Is the engine in my Boxster broken?

I am not sure, but if so I won't really be surprised.  It has started making a metallic rattle at idle, especially when it's warm and I come up to a stoplight, then if I am waiting long enough the sound goes away.  From outside the car it sounds more like a sewing machine/noisy fuel injector sound, but from inside the car it sounds louder and has been slowly getting worse.  It still runs fine otherwise and has enough oil in it and isn't overdue for an oil change, and last time I changed the oil I changed the filter housing too.  I figure anything that would be made worse by driving it would be mostly cheaply fixed by just swapping the whole engine for another used one, but is it likely to explode soon?  It definitely didn't sound that way when I got it, nor did any of the other ones I have driven, but with 150k miles I don't expect it to last that much longer anyway.

Isn't that the classic IMS bearing sound?

Could be the timing chain tensioners. 

It's probably something terrible and expensive.

But...

Any check engine light?

Lots of people have had bad noises in these that was simply a loose spark plug.

Check the exhaust for loose heat shields and cracks.

Take a look at the serpentine belt and accessories that are run by it. I know of at least one case of 'IMS failure' that was a bad AC compressor pully that took out the belt.

Good luck.

What you are hearing is probably the timing chain guides and possibly tensioners. What year Boxster (information like this is useful)? In the earlier generations of those engines the timing chain guides wearing away is a known issue, especially with that kind of mileage. Unfortunately, replacement of the guides isn't super easy, but it is doable with the engine in the car.

My 911 did that...it was the water pump.  There are pleanty of good reasons to be scared with M9X powered Porsches, but don't jump to the worst conclusion first.  Pull the serp belt and check all the pulleys.  Give it a brief start to see if the noise persists.  

For timing chain guide issues or an indicator of IMS issues, look for camshaft deviation readings on Durametric (or similar good tool.)  You're looking for readings less than +/- 6 degrees on both banks.

If that's suspect, drop the pan (thankfully easy to do.)  If it's timing chain guides, the remnants will be there.  If you see a bunch of other sparkly detritus, that sucks.

Could also be the catalytic converter. My wife's 986 rattles from them but they're too expensive to replace just for a rattle. For now.

Can you send an oil sample to Blackstone or similar?  They can tell you if their is foreign material in the oil, and tell you what they are so you can make an educated assessments of what may have failed.  If possible DO NOT RUN THE ENGINE until you have a reasonable diagnosis.  

It still runs fine otherwise, just makes a unpleasant sounding noise at idle.  I don't think it's the IMS based on other peoples description of what kind of noise it makes when they fail and some videos I found. 

It's a 2000 base model with the 2.7.  My best guess is that either it's something that sounds bad but actually isn't, or it's something to do with the lifters or timing chain tensioners. 

I had an OM603 diesel Mercedes that had noisy lifters (not really any concern on those) and it sounded similar to this.  The noise definitely happens most when it's warm at idle after driving for a bit, and it will abruptly stop after idling for long enough.

I changed the water pump and all the pullies except the tensioner when I got it and have only put about 4k miles on it since then, but I will check them all again. 

The car was cheap enough that I don't think anything that would damage the engine to keep driving it would be worth fixing vs swapping in another used engine (or just buying another car), but I will at least try to figure out what's actually wrong with it if I can. 

I had a Boxster with a failed muffler that rattled like that.

I used its J tubes to make an intake manifold for a peripheral port rotary 

Clutch release bearing?

If you think it might be lifter noise, try a different oil. 

Wife's car had that, tinny heat shield over the  Cat was missing two screws.

I took the engine cover off to see if I could hear or see anything else, and it still sounds like a valve train noise, more from the passenger side than the drivers side like it sounds with the cover on.  I also drained the oil and there was a small amount of magnetic bits, copper, and timing chain guide crumbs but not in an amount that seemed overly concerning, and I cut the oil filter open and there was nothing inside. 

I filled it up with oil (with a magnetic drain plug this time) and I think I will just not worry about it until it becomes obvious what's wrong.  It already sounds bad enough to be "bad engine" price if I wanted to sell it, but I have been driving it and it still runs fine otherwise.  I was hoping to get more like 20-30k miles out of it than 5k, but I guess there is a reason you never seen Boxsters for sale with over 200k miles on them. 

https://www.renegadehybrids.com/boxls.html

You know what you must do...

You should have saved some of the oil for analysis.  They give you metrics on contaminants and advise how bad the numbers are.

Apexcarver said:

https://www.renegadehybrids.com/boxls.html

 

You know what you must do...

No personal experience,  but I've never heard anything good about Renegade hybrids service or quality.

Adrian_Thompson (Forum Supporter) said:

Apexcarver said:

https://www.renegadehybrids.com/boxls.html

 

You know what you must do...

No personal experience,  but I've never heard anything good about Renegade hybrids service or quality.

Good to know. I know nothing about the company, just love the concept of an ls powered boxster

I don't know about the company one way or the other but I've driven several Renegade equipped cars on track (Boxster & 914).

The cars were indeed fun to drive.  With the 914 it definitely changed the character of the car. I like the original layout better.