[sabino56]

Hi. This is one of those impossible questions but I'm stuck and looking for ideas.

Car idles smooth and drives great, no problems. On cold start, idle ~800ish and after warming up drops to ~600ish. When rpm drops a knock/low rattle sound starts.

When the noise starts I can see the tension pulley start to bounce very slightly like something is causing problems. However, with belt off every thing feels ok to me by hand - all spin smoothly, no shaft play. If I leave belt off, no noise.

Sound occurs with and without A/C on - but I think the compressor is always rotating on these models so I don't think it rules out A/C.

I was just hoping this is something someone has also had a problem and found something - even if unlikely

Short of just replacing stuff - my next thought is to find a shorter belt and do a power steering pump delete. I think that would work.
Is it possible to delete the A/C from path? (mine is on passenger side)

Thanks!

[Jesda]

Is it coming from the engine or under the car? For me it's an exhaust hanger rattle that I havent bothered fixing. Problem goes back to 2018.

[cbyrne]

You should not be considering a power steering pump delete for the symptoms you are describing.

Have you serviced the serp belt and tensioner? How many miles on it? It's normal for the tensioner to have a slight oscillation. The noise you're hearing is probably from elsewhere.

If you are not throwing any DTC or suffering from any driveability issues, then you could start by replacing the belt and tensioner, it's less than $100 in parts and an easy 30 minute job in the driveway with basic tools.

Video would help

[sabino56]

Originally Posted by Jesda

Is it coming from the engine or under the car? For me it's an exhaust hanger rattle that I havent bothered fixing. Problem goes back to 2018.

Thanks
It's coming from engine bay. Using a tube to ear, it seems loudest in area of alternator or around there. Sounds more like a "knock" than a "rattle" though that is of course, subjective. I took video/sound but can't attach here unfortunately.

[sabino56]

Originally Posted by cbyrne

You should not be considering a power steering pump delete for the symptoms you are describing.

Have you serviced the serp belt and tensioner? How many miles on it? It's normal for the tensioner to have a slight oscillation. The noise you're hearing is probably from elsewhere.

If you are not throwing any DTC or suffering from any driveability issues, then you could start by replacing the belt and tensioner, it's less than $100 in parts and an easy 30 minute job in the driveway with basic tools.

Video would help

Thanks
I replaced the serpentine belt within last year. I had another weird knocking sound then (different from this) which I finally tracked down to the bolts on the power steering pump backing out/loosening. I found it by getting a shorter belt and bypassing the power steering pump just to verify which thing was causing the problem.

I did not replace the tensioner at that time. Probably good to do so even if just for preventative maintenance at this point. Thanks, I will do that regardless.

No DTC (expect for washer fluid) and checked for errors on INPA also - no errors.

I did make a video which shows the idle dropping and noise starting, tensioner starting to jump a bit. It seems too big to attach. I can PM/email if interested.
I made mp3 of the sound from that and was able to zip to attach below.