Geldgrube

AOS (air / oil separator) can cause the smoking at startup.....

With the engine idling, try removing your oil fill cap - if its difficult to remove (because of a vacuum) then there is a good chance your AOS has failed.

If it has failed, your throttle body will be oily and need cleaning too

Steve,

It's certainly worth checking but wouldn't smoke appear from both tailpipes if the AOS was faulty?

Thanks. What's the prognosis if it is sooty or oily?

Well, if it's just one plug that's oily, I would guess either leaking valve seals or an oil ring on that cylinder. If it's sooty, I would check the injection system (maybe the injector on that cylinder?). Assessing the plugs gives you a pretty good indicator of what's going on when you have one tailpipe a different colour than the other. Right now, we know there's something going on with the right bank and checking the plugs on that side would narrow it down even further.

When you say it "coughs" around 3000 rpm, are you mistaking that for the variocam kicking in (it changes around 3100 rpm) or did it just start "coughing" at the same time you noticed the smoke from the left tailpipe?

Thanks for your help, my answers are in CAPS below your questions:

1. So, you're down about 2/3 quart of oil since December. How many miles have you driven in that time?

1,500 miles TOPS. I HAVE 5 MILES EACH WAY TO WORK 5 DAYS A WEEK, LONG-ISH RUN ON THE WEEKENDS, ALSO TRAVEL A BIT FOR WORK SO IT'S GARAGED THOSE TIMES.

2. When did you first notice the problem?

JANUARY, BUT IT'S GETTING WORSE. AT FIRST IT WAS A PUFF OF SMOKE, NOW IT CONTINUES UNTIL THE ENGINE IS WARM.

3. The left exhaust pipe is "coated in soot" but the right is not, correct?

CORRECT.

4. Are you hearing any unusual noises when you start the car or after the car is fully warmed up?

TAPPETS LIKE TICKING SOUNDS

5. Have you noticed any loss of power?

NOPE, BUT IT DOES SEEM TO COUGH INTERMITTENTLY AT 3,000 REVS WHEN ACCELERATING

6. What year car is this and what's the mileage?

2003 996 C4 CAB, 57,500 MILES. DECEMBER HAD THE 60,000 SERVICE DONE

7. Have you had any work done on the engine?

THE KNOCK SENSOR, 60,000 SERVICE, COILS & PLUGS AND CLUTCH HAVE ALL BEEN DONE IN THE LAST YEAR - TWO OIL CHANGESIN 2010 - MARCH AND DECEMBER. DO 5,000 MILES PER YEAR..

Well, the oil consumption is within spec (according to Porsche anyways).

Does the ticking noise go away after the engine is warmed up or is it always there?

I really think you need to pull a couple of plugs from the right bank (passenger side)....I would be looking at the #6 plug closely to see if it's oil fouled or black/sooty compared to #5.

Yes, the left tail pipe is coated in soot, though I can't say if the smoke is blue, it is grey and white. It continues until the engine is warm. The right tail pipe puts out very light exhaust, which I can describe with confidence as condensation.

Thanks, I will check the pkugs. When I had the plugs and coils changed June of last year #6 was heavily coated in soot. I also noticed crank over can be labored sometimes recently and easy others. Any thoughts would be helpful.

1. So, you're down about 2/3 quart of oil since December. How many miles have you driven in that time?

2. When did you first notice the problem?

3. The left exhaust pipe is "coated in soot" but the right is not, correct?

4. Are you hearing any unusual noises when you start the car or after the car is fully warmed up?

5. Have you noticed any loss of power?

6. What year car is this and what's the mileage?

7. Have you had any work done on the engine?

I suspect it's related to the cylinder bank. What am I looking at if this is the issue?

Is it blue smoke?

Is your left tail pipe coated in black soot?

How many miles have you driven since your last oil change in December?

Suggest that you check cylinder #6 and #5 plugs and report back (getting to those plugs is dead easy).

