JonDBM

I live in a shared house. One of the cars is an old Porsche 911. The owner idles it for at least 15mins if not longer each morning prior to driving off. This is right outside my bedroom window and wakes me up. Rather than just rant and rave, if I can offer him a reason why he shouldn't do this, then I have a good chance of gettimg him to stop.

So, is there a mechanical reason why you shouldn't idle a Porsche 911 before driving it off when its cold. I know that Scoobies can suffer as a result, and my old Golf Mark 3 specifically told you not to do it in the manual.

Any info greatly received.
Thanks, Jon.

beemerboy

i quote:

Never "gun" a cold engine as rings, seals and bearings just won’t take it for long. Steady operation for about 30 seconds is best.

It is a good idea to turn the heater on full on 911 and 912 after starting to help on warm-up, too. It is a lousy idea to let the car sit and warm up before driving off, not only on a Porsche, but on any car. Just drive off slowly and run in first or second gear for several blocks, not exceeding about 3000 revs on 4-cylinder engines or 4000 rpm with 6-cylinders. This procedure will actually warm up the engine faster and be easier on the engine than running in place. It also uses less gas.

Print this out and give it to the ****
BB

davedipster

I thought that running a cold car on idle was very bad for it, somthing about the mixture being rich washing the oil off the bores. That was in the old days of chokes, but it must surely still apply.
It's better to drive off straight away to warm up the engine as quickly as poss without labouring or thrashing. I would have a word with the guy and try and blind him with science, he may then stop doing it if he thinks he's doing damage.

Dipster

Dapster

Also if you idle the car you will warm the engine up but not the transmission so when you see the temp guage in the normal zone and gun the car, the rest of it will still be cold and you'll be inflicting a load more wear.

MarkCSC

Beemerboy's quote can be found here
Plus even if the engine is up to temperature the rest of the car won't be gearbox, diffs etc

Doh, must read the whole thread before replying and saying what the person above me has just said


[Edited by Mark Champion - 12/10/2003 11:10:21 AM]

JonDBM

Thanks a lot guys.
Much appreciated.

Jon.

bobbyh

my 2p's

petrol washout of oil in the bore linings, only occurs if you turn the engine OFF before it has completed the warm up phase.

The extra fuel dumped into the chamber to aid the cold start will not burn completely, andthen run down the bores when you turn off.

leaving a cringeworthy metal on metal scenario next time you start.

i think 10mins or 10 miles should surfice.

brickboy

If its an aircooled one, the piston to cylinder clearance is quite wide. The rich cold-start mixture will reduce bore lubrication, causing accelerated wear.

The condensation build up in his exhaust / heat exchanger from long idling will also rot it out quicker (unless it's already a stainless steel item) which might be a strong argument too