Paging 1.8t Gurus, did a pressure test.

[OptimusGlen]

car: Audi TT 225
mods:
-it was chipped at one point but I think a dealership along the way re-flashed the ecu or something.
-new aftermarket piston style DV (stock rated spring, no shims), new factory N75
-Samco TIP

I did a pressure check, when I drive I get a lot of air swooshing sounds (the entire time I'm accelerating, not just at shifts)

I used the soup can technique and it seems to work quite well. I plugged the pvc tube because the plastic seemed too hard to just clamp off.

I pressurize the system, except it doesn't build pressure very quickly. I notice air leaking from the oil cap. I can not hear any other leaks, but most of the air is out of the system before I can hear anything from anywhere else, also hard to hear any other leak over the oil cap leak.

Some guy on vortex in another similar thread said the rings were shot on another guys car. I don't believe this is true for me, no burning of oil etc.

1: Should there be air able to come from the oil cap at all?

2: Will replacement of the cap solve this "boost leak" ?

[OptimusGlen]

upon closer inspection it looks like the leak is coming from somewhere under the fuel rail on that side, thinking maybe the intake manifold gasket. Although when I remove the oil cap it will not make any pressure when I charge up the intake.

[SLK]

well normally in the past if you pressurize the system and there is air leaking through and out the cap then there is a leak in the rings. It may not be big now. It could just be developing. How many miles are on the car? ALSO if the used to have a chip and maybe some other previous mods maybe the car was beat on alot causing the rings to go prematurely.

[OptimusGlen]

Previous owners were like 40yrs. old, married couple. I have receipts for everything done to the car since it was brand new, so I know all the mods etc. Everything was installed at dealers, right down to the valve-stem caps.

About 52k on the car now.

Also, it's had the same "swooshing" sound under acceleration since I've owned it, and it used to boost to 17 (peak) no problem.

I will try to get it some place to get a pressure check on the cyl's.

[StickiestOfTheIckiest]

yeah, do a pressure check on the cylinders and see where they are at

[Die Frau]

The oil cap should not be holding any boost preasure.

[autobahn]

glen, I'd ask over at MNAudi, there's a bunch of guys there who do pressure tests on 1.8ts all the time, they would probably know what that means.

I do get the feeling that you might have problems with the rings. Do a traditional compression test and see what you get

[KOOTER]

How are you presureizing the carnkcase?

[flippinvw]

Yeah, are you just hearing air going through the oil breather? Isn't that part of the oil cap on the 1.8T?

Maybe you're pressurizing the wrong side of the pistons ;) How I don't know, I have no idea what a soup can mod or whatever is.

[flippinvw]

Chuck, would putting soapy water in the suspicious area help or is it too hot? What about spraying carb cleaner there? Do those tricks still work on the newer cars?

[magilson]

How are you presureizing the carnkcase?

1.8 PCV's suck. Check them.

[sKasse]

I think I have those same "swooshing" noises that you are talking about and have really wanted to do a pressure test lately, but havent had the time to make the soup can thingy.

It will be really interesting to hear what you find.

[Janasty]

1.8 PCV's suck. Check them.

yes

glen try to get enough air in the system and put your hand underneath the intake manifold, under there is a series of vacuum lines and pcv lines...over time the rubber weathers and becomes almost gooey and split open. With the engine idling can you hear any hissing noises under the intake manifold?

also, air coming out of the oil cap is normal while doing a pressure test.