also run Gator for that reason.

Verify that you have the correct belt size and all 6 ribs are on the pullies.

Check for broken oil pressure spring on the oil pump. Don't do anything drastic like changing the oil pump until you get a real mechanical oil pressure test.

Verify that both raditor fans are on HIGH speed when AC is running. Not running on high speed will quickly raise the engine temps to those levels.

The description is exactly what I experienced years ago in AR in August in our 99 C2. I quickly discovered that one of the front radiator fans was not working and drove all the way home to Seattle with the A/C working and the engine NOT overheating.

The secret...

Turn the temperature control to MAXIMUM cooling "lo", recirculate mode, and then use the blower speed to control/regulate cabin temperature.

Bypassing the system's reheat/remix temperature regulation path results in lowering the heat loading of the radiator enough that I did not need to replace the fan until I got home.

Actually, it was your high speed driving and therefore full air flow over the condensers that kept temps down. My fans are always completely off running on the highway and AC running while maintaining <200F engine temps. Just short trips, like from Chicago to Vegas, :notworthy:

Disconnect the negative cable from the battery for a few seconds and reconnect. Code is gone. Make sure you have your radio code.

Verify that both raditor fans are on HIGH speed when AC is running. Not running on high speed will quickly raise the engine temps to those levels.

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.

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.

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.

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.

If you have a noise up front and the fans are not activated and you are not moving, there is nothing else to cause the noise but a restriction in the radiators or front coolant lines.

Chances are one of your fan's bearings is bad. Fan can run normal for a long time with a bad bearing if you can stand the annoying squeal.

Someone in another thread mentioned examining his tires using a pyrometer. In my like of work, I have access to an infra-red gun type pyrometer. Is this good enough? I'm thinking after driving around for a while (what is a while?) and then checking across the face of the tire. I'm thinking I might be able to spot one area of the tire hotter than another, maybe suggesting a change in the camber or toe.

I see when watching races on TV that technicians press something directly on the tire to get its temp. I won't have access to one of those.

I ask about the pyrometer because by the time I would notice abnormal tire wear, a rather significant chunk of the tire would already be lost. [No?]

White: I'm not a show-off (he-heh). So no burnouts with the tires or drifting, etc. Mostly daily driving with occasional fun rides in some nearby mountain twisties. I'm putting on a new set of Kumho Ectsa SPTs after seeing them them workout very well on my 986 and consulting a recent thread here about them for a 996TT (most users were of the same experience as me with them, though one user felt they were not good).

1999: I'm not after 100% grip and so I will look into your advice re: going towards the min camber allowable by Porsche. By min toe, do you mean "as close to zero as possible" [i.e as "straight-ahead as possible"]? Related, what sort of loss in handling could I see with this? My 986 is nimble and handles great; excellent feel of the road. I wouldn't want to end up with a "vague" handling car.

You'll notice no less control with aggressive street driving.

Tire wear is extremely sensitve to alignment. If your camber is set to the maximum Porsche spec, you can go through a set of rear tires on the street in as little as 7,000 miles. Reduce the camber just 20% and you'll get another 4,000+ out of them. Those who get 20,000 miles out of their rears have their camber and toe set close to the minimum spec.

As with all things in life, you have to compromise. You cannot have both maximum handling ability and maximum tire life. For most drivers, dialing down the alignment is both safe and desirable.

From my username, many would know that I'm a current 986 owner, but I'm also a new member of the 996TT club(!)

The 996TT I'm getting has new but oddly worn rear tires. After less that 4000 mi, the rear tires are excessively worn on the outer side of the tread but near new on the inside. As a Boxster owner, I find this odd because Boxster owners normally see wear the other way around (inside worn first due to negative camber of the rear wheels).

Is this outer wear normal for a 996TT?

The dealer has aligned the 996TT's wheels twice in the past 2 years with the new tires coming in between the alignments. The 2nd alignment was just earlier this year and I can't see it having destroyed the tires so badly. Part of me thinks that the 1st of the recent alignments was perhaps bad.

I am replacing the oddly worn rear tires when I take over the car. I am worried about future tire wear in the 996TT and ruining the new tires right away like the previous owner has.

