2000 V40, engine rattle with higher RPMs

jcartermedia · Post by **jcartermedia** » 22 Jan 2018, 15:08

Hey all! I've been dealing with this 2000 V40 for a few months now and it seems to be developing a new sound that I haven't heard before.

I snapped a quick video that will illustrate what I mean much easier than I can describe:
https://youtu.be/Ki85OCuoG84

As the video captions say; when the car has cooled or has been cold for a while, there is a harsh rattle when starting it and when revving the engine above 1,300 or so RPM. This happens until it is 100% warmed up and not a moment before... It only started happening less than two months ago.

The check engine light comes on and goes off intermittently with what seems to be code P0420 every time - which I'm slowly looking into as budget allows. Oil level and coolant level are currently fine - it does have an oil leak and I had to top off the oil with maybe two quarts recently (Yikes, I know.. I just didn't realize it was going through it that quickly) and the coolant (which I filled with water at the time because I didn't have coolant, which now, I do).

Not sure what the rattling may entail and I'd prefer to get some ideas before I bring it to a shop for a diagnosis...

Any help/ideas would be greatly appreciated!!

Post by **alschnertz** » 24 Jan 2018, 06:15

It's really hard to hear in the video. Maybe open the hood and try there instead. You can rotate the throttle spool by hand under the hood to increase the RPMs.

Regardless, my alternator pulley has failed twice. First symptoms were rattling when cold...

jcartermedia · Post by **jcartermedia** » 24 Jan 2018, 10:17

Yeah, if you listen on decent enough speakers (not cell phone speaker) or headphones/earbuds it's easier to hear that rattling.

It does seem to be coming from the area around the alternator/timing belt area. Was thinking it was the case rattling but, I wondered why it would only do it when it's cold...?

Post by **alschnertz** » 24 Jan 2018, 10:56

There is a clutch inside the alternator pulley.
As to why it only makes noise when cold, I'm not sure, but that's when mine did it.
Granted, I replaced it before it rattled all the time.

Get a 2' piece of straight 5/8" heater hose.
Stick one end at your ear and use the other end as a stethoscope to isolate the sound's location.