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Sorry if this has already been asked and answered a thousand times, but what's the best way to free stuck exhaust valves?

I was thinking of spraying liberally with release oil and wd40 then trying to move them manually.

Anything to be wary of?

CheeRS

One of mine seized on the stock exhaust leading me to buy a Milltek - shame. People use 3 in 1 oil on the top where the linkage is, seems to help if you do it every month or so.

When they seize, and they will on stock, it's gods way of telling you to buy a Milltek.

I have come across 2 cars where they are stuck, they stick closed. Spent ages trying to coax them open but no joy. I suspect many are going the same way. Easy test is to check with engine off as both should be open. I think eventually the diAphragm fails and theres no fix.

I've never had mine seize but they started to squeak a year or so back and i applied son=me copper cote around the mechinisim and this has cured the squeak so i generally apply it every 3-4 months and never had the squeak back

Is this something that would be covered under audi warranty?

No - exhaust specifically excluded as considered to be a wear n tear item

pretty sure they have sintered bearings
grease might foul them up, collect dirt/grit and bind
hose them down good with a penetrating oil (PB Balster is one in the States)
just do this every couple of months, and use the sport button frequently

adsgreen wrote:No - exhaust specifically excluded as considered to be a wear n tear item

Ironic the variation between dealers and what is and isn't a warrantied item as I had my back boxes replaced when I had a warranty for squeeky valves. They had a couple of goes at lubing them up but when on the second occassion it didn't work they replaced.

I had a closer look yesterday and TBH I wasn't very impressed with the design.

I think ArthurPE is right about the sintering - the bottom bearing housing for want of better words, was actually disintegrating. I touched it with a screwdriver and bits fell off like it was a good chesire cheese.

Anyway, I was able to rotate the shafts and flaps OK using pliers on the protuding shaft. Didn't require much force to move them, but I could easily see that they have to be extremely freely rotating to work properly. The vacuum unit doesn't exert much force and is activated all the time to keep the valve closed except in sport mode where there is obviously a return spring inside the housing that pushes the flap open when the vaccum is stopped by the ECU.

I couldn't get the flaps free enough for the spring to be able to open them again when the sport button was pressed. If I opened them manually and started the car, then the right one would eventually close but not open again.

I think that there may have been a very thin bushing (brass or similar) between the shaft and the sintered housing that may have worn away meaning no more lubrification effect. My mate started panicking when bit started crumbling off so I didn't dissect any further

It felt like no matter how much I lubricated and rotated the shaft manually it just wasn't going to get any freer.

Anyway, in the end I forced the flaps open on both side, disconnected and blocked off the vacuum pipes so they stay open. At least it sounds good now - they were both stuck shut before and it made a noise like a 5HP outboard motor.

Sounds familiar. Mine also got stuck and there was no way of reactiviting them. Also unplugged them to be open all the time. I heard one might loose some low-torque but i don't know if that is correct.

tremmer wrote:Sounds familiar. Mine also got stuck and there was no way of reactiviting them. Also unplugged them to be open all the time. I heard one might loose some low-torque but i don't know if that is correct.

Its likely to be so marginal you wouldnt tell but you will lose power if you have not plugged up the vacuum hoses! If you havent thats an instant 30hp+ loss, actually anecdotally it may be closer to 60hp if mine was anything to go by when I had a small airleak!!

RSKiwi wrote:if you have not plugged up the vacuum hoses! If you havent thats an instant 30hp+ loss, actually anecdotally it may be closer to 60hp if mine was anything to go by when I had a small airleak!!

+1

Any vacuum leak has a big effect on power on the RS4, there's many valves on the engine that won't work properly if there's a vacuum leak. Never leave any vacuum line unplugged. Many of the early "carbon problems" were traced to leaking vacuum lines...

TimDogg wrote:One of mine seized on the stock exhaust leading me to buy a Milltek - shame. People use 3 in 1 oil on the top where the linkage is, seems to help if you do it every month or so.

When they seize, and they will on stock, it's gods way of telling you to buy a Milltek.

So do milltek ones not eventually seize up?

this reminded me to lube mine up...
used PB Blaster, basically a heavy penetrating oil that dispenses in a heavy stream
put some newspaper under them, and hit them outside and inside, liberally, then took it for a drive (was going somewhere any way) nice and quiet operation

the car sounds really good in sport mode

When I got my car I did check them and they were jammed solid.....You can empty dozen on cans of them and rotate them by hand it will still be stiff. Best thing to do is take a nylon or copper hammer and give a wack on the shank coming out at the bottom . DON'T go to hard as the collar welded to the exhaust tend to split easily . By hammering it a little you will brake the rust and your oil will get into it + it need to be loose so it can rotate freely. To check it work properly, take a rod and push the flap inside the exhaust. When finish put a liitle bit of wd40 .

Done it on my friend car as well recently . looks like they all have the same problem. By putting some lub on it a couple of time a year will keep it out of trouble.