Ron

The work is now done. And the car runs beautifully. It cost about 4 grand in parts which included a new flywheel and clutch for about 2 grand. The other parts included a new RMS bearing and IMS upgrade, although the old one were fine it was done as a precaution as they are know to fail, an oil evaporator-separator as the diaphragm as beginning to leak which causes oil to leak and burn through the exhaust, ignition coils as they were cracked, spark plugs, camshaft brake sets, finally two valves along with parts such guides, lifters, seals, gaskets and fluids.

This took 50 hours in labor but it included 7 hours to remove 5 broken exhaust header bolts, along with removing the transmission and engine, removing the heads and rebuilding them, de-coking the pistons and heads and re-seating the valves, checking everything and replacing parts as needed (see above), replace flywheel and clutch bolts as incorrect bolts were previously fitted (the clutch had been replaced before but not at a Porsche dealer) and finally putting everything back.

I am glad I took it to Mark Motors in Ottawa as they were very professional. The work includes a two year warranty on parts and one year on labor. Thanks again Terry for all the work.

Oh, btw in the garage was another engine that had been sitting on a cradle ever since I brought my car in. I was told that it had more serious problem than mine and that the owner had first taken it to another place for repairs but they couldn't get it going again after spending thousands trying to repair it. Terry was going to tackle it next.

So, did the 50 hours of labour include dropping the engine, removing the heads, doing all the work you described and then re-installing the engine? It sounds like you dropped in excess of $10k on this rebuild.

Regards,

Ron

hello (i have already tried search function and looked through TSBs)

I have 2003 996 C4S with rear Summer wheels 11Jx18 45mm ET. Manual recommends rear 10Jx18 47 ET for winter tires. I have found a set of Porsche rims which are 10Jx18 but 65 mm ET. TSB says nothing about spacers on winter tires. does anyone know for sure if i can use 65ET with 18mm or 17mm spacers to get down to 47-48 ET. is it allowed by Porsche?

thanks in advance

I have the same car and the same winter wheels and have used 17mm spacers on the rear wheels for the last 3 winters with no problems. Don't forget that you'll need longer bolts though!

Cheers,

Ron

Interesting...that's something I've never considered. Given that I've replaced both seals, I'm wondering whether that's the root cause of my problem. How can I determine whether the bleeder is working properly?

Thanks

Hi all. I'm having problems with my front differential again on my 2003 C4S.

At 50k kilometers, I replaced the right carrier bearing (the bearing for the flange connecting the half-shaft). At 80k, I replaced the left side. I'm at 110k now and it looks like the left side is gone AGAIN....it's leaking as well. My Indy says that there's likely a problem with the way in which the bearing is fitting into the diff housing so replacing the bearing again won't help. He was actually quite surpised because he hasn't seen a lot of AWD probelms on the C4 or the turbos. Anyone out there have similar issues and more importantly, do you know where I can get a used diff at a reasonable price (I'm checking the usual parts places like Oklahoma, German Auto and, as a last resort L.A. Dismantlers).

Thanks, Ron

I will use 8" tall ramps for changing the oil in my 3.4 liter 996.

Since the car will not be level, it will not be possible to drain all the oil. When I put the new oil in, again I will not be able to gauge the oil level with the dipstick for the same reason.

I am concerned about overfilling and I am also concerned about not putting enough oil in, since I will need to start the engine to get the car off the ramps.

Does any reader have any information on the undrained quantity of oil, when using ramps for an oil change, or, in other words, how much oil should I put in the engine before I drive off the ramps instead of the normal 8-3/4, 9 quarts used for car level oil change?

Many thanks

Why don't you just measure the amount of oil you drain from the car and then add the same amount back in?

Nobody makes a 295 30 18 snow tire. The problem is its too wide. I posted to let others who may be interested in a snow what should work on standard wheels. Two wheel drive Carrera's are no problem because the front wheels can operate at different revolutions per mile. The all wheel drive cars need to operate at virtually the same revolutions per mile. The sizes I posted will fit on the standard wheel sizes and RPM will match. :)

Hi,

I have a 2003 C4S and use 225/40/18 and 265/35/18 winter tires on stock rims (8" front, 10" rear as recommended by Porsche for winter tires) . I used Pirelli's for the last two years and just recently purchased some LM25 Blizzaks from TireRack for this year. They're being discontinued and TireRack is clearing them out....I got them for 1/2 price.

