Help with boost leak

[jfritz27]

Hey guys, hoping for any input here...

Since I put on my VRSF charge pipes last year (in combo with BMC drop-ins), I've noticed a more prominent high-pitched whine during induction. I have BM3, logs supposedly looked OK per BM3 tech support, they said that sound is normal with those pipes and drop-ins.

I recently had my plugs changed under warranty at the dealer, and this whine is definitely more prominent now. I can't say for sure that I can appreciate a loss of power, it may be subtle, but I'm thinking this is a relatively small leak (which paradoxically due to flow dynamics could lead to a louder, more prominent high-pitched sound as opposed to a more wide-open gushing leak -- hence perceived power may not be affected too much). I took it back to them, supposedly one of the meth bung plugs (I don't use meth) was missing, so they plugged (that's good), but the whine is still there, just as bad. I'm wondering if they missed a slight mis-seating of one of the pipes at the turbo. Two questions:

1. Besides the meth bungs, hose clamps at the IC, and connections to turbos, what other points/pathways if any should I be considering as a source of a boost leak?

2. I have an OCC, and the tech mentioned something about the hoses there not being connected as a source of the leak. That may or may not have been true, but regardless I did not think the PCV path with respect to a catch can was exposed to boost pressure? After all, the hoses involved (stock, and what comes with the OCC) do not connect with clamps or anything that would hold pressure. Does this make sense in any way?

Thx much

EDIT -- Link to video demonstrating the noise: https://drive.google.com/file/d/1EF1...ew?usp=sharing

[TopJimmy]

Originally Posted by jfritz27

Two questions:

1. Besides the meth bungs, hose clamps at the IC, and connections to turbos, what other points/pathways if any should I be considering as a source of a boost leak?

2. I have an OCC, and the tech mentioned something about the hoses there not being connected as a source of the leak. That may or may not have been true, but regardless I did not think the PCV path with respect to a catch can was exposed to boost pressure? After all, the hoses involved (stock, and what comes with the OCC) do not connect with clamps or anything that would hold pressure. Does this make sense in any way?

1. Those are the leak points on the hot side. Check your airboxes and see if someone added charcoals during service. Airbox/ intake path tubing leaks (usually loose clamps) screech a little. Feel around TMIC for leaks/cracks (temp sensor break off?). Feel around cold side pipe and J for leaks. Me... I'd disassemble the chargepipes, check thoroughly (crack, pinhole, o-ring missing?), blue drop of Loctite on the bung plugs, clean couplers, reassemble.

2. OCC is on a vacuum side. It doesn't need clamps, but I use them on mine. A leak here can also make noise (just suction, in bad case PCV squeal), but not like turbo spool. Use some cheap heater hose and a pair of nice clamps to bypass and rule it out. Reinstall OCC hose path later using the nice clamps.

[jfritz27]

Originally Posted by TopJimmy

1. Those are the leak points on the hot side. Check your airboxes and see if someone added charcoals during service. Airbox/ intake path tubing leaks (usually loose clamps) screech a little. Feel around TMIC for leaks/cracks (temp sensor break off?). Feel around cold side pipe and J for leaks. Me... I'd disassemble the chargepipes, check thoroughly (crack, pinhole, o-ring missing?), blue drop of Loctite on the bung plugs, clean couplers, reassemble.

2. OCC is on a vacuum side. It doesn't need clamps, but I use them on mine. A leak here can also make noise (just suction, in bad case PCV squeal), but not like turbo spool. Use some cheap heater hose and a pair of nice clamps to bypass and rule it out. Reinstall OCC hose path later using the nice clamps.

Thanks much for that advice. I added to my post a link to a video exhibiting the noise... any chance the character of the noise helps localize to your better trained ear?

[behindthen0thing]

That sound is strange, like a whistle.
If you have a boost leak it will be anywhere between the turbo outlet to the intake manifold.

To change the plugs they would have had to remove your charge pipes, and at least move your charge air cooler over.

You should be able to see a boost leak on a BM3 log. you would notice a high WGDC and also a boost deviation,

[TopJimmy]

Sorry, not sure.
Check this, but prolly different.

https://www.bimmerpost.com/forums/sh...php?p=25154848

[jfritz27]

Originally Posted by TopJimmy

Sorry, not sure.
Check this, but prolly different.

https://www.bimmerpost.com/forums/sh...php?p=25154848

Thanks.... yeah, that's different. My sound is clearly only present (I think) when under boost. It's never there at idle or when lightly on the throttle.

Above when you said check for leaks by feeling around, obviously you mean at idle, maybe with someone just giving it some throttle while parked?

If I can tomorrow maybe I'll pull another log and post up if anyone cares to take a look. I'm certainly not very skilled at reading them, but I know that we're looking at wastegate and boost actual vs target

[TopJimmy]

Originally Posted by jfritz27

Thanks.... yeah, that's different. My sound is clearly only present (I think) when under boost. It's never there at idle or when lightly on the throttle.

Above when you said check for leaks by feeling around, obviously you mean at idle, maybe with someone just giving it some throttle while parked?

If I can tomorrow maybe I'll pull another log and post up if anyone cares to take a look. I'm certainly not very skilled at reading them, but I know that we're looking at wastegate and boost actual vs target

Yes, check at idle. No need to have a foot on the gas. There's enough pressure. If you do decide to rev stick to 2K RPM.

[red_guapo]

its your charge pipes, mine has done it twice now. loosen at the charge cooler and make sure their pressed in and then tighten.

[White340]

Would some type of smoke help find the leak? Like insense? Cheap hack that might be able to pinpoint where it's coming from.

[Weechard]

Originally Posted by White340

Would some type of smoke help find the leak? Like insense? Cheap hack that might be able to pinpoint where it's coming from.

I had a similar sound after installing vrsf cp's. My issue was, I used my oem e-torx bolts opposed to the allen head ones provided by VRSF. So the CP's weren't seated properly to the turbos. Goes without saying but make sure you transfer the cp gasket to the new cp. Hope you get the issue figured out.

[behindthen0thing]

There's a vacuum in there at idle. There's no pressure.

[jfritz27]

Just to follow-up here in case anyone searches for help with boost leaks in future... but I ended up replacing the VRSF's with Mishimoto's, and all noises gone.

Can't say I was ever able to pinpoint where the leak was exactly, but suspect in part related to my dealer re-attaching the rear pipe loosely at the turbo, using a totally random hex head screw; that area seemed loose when I detached (but I had an abnormal noise from the get-go when I first installed the pipes myself, so something was never right all along with these VRSFs). I ended up getting new OEM gaskets and E-torx bolts that fit to the turbo, just to be sure. I can also attest to the fitment of the Mishis as others have -- definitely on point.

Just a tip regarding those e-torx bolts at the turbo -- it makes the install easier if you first pass the bolt through the collar on the charge pipe, ensuring that the washer-like portion of the bolt head is tucked into the little grove at the end of the pipe where it needs to ultimately sit. If you don't do this first, the angle makes it very difficult to get that bolt to seat properly once the pipe is fitted to the turbo. Prior to seating the pipe, I taped the bolt in place to ensure I didn't lose it and that it maintained proper position.

[tomlong]

A 10mm 10.9 grade bolt works fine too. Easier to get stubby 10mm wrench in there.

I've had my fair share of bad fitting aftermarket charge pipes. I carry an E12, E14, 6mm, 10mm, and 13mm in the car along with your standard tools in case they decide to pop off for no reason.

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