Related, I'd like to also ask: is the standard wheel alignment harsh on the rear tires in pursuit of maximum handling? If so, is there a modified alignment setup one can choose to extend tire life at the expense of some of that optimal handling? And if there is such a modified alignment, what sort of degradation in handling should I watch out for?

Did you get a printout of the alignment? Sounds like they dialed in positive camber rather than negative. Any alignment shop can quickly identify whether your camber is positive. If it is, rapid acceleration will make the outside half of the tires wear even more.

If you bought the car and the tires were already worn on the outside, maybe the previous owner remounted the tires to the wheels.

When I first changed mine I used the Mobil. Next day I changed it to the Shell and it was night and day.

Remove the entire strip that holds both covers. Lift the end of the strip from the front windshield and lift up carefully. There are clips that hold the strip down which will release quite easily when strip is pulled up. Then reseat the cover properly and put the strip back on.

Let me clarify:

So I was thinking of changing my Gear box oil, my 996 6SP has 73000miles nearly on the clock,…But I have been told by my indy to wait because Gear box oil change's it can sometime's cause problems?

If I drove an automatic 90,000 miles with original fluid,…

We’re not talking about an automatic. His indy told him - well, read it - that's what I am saying is Bull.

You can change gear oil at any time and mileage and it will all be good.

What problems would fresh fluid cause? IMO, that's Bull. I've heard this wives' tale before, but mostly regarding automatic transmissions.

Factory interval is 90k. For my own peace of mind, I cut that in half. Use the factory fluid.

If I drove an automatic 90,000 miles with original fluid, I would either not chenage it, or if compelled to do so, only change out about halpf of it at a time and the other half only after another 6 months or so if I find there has been no negative effects of the first change.

If you think its BULL, then go and change it all and the filter. IME, you have about a 50/50 chance that your transmission will not function as designed.

easy question for someone (other than me, anyway . . .) Is cylinder 6 on the driver's side or the passenger side. thanks!

Passenger side.

Speaking of the Durametric software, I was told it does not show ignotion timing. Is that true?

1999Porsche911,

How do you manually turn on the engine compartment fan?

Thanks!

Radiator Fan and Engine Compartment Fan Switch Mod

The 3.4 996 runs extremely hot when driving around town in temperatures higher than 75 degrees. This mod is a way to reduce coolant temps back to a safer level, helping to reduce oil temps and improving performance.

The mod consists of installing a switch that will allow you to turn on the high speed radiator fans at any time, while maintaining the automatic operation of the fans. We do the same for the engine compartment fan.

Radiator Fans

Connect a wire to the ground (Pin #85) of the 2 high speed fan relays located on the relay carrier located in the driver’s side foot well. The relays are #20 and #22. Feed this wire to where your switch will be located. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and then connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on both radiator fans providing maximum cooling. When you turn the key off, the fans will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off.

Engine Compartment Fan

Connect a wire to the ground of the relay located in the relay carrier behind the passenger seat, driver’s side. Relay #8. . Feed this wire to where your switch will be located. I simply fed the wire along the driver’s side of the car and under the door sill. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on the fan drawing air into the engine compartment. When you turn the key off, the fan will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off. This mod helps keep the engine compartment much cooler when driving around town and is particularly beneficial to any engine that draws its intake air from inside the engine compartment, such as the EVO SC.

If you are adventurous, you can automate the operation of these switches so they will switch off at a specific speed, or operate when vacuum is present only, etc. You can choose any style switch you want and even use Porsche switches. I simply used 2 toggle switches that I installed in the batwing,

Jim

Also, pull slightly on the emergency brake and see if the noise changes. . It could be a lose shoe.

Air is going to take the path of least resistance and if you do not have the bumper openings properly sealed with the ducts or other method, little air is going to pass through radiators. I would install the proper ducts as well as run the fans on high to draw more air into the radiators.

Air flow to the engine compartment is also important. The more flow you have, the cooler your car will run and the cooler your intake temperatures will be, giving you more power. You can manually turn on the engine compartment fan to assist in increasing the airflow.

Pick up 3 liters of Shell Transaxle Lube from the dealer for around $90.