polo wastegate rattle noise

**sambb** · 31-12-2020, 10:13 AM

I'd seafoam/subaru top engine clean it to rule out any gas leaks at gaskets on the hot side first. When I changed over my exhaust mani on the new car I reckon 2 bolts were still tight. Hot side leaks can flutter, squeal, whine etc which could account for it. If the noise went away with the N75 disconnected then it might point to a compressor side boost leak in the IC pipework that only breaks over above 6psi too I guess?

**simon k** · 31-12-2020, 04:54 PM

Originally Posted by sambb

I'd seafoam/subaru top engine clean it to rule out any gas leaks at gaskets on the hot side first. When I changed over my exhaust mani on the new car I reckon 2 bolts were still tight. Hot side leaks can flutter, squeal, whine etc which could account for it. If the noise went away with the N75 disconnected then it might point to a compressor side boost leak in the IC pipework that only breaks over above 6psi too I guess?

nah, I did all of that.. intake cleaner, checked the bolts, pressurised the intake tract

it only does it when it's building revs, if I put my left foot on the brake and accelerator flat on the floor it won't do it, so I don't think its a boost leak

**sambb** · 01-01-2021, 11:38 AM

whats the preload on the actuator rod like? they say 3mm (3 full turns on the end nut) is the K03 base setting. Maybe it has insufficient pre load and the flapper is rattling over the port at anything just above spring pressure?

**simon k** · 01-01-2021, 05:43 PM

I was pretty sure I'd done it properly when I had the turbo off, but I reset it anyway, no difference - what would happen if I made it 4mm preload?

**h100vw** · 01-01-2021, 07:36 PM

I'd add half a turn at a time. As you add preload the boost profile can alter drastically. Will become peaky AF and the ecu may be unable to catch over boost occurrences . So go gently

**bn1986** · 27-01-2021, 01:10 PM

Originally Posted by simon k

blast from the past...

my car has been making a noise like a cicada for the last 15,000k's - I finally thought about doing something to see what's doing it and disconnected the N75 today on the way home from work, noise went away.. I assume it's doing what Sean describes here

is it just annoying or is it doing damage to something?

Hey guys - just got notification in my spam folder about ppl digging up my old post.

The polo is long gone - driving a forester these days!

However - i never posted what the end outcome of all this was.

- Mechanic pulled the turbo off, and found a cracked exhaust housing.

Replaced the turbo, problem solved.

Im sure its not what you wanted to hear, but figure i'd give some closure on the matter.

the mechanic also installed the forge wastegate actuator - despite my asking him not to, and of course didnt tension the wastegate actuator correctly.

hope it doesnt turn out to be the housing as it was in my case.

Ben

**simon k** · 27-01-2021, 04:13 PM

Originally Posted by bn1986

- Mechanic pulled the turbo off, and found a cracked exhaust housing.

Replaced the turbo, problem solved.

hope it doesnt turn out to be the housing as it was in my case.

Thanks for getting back to me.. This is actually my suspicion, I've checked everything else. Sam gave me another turbo housing but there are cracks in that too.

I nearly took the manifold off the other day to see if there was a leak at the exhaust manifold.. I'm glad I didn't because I won't want to put a badly damaged turbo housing back on

**h100vw** · 27-01-2021, 06:16 PM

Have you got pictures of the cracks Simon? If you do go for a turbo swap, port that stock manifold for some free power and torque. I just did mine and it's a load better than the 034 I took off