Resolved Water dribble sound while boost leak testing!

[Kryndon]

So I finally installed my custom O2 housing (+ wastegate) and I immediately tried doing a BLT.

I was pressurizing the system to 15-16 psi, however as I filled the system more and more with air, a very peculiar noise that sounds exactly like water drops started appearing. Or maybe it sounds like bubbles suddenly emerging from a clogged drain? You can very clearly hear it in the two videos I recorded. I am stumped. My first panic guess was the air somehow going into my coolant system but I saw no bubbles up at the cap. What do you think?

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[2gmitsueclipse]

The sound you are hearing is air escaping around the seals in the turbo since no oil pressure is present in system. The pressurized air is traveling down the oil drain and into the oil pan causing the "bubbling" you are hearing. I would reccomend pressure testing after the turbo.

 

[Kryndon]

The sound you are hearing is air escaping around the seals in the turbo since no oil pressure is present in system. The pressurized air is traveling down the oil drain and into the oil pan causing the "bubbling" you are hearing. I would reccomend pressure testing after the turbo.

I am aware that air gets past the journal bearings and into the crank case while doing static BLT. However, I have always tested it this way at the turbo inlet and it never made this exact sound. I'm not talking about the 'whooshing' air sound, but rather the "drop-drop-drop" noise. If you're right and it is just air flowing down the return pipe and into the sump, that means the oil level would have been above the entry of the return. Maybe this time I've got more oil into the pan than the last time I did a BLT, and that's why I'm hearing it?

 

[Archer Fabrications]

I wouod boost leak test from your lower ic piping or the inlet of your intercooler, avoids pressurizing the turbo, but still gets all the air into the rest of the system. As long as you know your turbo doesnt leak air from the snap ring side of the compressor housing (common on holsets for instance)

 

[DSMPT]

I am aware that air gets past the journal bearings and into the crank case while doing static BLT. However, I have always tested it this way at the turbo inlet and it never made this exact sound. I'm not talking about the 'whooshing' air sound, but rather the "drop-drop-drop" noise. If you're right and it is just air flowing down the return pipe and into the sump, that means the oil level would have been above the entry of the return. Maybe this time I've got more oil into the pan than the last time I did a BLT, and that's why I'm hearing it?

That's a common sound if you apply the air pressure from the turbo inlet. It doesn't always mean you have high oil level. Many cases some oil slightly remains at the bottom of oil return line or/and around oil pan return inlet because of angle or maybe smashed. And that makes the sound. The best way is to apply the air pressure from the inlet of lower intercooler pipe after the turbo as everyone above recommends.

 

[Kryndon]

Thanks to everyone, Nate was right on the money! I completely forgot that while doing this particular BLT, I had the entire rear end of the car high up in the air because I was in a tire shop getting some tires fitted. That would no doubt make the oil level flow into the return line and block it, thus allowing the pressurized air flowing through the journals to also flow through that bit of oil and make bubbly sounds

Marked as resolved!

 

[Archer Fabrications]

Thanks to everyone, Nate was right on the money! I completely forgot that while doing this particular BLT, I had the entire rear end of the car high up in the air because I was in a tire shop getting some tires fitted. That would no doubt make the oil level flow into the return line and block it, thus allowing the pressurized air flowing through the journals to also flow through that bit of oil and make bubbly sounds

Marked as resolved!

Gotta include all the crucial, even sometimes
Obvious details that we On the fourms have no way of seeing glad you got it sorted!

 

[JusMX141]

The position of the engine in the bay means the oil pan isn't the lowest point- there will always be oil laying in the bottom of the drain tube when the engine is off. Not the best design by far, but it's what we have to work with and lots of aftermarket turbos have drainage issues because of this.

There's no point to checking for boost leaks at the compressor cover inlet unless you're seeing if the cover is sealing properly. The turbo itself will always allow pressure to leak into the bearing housing because of the dynamic sealing ring on the compressor side. The only way to get a perfect seal is to go back to 1970's technology with a carbon seal that constantly drags on the shaft which is outdated and unnecessary.

Summary: always pressurize the charge piping after the compressor cover when testing for leaks.

You must be logged in to view this image or video.