Scraping Rattle on Cold Start

[ivode]

Hello all. New owner of a beautiful 2018 GT2. I am working through all the small issues that come along with this vehicle (mostly rattles of some form). But I am stumped by a noise that is happening at cold startup. It ONLY happens on cold start and persists for about 15-30 seconds no matter if the vehicle is at idle or moving. I've looked through the forum and can't find something that appears to be a match.

Sounds starts about 9 seconds into the video and happens 4 times in a row. Any ideas on what this sound is?

 

[Snicklefritz]

more like 5-6 seconds into the video. it's just a cold startup noise peculiar to your vehicle. if it goes away. by the way, I don't move until the rpms drop after a half a minute or more. if that noise is gone by then don't worry about it. sounds a bit like your baby is purring a greeting. it's not exactly a creepy worrisome sound in my opinion.

 

[Kodiack]

It almost sounds like your dynamic headlights might be acting weird..sounds like a motor cog slipping or something.
Do you headlights align at startup?

 

[ivode]

The headlights seem to be operating alright. Good idea but since it is only on cold startup, that might not be the culprit.

 

[ivode]

more like 5-6 seconds into the video. it's just a cold startup noise peculiar to your vehicle. if it goes away. by the way, I don't move until the rpms drop after a half a minute or more. if that noise is gone by then don't worry about it. sounds a bit like your baby is purring a greeting. it's not exactly a creepy worrisome sound in my opinion.

It feels like something is grinding. I'm curious if anyone else has that sound. Hard to believe it is just the standard car warmup. I think Kia would get lots of complaints!

 

[Kodiack]

It almost sounds like plastic gears grinding in a sequence...I would try starting it under different conditions.
I would start with having the heater controls shut off and everything else that is accessory...try to narrow it down to mechanical from the engine itself.
Try putting it in accessory first for a couple of seconds before you start and see if it still does it.
That is not a normal starting sound...the HPFP is the only normal startup sound as far as I know.

 

[ivode]

I'll give that a shot Kodiak. It sounds like it is coming from the exhaust at the rear end of the vehicle. Agreed it sounds like grinding. Or perhaps a harsh "gurgle" akin to lots of water in the exhaust being spit out. But I've seen no evidence of condensate build up in the exhaust. And it would have to be a LOT for the noise.

I have tried accessory mode and can confirm the sound only happen after ignition.

 

[Kodiack]

Hmm....low pressure fuel pump maybe? Or possibly the fuel return line chattering..
Is the sound quieter with a full tank of fuel?
Just a thought....

 

[ivode]

Looks like its time to visit the local mechanic!

 

[Snowwhite]

almost sounds like the exhaust is hitting the bumper, or some other part of the car underneath.

 

[ivode]

almost sounds like the exhaust is hitting the bumper, or some other part of the car underneath.

I did check the exhaust system last night, and the only thing that I could find that was even slightly loose was one of the tips. I just tightened it down as much as I could so there’s no wobble between it and the exhaust pipe. I’ll give it a run around townafter the car cools off and see if it made a difference. Thanks for the suggestion.

 

[Snowwhite]

exhausts expand as they heat up, so check for interference while it's cold. check close to the differential, that's pretty tight down there. I think if it was hitting the bumper it'd be a duller noise.