Strange cold startup noise

[bobo83]

My MR2 has been making a strange noise on cold startups these past few months. I could describe it as grinding noise or whooshing noise, hard to say. It only lasts for a few seconds, happens on the first start of the day and only on 80% of the days.

Here is a video compilation of the noise: youtube video. The first two examples are the bad cold starts and the last one is a normal start.

I believed that the vacuum leak that I have recently fixed was the cause for this ... but it was not.

If my memory serves me right, I started to have this noise after I changed the exhaust and replaced the timing chain tensioner. I recently reverted the exhaust change and the noise is still there. Could it be the tensioner ? It's a brand new Toyota one, and I did make sure it clicked after I installed it. I had the car only for a week before making these changes so maybe this weird sound was always there, who knows.

Does anyone have any idea what this noise could be ?
Thanks.

[Gaz mr-s]

Does it actually sound worse/more metallic to the ear, than the recording of it?

[Zxrob]

My initial thoughts are is sounds like a bit of camchain "slap"

Perhaps worth while getting the tensioner out, checking and re-setting.

Rob

[bobo83]

Does it actually sound worse/more metallic to the ear, than the recording of it?

I would say it's quite loud. It's definitely a metallic sound.

My initial thoughts are is sounds like a bit of camchain "slap"

I thought the same. But it does not happen when the engine is warm, and even then, my impression is that in only happens on cold days. It's very strange.

I got a stethoscope recently and will try to pinpoint the exact location.

[Gaz mr-s]

It might be the starter motor bendix.  It's a rather unpleasant grating sound. Sometimes it's caused by lack of use, - how much has your car been used lately.?

This may not prove anything, - try starting, if it makes the noise, turn it off.  Repeat, if it doesn't chances are that's what it is.  If it does, repeat again.  If it doesn't do it before any heat is in the engine, that'd point away from the engine, I'd think.

[Beachbum957]

We chased a very similar sound for quite some time (months)  It was a broken weld on the heat shield in the Y pipe on the main cat.  Once the pipe got even a little warm, no noise. We had this happen on 2 different main cats.

[Joesson]

We chased a very similar sound for quite some time (months)  It was a broken weld on the heat shield in the Y pipe on the main cat.  Once the pipe got even a little warm, no noise. We had this happen on 2 different main cats.

On here, at one time, that was a recurring problem/ question. A rattle at start up, almost always, as you say a broken weld on the Y pipe below the three amigos ( the three fixings holding the bottom of the manifold to the start of the cat.
I fixed mine some years ago and no recurrence.

[mr9]

I've got a similar noise on my car after I installed the turbo.

I'm assumed it was something wrong with that exhaust and have been ignoring it

[bobo83]

I believe it is not the exhaust as the car has had two different exhausts systems, including the manifold, and it still does the noise.

It might be the starter motor bendix.  It's a rather unpleasant grating sound. Sometimes it's caused by lack of use, - how much has your car been used lately.?

I found online some videos with noises like mine and indeed sometimes the problem was the starter motor. I am using the car daily so it's not lack of use causing it.

Will try to use a stethoscope on the starter motor but it's a bit tricky to get to it (without getting underneath the car).