Cold Start Scratching noise from engine
 

Dear series II owners, I have been struggling with this noise for a while, but it seems it is getting worse as the weather is becoming colder these days. I have tried the search, and I found a lot of threads talking about "sand in the box" and "marble in the glass" but not this kind of sound. I hope someone can point me in the right direction before I send it to the dealership.

I noticed this noise in June, which it did not present at the cold start in mornings. At the time, I could hear it from 3k-5k rpm and the noise was less noticeable when the engine was warm. Cleaned MAF sensor, checked there was no oil in the intake, the noise did not change. I thought it was the "sand in the box" sound until last week when I started it in the morning, which the outside temperature was below 60. I heard a loud scratching noise immediately after the car started, it noise lasted for about a second, but when I rev it to 3k, it came back. What possibly could this sound be from??? Pulley, belt, or something worse?

Here is a video I recorded:

Likely one of the belts. If they are more than 3 or 4 years old buy new ones...it is worth the peace of mind.

Could be the idler pulley as well..... when you replace the belts turn the pulley and see if it turns smoothly. If it is grinding or hard to turn you should replace that as well. If you are a DIY guy he bearings are a common size and not the difficult to replace.

Check the alternator at the same time....same thing should turn smoothly and not grind

I took off both belts and spun the pulleys yesterday, no cracks were found on the belts and pulleys can be turned freely. Could this noise come from a bad A/C compressor?

Are you sure it's not the air pump? It typically only runs during cold startup to help warm up the cat converter quicker. Common problem for the air pump bearings to go bad and screech. I couldn't really hear anything in the video with all the other bells & whistles going off

I'm not 100% sure, but I believe this noise turns into a whining noise at 3k rpm and dies off at 5k, regardless of the engine temp. It's more obvious when the engine is cold though. The noise happens at around 9sec mark in the video. The closest description would be a metallic scratching noise, sounds like a jammed gun. Does air pump operate when the engine is warm?

No, well good luck

Easy to rule out the air pump. Just disconnect the connector at the pump and see if the noise goes away

I decided to change the belts anyway, called the dealer nearby and checked online, the A/C belt for series II is on back order, dealer said nobody has it in the U.S., and there's no ETA. I am wondering if we could use series I A/C belt? I know the part # is different, but I'm not sure if they are same in length though?

You could always try RockAuto

Just checked and bought one manufactured by Gates, thanks a lot!

Changed both belts today with a new idler pulley, noise is still there. Checked under the hood, it seemed the noise is mainly from where the alternator is. I'm considering changing the alternator, but should I drive until it throws a code?

Also took another video, ran from idle to around 3k rpm and then 5k. The noise is not very distinctive with other sounds from the engine, does it sound like a bad bearing in the alternator?

I must just be a deaf old guy :dunno:

lol, that one was bad, just recorded a new one today:

It it the short noise right after it starts?

That sounds like the starter drive is slow to disengage and is dragging

My Accord actually had a dragging starter(common problem, too). Doesn't sound like that. A dragging starter tends to have a constant noise for a short while, not intermittent.

OP also said it turns into a whine at higher RPM, so it wouldn't be the starter.

If it activates at a certain RPM range, could it be a valve in the intake system? Valves like SSV engage/disengage at certain RPM. Just a thought.

It is the short noise after it starts, but I do believe it turns into the sound when I rev it up at 32''. There are few other symptoms: 1. The noise after it starts does not happen when the engine is warm. 2. Initially, when the engine is not completely warm, the scratching noise happens at 3k rpm, as the engine becomes warmer, the noise is less obvious at 3k but 4k rpm. 3. The noise is gone after 5k rpm and I have not felt any power loss.

Turn the stereo volume up ...

Let's try to localize it. Can't do that with a video, but if you think it's the alternator, start there. Get a wooden stick, put one end on the suspected source of the noise, the other end to your ear and have someone turn the car on or do whatever they need to do to make the sound happen. If the source is whatever the stick is touching, you'll hear the sound loudly through the stick. If it's not, you'll hear it through the air. Poke at a few parts, you should be able to narrow down what it isn't, if not what it is.

You can always take the alternator belt off as well.....just don't let it run very long

Put a stick on the alternator today but no odd noise, so I think it might be the starter, is it possible for the starter to grind after the car is started and running at certain rpm?

Usually it is very short lived right after the engine starts. If the solenoid didn't disengage the drive it would scream bloody hell very shortly because of how fast it would be going.

You could have 2 issues at the same time.....although I usually don't tell people to think that way...it can happen :)

Put a stick to the starter ;) ;)
Put a stick on everything until you find the culprit.

OK, I am a bit like Mark, perhaps it is old age..

All I could hear in Vid 1 is high beeps and high squeaks like a printer, I have none of these sounds in my S2, has yours got AKE, advance key-less entry?...

the second under bonnet/hood I could hear nothing wrong, too noisy, normal Rotary RPM rev.

3rd vid I hear some squeaks and yes it could be starter overrun/solenoid, is yours a turn flip key or turn a knob (AKE), IF that turn knob has a slow turn around (spring) your starter may be still engaged, but as Dan said usually they will scream, personally your starter seems just a little slow or weak for a S2, could be Battery condition/charge maybe.

But agree high pitched is also usually Air Pump bearings, but they will usually scream all the time until turn off, about 90 seconds after first start on cold engine.

First I thought Starter in 3rd vid start up, but then at vid end another noise before vid goes off, just throwing this out any loose exhaust manifold heat shield, brackets.

I have the AKE, but the turn knob spring doesn't appear to be bad. The previous owner put a new battery in but I forgot when so I need to check on that, how often does the 8 require a new battery?

Not any more often than any other car. 5 years? 6? 10?

Batteries don't make noises and your startup sounds fine. Guessing is the long way to do this, eliminate one system at a time.