Cheers,

Ron

I suggest you remove the belt and see if any pulleys wobble when spun. Even an idler pulley can do major damage if it breaks while running.

That's good advice from Loren. I recently had the same problem.....removed the belt and found one of the idler pulleys to be running rougher than the others (it's VERY easy to tell simply by spinning it by hand and listening). Cheap fix.

Good luck, Ron

They are available for free download here...

http://www.cannell.co.uk/Manuals.htm

As stated before here - those "free" manuals are not up to date and missing most of the 99 supplements.

As Loren stated those "free" or almost free manuals on the internet are the earliest versions from 1999 and have no updates, perhaps only one year wiring diagrams and do not include the OBDII manuals, Diagnostic manuals, or any information on the 3.6 L engine and on and on.

If one is interested in workshop manuals please PM me and I would be happy to assist you.

Thank you

Thank you for all input. Just purchased from Porschelibrarian. An easy transaction and well worth it to any 996 ownwer IMHO.

Doug Davis

I too just purchased a set from Porschelibrarian and I'm especially impressed with the quality of these manuals. The wiring diagrams are the best I've ever seen! You won't be disappointed with these manuals!

Cheers,

Ron

Those look like rca cables. Should be able to get those in any Radio Shack.

Paul

Sorry, I should clarify. I need the little adapter box that's in the picture...it connects to the AUX IN port of the Gateway 500 so that you can connect any audio device using RCA cables.

Hi all,

I picked up a used Dension Gateway 500 on Ebay but it didn't come with an AUX IN cable. Does anyone have one that they're not using with their unit? Here's what I'm looking for:

I've tried Eric at BumperPlugs but he doesn't sell the cable separately and I haven't been able to get a response out of Dension.

I'll make it worth your while ($$$$) :lol:

Thanks,

Ron

I had a similar noise on my 2003 C4S and it turned out to be the right carrier bearing on the front differential. The way I isolated it was to put the car on lift, start it up and put it in gear. I then held the right front wheel to stop it from turning; this eliminated the wheel bearing, brakes and CV-joint. I did the same for the left wheel to eliminate that side. The only thing left was the differential and when I tore it apart, sure enough, the carrier bearing was bad on the right side. I replaced the one on the left side as well. Total cost for parts was $98 including seals.

Good luck,

Ron

P.S. Out of interest, I called my local Porsche dealer to cost out the parts but they don't sell the bearings separately.....but they will sell you a new differential for $3,100!

Ron, thanks for this post!

Do you have the part numbers for the carrier bearing? Was it difficult?

Please let me know and thanks in advance!

I didn't take down the part numbers (there are two different bearings) but the numbers are stamped on the bearings and they are very common that are available through any parts supplier. The job itself wasn't difficult, it just takes some time to get the front diff off the car. Once it's off, it's dead easy to get to the bearings. Good luck!

I had a similar noise on my 2003 C4S and it turned out to be the right carrier bearing on the front differential. The way I isolated it was to put the car on lift, start it up and put it in gear. I then held the right front wheel to stop it from turning; this eliminated the wheel bearing, brakes and CV-joint. I did the same for the left wheel to eliminate that side. The only thing left was the differential and when I tore it apart, sure enough, the carrier bearing was bad on the right side. I replaced the one on the left side as well. Total cost for parts was $98 including seals.

Good luck,

Ron

P.S. Out of interest, I called my local Porsche dealer to cost out the parts but they don't sell the bearings separately.....but they will sell you a new differential for $3,100!

I have purchased one of these kits, but have been waiting to put it in because of the same concerns which you have. Help someone, Please. Ed

What does the "kit" consist of? Can you provide some details so that we can help?

Hello all,

I've just taken delivery of an '03 C4S and I'm trying to fill in some gaps in its service history. I tried getting a service history printout from the local dealer but they claimed that they couldn't release that info "due to privacy reasons".....whatever.

Has anyone else had any luck getting this info from Porsche?

Thanks,

Ron

p.s. great forum by the way.....seems like a very knowledgable, helpful group! :)