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View Full Version : Wastegate Sticks Open



zak
03-13-2012, 05:32 AM
A month or so ago I posted a thread hear about a 0422 code and low, slow to build boost.

The cat code is very sporadic and not a real issue--MIL pops on then off every now and again.

But I did find the culprit of the low, slow boost: my wastegate will occasionally stick open. I am not sure if it's because of a bad actuator or if the linkage in the housing is sticking. I can wiggle the rod and I am back to normal boost (so I know the DV, N75, wastegate disc itself, turbines, cat, etc. are good), but after a while it sticks open again and my car's a dog.

Does anyone know what makes the wastegate close? I assume a spring, but I don't know if it is on the actuator or the flap end. Basically, do I need a new turbo or a new actuator?

walky_talky20
03-13-2012, 06:02 AM
I had this problem on a Volvo once. It was a failure of the wastegate flapper's "pivot". It had a bushing of sorts that had worn out and created way too much slop. The slop allowed the pivot to bind, creating too much resistance for the spring to close it. Actually the behavior was very interesting because movement in both directions was sticky. It would be stuck closed way past the spring pressure, creating a huge boost spike. Then, "PSSSSHHHH": you would actually hear it open all the way, dumping all at once. Then the boost would be gone until you hit a bump or something and gate would kick closed again. When you hit the loud pedal you never knew what you were going to get.

Not saying that's definitely your problem, but somewhere to look. In the case of the volvo, the wastegate actuator and such was very accessible at the back of the motor. Some testing with a hand pump (I modified our coolant pressure tester for actuator testing duty) revealed the sticky situation and a very unreliable opening and closing behavior with respect to applied pressure. A shot of WD-40 fixed it in the shop, but of course that burns off immediately. The fix required a new exhaust housing.

Seerlah
03-13-2012, 06:04 AM
The spring is located in the actuator. The boost pressure is what extends the rod, when the pressure is permitted into it via boost controller (ie n75).

I have a Forge WG I can let you have for $50 shipped. But the thing is I snapped the rod taking it off. It is threaded onto the Forge Motorsports actuator, so you would simply need to purchase the rod and you can use just some regular locking nuts for the flapper arm. And with the rod arm happens to be just a tad larger than the hole on the stock turbo (known thing). You need to bore the hole out just a tad bigger. No bid deal, though.

Aragorn
03-13-2012, 06:53 AM
It might be the flapper itself. Its welded to the end of the wastegate arm, and over time the bushing can become slack allowing the flapper to sit offcentre and often it will rattle around. Eventaully it will fall off and you'll end up with no boost.

Cant really tell without removing the turbo though.

zak
03-13-2012, 05:51 PM
Thanks for the replies. I have no rattling noises (but I do on my AEB Passat), so it appears to me that the issue is more likely in the actual wastegate flapper linkage rather than the actuator.

I have a line on a decent-priced used K03 that I will swap in. Maybe I will do a rebuild beforehand.

Will later engine code K03 turbos bolt on with no issues to the AEB? Can't see why they wouldn't, but then again........

Avant Nate
03-13-2012, 08:15 PM
Yes will bolt on no problem, it can even be considered an upgrade.

zak
03-14-2012, 05:07 PM
Thanks.