Need the truth for some Weird boost leak test results?

[hellcat77]

I have a 98 Tsi, AWD. I just installed a new Bastard 20G turbo from Slowboy and a FMIC from Extreme. Now it runs pretty laggey, but still needs to be tuned. It does have the supporting fuel, exhaust and engine management mods installed and setup. Even though it holds 20 LBS to Redline, it still feels weak for what it should be pulling? Also has a Greddy Type S that I can't yet stop from fluttering?

One of the first things I tried to do was tested for boost leaks using a boost leak tester, but when I put in only <5lbs of pressure to the turbo intake, I heard this weird gurgling/Bubbling noise from the motor instead of finding a hissey leak?

I can't even finish the boost test the way the Vfaq shows how to because it won't hold any pressure at the intake inlet, as the pressure just bubbles/gurgles away?

And Wow it really seems like there alot of misinformation out there on the subject?

Please help me clear this up gurrgling once and for all!

I've been around to a several DSM boards and they all say this bubbling/gurgling sound is one or more of the following:

A. Normal, when not running and oil pressurized the air will slide past the turbos oil seals, blasting air through the turbo down through the dump tube into you oil pan.

B. Not normal you have bad oil seal in your turbo, and you need it fixed.

C. The Air is blowing buy your rings, valve seals, or egr into the crankcase?

D. You have a cracked Head or bad head gasket.

E.You need to turn the motor over to TDC before running a boost leak test?

F. You are hosed, and have Demon's or UFO's, sell you DSM?


Seems like a bunch of people have this same issue, yet there is no CLEAR cut answer out there to if it this gurgling sound is really is normal or not?

I did call Curt at Slowboy Racing, and he said if it didn't smoke it was ok, but he hadn't ever heard of the problem, so this made me nervous, as none of my other turbos gurgled when they were boost leak tested.

Like I told Curt at slowboy, if there's a issue on this brand new turbo with the seal, I'd rather know NOW, stop and ship it back for repair, than to run it and blow the turbo out completely.

This brand new turbo cost me $1100.00 and theres no way I'm going be the one getting the shaft on it if somethings wrong with it!


Is my Brand NEW turbo already shot or is this gurgling normal or is there another real answer?


TIA........


Howie

 

[hellcat77]

Now this morning, I go out and try another test, no gurgles this time, just starts to build a tiny bit of pressure and I now hear it air rushing straight out though the oil filler hole, and still not holding any pressure?

WTF?

Like what ever oil that was gurgling last night when I did the same test, had drained down and now I'm just hearing the raw "leak"?

How can this happen?

Do I really need the motor at TDC to run this Boost leak test or is this deal really just a red herring or what?

 

[L2RTSiAWD]

So you have the oil cap on but you hear are rushing out of it? Is that what you mean by "oil filler hole"

 

[NOSLO2PT0]

I now hear it air rushing straight out though the oil filler hole, and still not holding any pressure?

Sounds like you got some toasted rings on your pistons. Do a leakdown test to verify.

 

[oldman]

Do I really need the motor at TDC to run this Boost leak test or is this deal really just a red herring or what?

No, TDC is the worst place to be during a pressure test. #1 tdc = #4 valve overlap, intake and exhaust valves are both open resulting in air rushing out of the exhaust.

A. Normal, when not running and oil pressurized the air will slide past the turbos oil seals, blasting air through the turbo down through the dump tube into you oil pan.

This is correct, if and only if there are no signs of oil leakage during operation.

This is what I think you should do.

1. Move the tester to the TB elbow for now, we'll move the tester back to the turbo inlet once you're able to pressurize up to 20psi at the TB elbow. Listen for leaks at the oil cap and your tail pipe.

2. If you hear air coming out of the tail pipe, turn the crank to about 30* after tdc. If problem persists, most likely your EGR is stuck open.

3. If you are sure air is leaking into the crankcase, disconnect the pcv hose from intake manifold and plug up the nipple on the IM. If problem solved or the intake pressure increases, replace the pcv with an OEM one. If problem persists, go to 4.

4. Perform a dry/wet compression test, this will tell you if air is getting past the rings. If compression checks out, you're probably leaking air through the valve seals.

As for the spooling problem.

1. Make sure that there are no exhaust leaks before the O2 housing.

2. Make sure that the flapper is fully closed when the actuator arm is attached.

3. Pre-load the actuator to make sure the flapper isn't being blown open by the force of the exhaust gas.

Hope this helped. Good luck.

