Wierd Boost leak test results?

howslowcanyougo · 07-26-2005

--------------------------------------------------------------------------------

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 your 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?

Now this morning, I go out and try another leak 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?

?

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?

niterydr · 07-26-2005

When you are doing the 'boost' leak test, pop the radiator cap, if its really bad, you'll notice bubbles in the fluid, then you know you have a blown headgasket.
Are you sure your not leaking out the intake manifold?
Where the motor is at in its revolution shouldn't matter for a boost leak test. The point is to pressurize the intercooler/intake system, post turbo, to help find leaks. If you are really worried about the motor, have a compression/leakdown test done. About the blown seal pressurizing the oil? Never heard of that one before. I would imagine the car would smoke really bad if that were the case.

**JET** · 07-26-2005

I am going with B, C or D. Like Swanny said, take off the radiator cap and see if the coolant is bubbling. I have never had this in a car either. I am just trying to speculate as to what is happening. If the coolant isn't bubbling, then do the compression/leak down test.

howslowcanyougo · 07-26-2005

Replaced a newer PCV valve and the hissing noise out of the valve cover got alot less BUT it's still not holding boost.

Going to test right off the TB elbow and repost.

Thx!

Howie

howslowcanyougo · 07-27-2005

Ok no bubbles in the Radiator? But my 2 month old PVC valve was leaking BAD into the V/C, AND the TB elbow, and the solinoid device <what's that called?> on the TB is leaking as well.

Need to get all these damm boost leaks cleaned up fast before I go down to RC's AWD dyno for some wideband time next week!

Bottomline on the turbo is that it's holding boost, not blowing smoke, has no shaftpaly, has no oil sitting compressor side and the vendor said that bubbling is "normal"?

I just can't worry about it until something happens now I guess?

Thanks again for your excellent insights fellas!!

howslowcanyougo · 07-27-2005

Ok still playing with a bunch of boost leaks here with the bigger turbo and FMIC, but 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......

**JET** · 07-27-2005

DSMlink is guessing at the AFR by using the amount of air going in and the fuel going in. A boost leak is going to mess it up using the stock MAS.

Alpine TSi · 07-28-2005

Did you have all you settings correctly plugged in for the AFratio properties? It will do a decent job if all the settings are correct.