Kyle22rte

Where to start....
My lady and I were driving up the coast when her car began to make noise under acceleration. Pretty much in synch w/ the boost guage (oh, it's an 01 9-5 2.3t, by the way).
It wasn't too bad and we're both broke and busy so we let it go.

It progressively got worse. I gave it a once-over and couldn't find it so we took it to a local saab specialist for a diagnosis
I took him for a ride and explained to him that the noise was coming from the exhaust side of the engine, perhaps more toward the tranny than the front of the engine. In the vacuum pump/BOV region approximately.

Got the diagnosis back that the turbo was bad. He said the impeller had so much thrust play that it was hitting the housing. Sounded plausible, but w/ a $2000 estimate I thought I'd verify it.

Took off the exhaust and intake pipes from the turbo and it was as tight as can be. Just a TINY bit of vertical and no thrust play but nothing to be concerned with. He was obviously scamming us.

So since then I've done my best to check for vacuum leaks, I've tested the BOV and it checks out, and I've even taken the cam bearing caps off to look for a spun cam bearing. the journals of the exhaust cam are sort of spotted like they've run on really hot oil or something, but no scoring at all.

It really sounds like it's coming from the cylinder head on the exhaust side but it could be from the turbo, vacuum pump, or who knows what.

it's not a ticking like you'd normally hear from a bad lifter, it's more like a something is bound up when it's trying to spin fast and it emits a really high-pitched groan. Only when the car is hot, though.

Turbo only has 15,000 or so miles on it since being replace new.

Sorry for the long post!

Any ideas? Maybe a wastegate or something?

Roto

Ugh...this is a tough one to diagnose over the internet. I know you said you looked at the turbo, but can you take the compressor housing off and check for marks on the housing? That's the only way to check for sure. Turbos can fail very quickly if the recirculation valve stops functioning properly (or there's a massive vacuum leak) and that would produce exactly what you're describing, in fact I just went through that. My BOV failed, but was still sort of blowing off so I didn't catch it quick enough and it ruined a brand new thrust bearing. $2000 is a bit steep though, turbochargers.com charge a bit under $500 to rebuild one, and it sounds like you have the skills to do the rest.

Kyle22rte

yeah 2000 was 1000 for the part and then a bunch of other stuff he wanted to do.

i could probably find time to take off the compressor housing, but I am sure there is no thrust play. I reached in w/ some needle nose pliers and grabbed the center of the turbine and pushed back and forth---and nothing.

I had the BOV off and used a hand-vacuum pump to test it and I could see the diaphragm move and stay indefinitely. Do they fail in any other way than a cracked diaphragm? It didn't seem to stick or anything but I'm a toyota guy so what do I know...!

Roto

hm...wierd to say the least. You're not getting a check engine light either? It would really help if you could throw the car on a dyno since you could be right there with the hood open listening for where the noise is coming from...and it won't cost you more than $100 for a couple of pulls.

Kyle22rte

No check engine light. It makes the noise when parked with someone revving it for me, but only after driving it to get it up to full temp. I've even put a stethoscope on the various parts and it's not obvious what it is. definitely the exhaust side of the engine, and it sounds like it's above the turbo like in the head around the #4 cylinder but sounds can be weird so i don't rule out anything in that vicinity.

I tried to remove the vacuum pump to inspect it but it doesn't seem to want to come out even after being unbolted and lightly hammered, pried, etc. There's what looks like a cam bearing cap that surrounds where it goes in the head that's fastened with 2 T40 torx bolts but they're so tight they twisted my craftsman torx socket! I'm thinking since it's the kind of torx w/ the nub in the middle that maybe they want it to stay on.

Do wastegates ever make such noises? I'm thinkin it could be something turbo-related but not the turbo itself since there's no shaft play.

Kyle22rte

Wow, i feel almost as stupid as those mechanics are corrupt! It had one semi-loose bolt on the manifold/turbo flange. It must have been causing an exhaust leak that I couldn't feel through my latex gloves that hit just the right pitch. I've never heard an exhaust leak like that before but for a $0 repair, I'll take it!

thanks

FastBMW123

For me, this was the tensioner pulley. Use a stethoscope or piece of hose to help diagnose the pulley.
Fix this before it shreds your belt and strands you...
________
GSV-R800

Roto

Nice... good to hear it was so simple of a fix.

esr1973

I just read your first post describing your problem. My car is exhibiting the exact same symptoms. It gets hot them makes a horrible sound just like you are describing once it is hot. Its coming from the same place as you described as well. I am about to pull the valve cover and check the cam bearings to see if that is it.

Just started doing this after I replaced the head gasket as well.

Did you discover what was causing your problem?