Engine noise - better when cold?

[Jonny042]

Hello all,

My car is a 1987 Carrera Coupe with the original 3.2, the car is new to me so I am unsure of what it should actually sound like.

When the car is cold it sounds MUCH better than when hot. It also seems to be more responsive and smooth at lower RPMS, say 1/4throttle and 3k rpm

In addition to this the noise it makes does not seem to be valves, sounds more like chains to me..... kind of clackity.

is it common for the timing chains to stretch/wear or get loose and noisy over time?

Is it possible that the higher oil pressure when cold and the extra pressure on the tensioners is keeping the noise down until it is warmer? Could this also be affecting cam timing?

Thanks and regards,

Jon

[yelcab1]

I noticed that too in my SC. I never did figure out why. The 3.2 has more bottom end torque so it is natural to be more responsive at the low RPM

[daepp]

My 72w/MFI sounds way better when cold. I am talking sound quality only - nothing to do with performance or anything other than they way I like it to sound. It almost sounds like there's less muffler when it's cold. Someone once told me it's due to the fact that air/oil cooled motors have plenty of expansion built into their metallurgy and fittings so they sound a little "loose" (?) when cold. Whatever it is, I love it!

[Jonny042]

Originally Posted by DAEpperson

My 72w/MFI sounds way better when cold. I am talking sound quality only - nothing to do with performance or anything other than they way I like it to sound. It almost sounds like there's less muffler when it's cold. Someone once told me it's due to the fact that air/oil cooled motors have plenty of expansion built into their metallurgy and fittings so they sound a little "loose" (?) when cold. Whatever it is, I love it!

Hmmm....... mine sounds "tight" when cold, with the most prevalent sound being the fan (which I like), and "loose" when hot. When it's hot the fan sound seems to be masked by a whole bunch of clattering and ticking sounds "thrashy" for lack of a better word.

I found my automotive stethoscope, going to give it a check tonight.

[Jonny042]

So I got my stethoscope out and poked around. Very interesting. You can go and listen to all 6 cylinders, and I bet if you listened long enough you would be able to pick out each valve on each cylinder.

All 6 cylinders sound about the same, tick tick tick but no tock tock..... so pretty good.

I also checked the cam chain covers left and right, nothing to unusual although I think I may detect a inconsistant rattle there..... which concerns me. Time to do a little more research using google advanced search.

Last but not least I was suprised by the amount of noise coming from the fan/alt area, so my next task when I feel like it will be to take off the belt and check all that out.

[wildcat077]

Jon,

My 89 sounds scary at times too when hot,especially when i'm idling at a red light,sometimes i feel it sounds like a dryer with a load of clothes tumbling around ... lol
Nice and tight when cold though !

Cheers !
Phil

[Drisump]

911's are not known as quiet cars. Warm Idle sounds a bit like a racket, with all the various bits doing their job, cold idle has more oil pressure and due to thicker viscosity, more oil in the various spaces in the engine. Hopefully your concern is just being a new parent. As far as power, the 3.2 has good low end grunt (torque) but the engine really starts to impress ABOVE 3000rpm. All of those independent clackety "bits" doing their job at wam idle, become a Porsche symphony. Makes me smile just thinking about it. Cheers

[Paulporsche]

My engine sounds more raspy and metallic when cold. When warm, it's mellower and seems to be quiter.