DJ

Ran,

Could this sound be the normal contracting metal "clicking" sound from rapidly cooling metal? You know, all the metal bits in the car expand as they heat up, and then when you stop the car, it begins to cool, and the metal contracts, causing the 'click-click-click' sound? That's prety normal. Drive the car hard on a cool night, then park it in the garage, and you'll probably hear it.

Tito

I agree with DJ, I think the ticking noise on shutting down is the exhaust contracting. Tito.

mick

HN Looks like your question has been pretty well addressed but as a side comment I remember reading in Excellence several months ago a comment in their question and answer section about putting the car in neutral and shifting directly into first when pulling away. They cautioned that this was hard on the transmission and the correct way to do it was to shift down through the gears ending in first. I assume they meant to then leave the clutch engaged instead of shifting into neutral and back into first. I have to admit I have always left it in neutral and then shifted into first to take off and have never had any problems with my clutch or transmission, but they caution against it and I would think they know what they are talking about. I will be interested in other comments from other members.

hn

Yes, my question has been well addressed. Sorry, i had been too busy to write. Thank you everyone.

By the way, i always try to avoid shifting down to a too low of a gear. I only shift down to 1st when the car almost stop. Sometimes it was in the between of 2 gears and i just had to decide either to lug the engine (if not too much) or to rev it (with a light tap on the gas).

thx again.

[ 07-06-2001: Message edited by: hn ]

Flying Finn

I think it's better downshift (I always do it). I've heard that downshifting makes transmission last longer (better oil circulation inside the gearbox I think?).
Also letting the engine idle (for a long time thought), will eventually polish cylinders (bad thing). And if you do it right (give a little gas and don't slide the clutch) you don't hurt the clutch either.

Another thing (about idling): before you shut the engine, I think you should only let the engine idle about 30 sec. or so, that will even the temperature differences in the engine. Of course, if you have turbo engine, you MUST let the engine idle about minute or so, that will give turbo enough time to slow down (tourbo ca run 100 000 rpm and if you shut down the engine before it slows down, it will turn without oil circulation...).

Also, that ticking sound, if I understud correctly (what sound), that comes from the exhaust because when it's cooling, metal will change it's form and that makes the 'noise'.

Hopefully, this helps.

[ 07-06-2001: Message edited by: Flying Finn ]

Ran

I forgot to mention that my earlier post about idling for 2 minutes before switching off applies only to turbo cars at the end of a drive.

Jimmy

When the car is at a stop, does it make any difference if
1. I simply put the car in neutral or
2. I depress the clutch while the car is still in gear (1st)

Tim 95 993 Pasadena

Jimmy...If you have to sit at a light for any length of time, I would ease the transmission into neutral. I don't think it's a good policy to sit at a stop light with the transmission in 1st gear and the clutch pedal depressed. That would put extra loads and more wear and tear on the trans. Also, I never rest my heavy foot on the clutch pedal while driving etc.

Anir

Thanks for the help. Clearly, it seems like I should decrease my idling time. Like some folks mentioned, this is usually an issue on car wash days. Robin, I'll try to listen for the vacuum sound.

With respect to letting the turbos cool down for a minute or two before shutting off the engine, I thought this was only an issue after a hard run.

In many city commutes, the turbos see minimal use in my car, judged by the boost gauge. As I understand it, that's one of the basic benefits of a turbo - you have the boost when you need it, but not when you don't (as opposed to a supercharger). Reduces wear and tear, and improves gas mileage.

So, after a "normal" drive, I don't typically wait more than 15 seconds before shutting off the car. Of course, I understand that the cooling off period would be important after a DE event or hard street run.

Am I interpreting this issue correctly?

E. J. - 993 Alumni

Anir,

The only thing for me to say on this is from my old turbo days. Even though the turbos are showing little or no boost, the impeller is still spinning. Remember that (I think its still true) that a turbo has been determined to be the fastest moving man made object ever, some spinning in excess of 125,000 rpm. Now thats fast. That means that yours under full boost are probably spinning close to 100,000 under full boost. When no boost is showing on the gauge, they still have to be spinning otherwise the engine would get no air.

I might be wrong, but it is always better to be safe then sorry. In my case with my old car (an awd eclipse) I never let the turbo cool down since I really wanted a bigger turbo and that would hasten the demise of the smaller one.

Flying Finn

I'd say let it idle little longer (about minute), even though there's no boost when not riding hard, turbo turns much more that engine does (many cases 10xengine rpm) so it take little time to slow that down. Nothing to do with the temperature, but the fact that it still might turn (without oil) after engine is shut down.

Anir

EJ and Finn,

I never realized how fast the turbos spin. Amazing engineering.

I plan to adopt your sound advice.

Thanks!

tom97c4s

When you are slowing down is it OK to put the car in neutral without using the clutch?

DJ

Tom,

No, don't do that. On some transimissions that would be just fine, but don't do it to your Carrera. These transmissions can't be shifted without the clutch without doing some damage. I wouldn't do it.

Nol, 95 993 C4

Turbo Timers

My previous two "fun" cars were both Turbo charged: an 89 Toyota Supra mkIII and an 84 Ur-Quattro. I used to idle those cars one or two minutes before shutdown after any ride.

"Turbo Timers" are a popular mod with the Supra Turbo owners. This circuit keeps the cooling/lubrication circulation for the turbo going for 5 minutes (or more?) after shutdown and key removal. It effectively prevents running the the turbo down without oil, and it prevents "coking" of the limited volume of oil in the bearings by the heat sink effect of the hot turbo assembly. Audi made quite a few changes to the turbo cooling of the quattro's incvluding switching from oil to watercooled (or the other way around, not sure). But I do believe the later Audi Turbo cars have a turbo timer like facility factory fitted. How about the 993TT's?

Cheers, Nol