Screeching noise at start-up!

[crzycav86]

Hi. I have a 93 240sx with the KA engine...

Over the past week or so, a new annoyance has arisen. When the engine isn't warmed up, it makes an annoying screeching sound at start-up, and then it goes away after about 10 seconds. I've come to the conclusion that it's due to a lack of lubrication that exists before the oil pump gets the chance to bulid pressure. ...it's the same noise that I experienced briefly after doing a timing chain job in September.

Now for the questions: What exactly is the noise? Why is it doing it now? How can I stop it? What misfortunes will I suffer if I don't fix it soon?

Any help would be much appreciated.

Thank you.

[Prelude Guy]

I think it is one of your accessory belts, mainly the alternator belt. That's what my car was doing.

[crzycav86]

But why does it only do for 10 seconds at startup? Wouldn't it make the screeching noise all the time?

[benemorius]

Different things can cause different belts to squeal at different times. The power steering belt may only squeal while turning, the alternator belt may only squeal while it's under a heavy load, and the fan belt may only squeal while cold. The bottom line is - belts squeal if they're too loose, so check that all are properly tightened.

It could be something inside your engine also. Usually when someone says "screech" I think bearing (metal on metal), and when someone says "squeal" I think belt (rubber on metal), but it doesn't always happen that way. Hope that it's a belt. You don't want it to be a bearing...

[CDE]

But why does it only do for 10 seconds at startup? Wouldn't it make the screeching noise all the time?

The noise most likely occurs because the belt is cold and stiff and tend to slip in the pulley's. The friction warms the belt up pretty quick though and that's why it's only 10 seconds long. It's pretty cold where I live in the mornings and my 89 coupe squeels for a good minute or 2, just depending how cold it is. You could try tightening the accessory belt and be careful not to over-tighten it.
Modified by CDE at 2:41 PM 2/18/2005

[crzycav86]

Thanks guys. That's some good info.

I'll look into it tommorow.

[jacob360]

The alternator is under a heavy load immediately after startup because it has to recharge the battery after pumping out all those amps to run the starter.

Adjust your belt tension, but be careful not to over tighten it.