 

[hellcat77]

Thanks OLDMAN and you other tuners , I'll need to get to this tonight as I need to get to work right now.

I'll be sure to repost my results lster this evening......

Thanks MUCH again!


Howie

 

[hellcat77]

So you have the oil cap on but you hear are rushing out of it? Is that what you mean by "oil filler hole"

Where it says "OIL" and you fill the oil to on top of the valve cover?

 

[1fast97gsx]

Yep that cap is called the "oil cap" ... sounds to me like your pcv is stuck open. Do the pcv removal mod and do another boost leak test and see what happens.

 

[hellcat77]

Ok replacing the PCV helped, with the valve cover hissing sound but I'm still playing with a bunch of boost leaks all over the TB with the bigger turbo and FMIC.

Did some test runs and according to DSMLINK I'm running at ~18/1 A/F pretty much arcross the RPM board?

So when I tried to richen it up it to be 11/1 the car bucked, bogged and backfired? Like it was WAY to rich even though DSMLINK says it's right on?

WTF? So if I have mega boost leaks I'd be running richer than what was visable to the DSMLINK as I would be leaking post metered air right?

So it could make the DSMLINK think so 18/1 A/F reading must run better <with boost leaks,as it's leaking a good part of that 18> than setting it to 11/1 as I'm probably running 8/1 with all the boost leaks?

Or is the A/F ratio that DSMLINK gives you gospel directly from the o2 sensor period?

TIA..........

 

[oldman]

You have no business doing test runs until all leaks are fixed.

 

[hellcat77]

So I need to be able to hold 20lbs for 30 seconds to pass the Leak test then correct?

I'm not even close, back tot the drawingboard I guess?

 

[oldman]

So I need to be able to hold 20lbs for 30 seconds to pass the Leak test then correct?

At least to what ever your boost will be set to.

I'm not even close, back tot the drawingboard I guess?

Be patient, it's hard because this is your first leak test. A leak test should be done regularly as new leaks can develop due to many reasons.

 

[hellcat77]

Doing more leak testing, that pcv valve I JUST bought to replace the leaking one is also leaking pretty bad as well.

What's going to me a bigger PIA is that I'm sure I found a huge boost leak around the TB and TB shaft.

I looking at the FAQ it looks like a pretty complex job to rebuild the TB for a NOOB like me.

Thinking of just buying this rebuilt one off Ebay that has a "half shaft mod", has all new seals, is glass beaded, with all gaskets, is honed to 80mm and he wants $100.00 after the $40.00 core credit.

Ever heard of this half shaft mod?

He claims that this new TB will give better response, and better flow?

It might be a good idea for me, then I can start searching for the NEXT boost leak

 

[oldman]

Doing more leak testing, that pcv valve I JUST bought to replace the leaking one is also leaking pretty bad as well.

Make sure you replace it with an OEM one, generic ones from autozone and the likes are known to leak.

What's going to me a bigger PIA is that I'm sure I found a huge boost leak around the TB and TB shaft. I looking at the FAQ it looks like a pretty complex job to rebuild the TB for a NOOB like me.

Not that bad really and many noob have done it. It's probably the shaft seal, BISS o-ring or both.

It might be a good idea for me, then I can start searching for the NEXT boost leak

Before you remove the TB, spay soapy water around IM and injector seals then repeat test. You wouldn't want to reinstall the TB just to find out they're leaking as well and have to remove the TB again.

 

[hellcat77]

I was talking to a local "DSM Guru", and he says it's totally "anal" to even consider a TB shaft leak as serious enough to rebuild it?

He said that the turbo will more than make up of these smaller type leaks?

And it was BS to even worry about them?

I'm just trying to find the right answer, don't mean to dis anyone at all?

Please give me just the facts so I can tell this guy I'm not "anal" while rebuilding the TB!

 

[oldman]

I was talking to a local "DSM Guru", and he says it's totally "anal" to even consider a TB shaft leak as serious enough to rebuild it?

Everyone is entitle to their opinions and run their cars however they desire. If you ask me, a leak is a leak, small leaks adds up to big leaks. Especially when the "small leak" is near TB and IM which can cause pita idle surge.

Please give me just the facts so I can tell this guy I'm not "anal" while rebuilding the TB!

Do a search on this subject on your own, make your own decisions and don't worry so much about what others think. There is nothing wrong with being "anal" about your car, most serious DSMers whom are able to keep it on the road on a consistant bases are probably extremely anal when it comes to their rides.