kbonarek

Alright, this is gonna be a little long.

I recently replaced my N75 valve to address some boost flutter issues and opened Pandoras box.

Old N75 078 906 283 B, NEW 034 906 283 H

Initial problem was overboosting after the N75 install and with some pressure testing and some patience, the WG lines had a leak where they tee off. Fixed That problem, no more WG leaks and both actuate nicely.

Next problem...spider hose assembly at the rear was broken where it goes to the passenger side valve cover before the N75 valve...replaced that section of hose, no other leaks in spider assembly.

Here's where it gets interesting. Car now only pushes 10psi of boost with the n75 plugged in. Requested is around 18-19. Overboosts like crazy with it UNPLUGGED...should be 7psi unplugged, right?

Pressure tested the car. What's odd is that I removed the pressure limiting valve that stems off the y-pipe and capped it off...all the pressure bleeds off through the valve on the spider assembly. Plugged the valve with my trusty finger...pressure now leaking out from behind the passenger head where the camshaft tensioner seals to the head.

So...the camshaft tensioner seal is bad, already knew that, but why is the pressure coming through the spider assembly...1 way valve forked?

Also, the BPV's are good, both were checked and are recently replaced 710N's. All the boost hoses, I have faith are not leaking, It's an entire samco kit that was meticulously installed.

I need some help before I burn my car...please.

Plan is to get an updated spider hose assembly and replace the camshaft tensioner seals...am I moving in the right direction?

And why the hell would it overboost with the N75 unplugged with no leaks in the WG lines? The long end of the N75 goes to the wastegate lines, the bottom one goes to the spider assembly (atmosphere) and the short to the pressure side of the turbos...also for this experiment, the MBC has been removed.

I'm lost...

K04-S4

Your new N75 H valve may not be for your car. Did you find that the new one would not physically mount exactly the same as the old one? The OE valve that most folks trust for the 2.7T is the B valve.

Did you get the new H valve from 034 motorsports? I ordered N75 from them for the 2.7T and they sent me the 034 906 283 H valve which does not mount the same as my B so I never installed it. I called dealer parts about the H valve and they said it is an Audi valve for a host of models but not for 2.7T. That was the end of my experience with the H valve on the 2.7T. Anyone want to purchase my brand new H valve?

Agreed spider hose one way valve is likely failed based on your description, fairly common with age. The valve is marked with an arrow showing flow direction. When in boost, this valve leaking can excessively pressurize your crankcase and help blow engine seals. I just replaced my spider hose assembly for the updated "cold weather" factory one and it's a bit of a bugger to install with engine in car, prepare to spend some fiddle time

My .02

kbonarek

Ya, the n75 was from 034. Dang...guess i'll have to spring for a "b" now. The lower half (connections are 90 deg. off from the H but the install was simple. Advertised as follows:

034H "Race" Valve - OEM style N75 valve, this is the fastest reacting valve with the higest boost capacity of the N75 valves we've tested. Also works well for universal application boost control like with our new Stage I and IIc ECU's. Also known as the "H" valve and came stock on 2.2 Turbo 5-cylinder applications like the 3B and AAN, offers a 1-2 psi boost increase in newer 1.8t and 2.7t applications.

I figure a quicker reacting valve would mean more precise control over the wastegates...silly me.

What did the updated spider hose set you back?


ECS has it around 130 i think.

K04-S4

I purchased new cold weather spider hose assembly locally for ~$140 cdn.