Just a quick note to the admin - I did try to post this in the how-to section but it wouldn't let me. Feel free to move it if you wish.
Although opinions will be split on whether this is the way to go when it comes to a noisy inlet manifold, I thought this guide would be helpful for anyone who wishes to follow in my steps.
I removed the internals from my manifold over 1000 miles ago and have experienced no problems since doing so. Although a small amount of torque is lost in theory, when it comes to day-to-day driving, this isn't noticeable and MPG has also remained unchanged. I did a lot of research before performing the mod and decided to remove my internals for two reasons:
1: A new inlet manifold with VIS is in excess of £500
2: Some people who have replaced them with new items, experienced the same problems again.
SORRY NOT ALL THE PICURES ARE GREAT QUALITY, I TOOK THEM ON MY IPHONW
I have a 2002 51 plate MG ZS 180 with 63.5K (62K ish when the problems started) on the clock.
After just a few weeks of ownership, it started to sound less like a V6 and more like a MK3 Fiesta in need of the tappets doing. It was also down on power. I read if you disconnected the VIS motors and you still have the problem the manifold is faulty. Another way to test this is to remove the front VIS motor, exposing the rod that opens and closes the butterfly valves, if this has any play it, chances are this is causing the rattling.
Firstly the tools I used (plus a star bit and phillips to take out VIS and undo manifold cover - not shown). I also applied some heat to the manifold to stop the plastic from cracking.
I removed the 10 screws from the cover.
Next I heated up my scraper and started from the corner, tapping it with a hammer until the seal broke. You have to hit it quite hard to break through the lip but once through the hard part is pretty much done.
By tucking one scraper behind the other and using a hammer, you can tap along the top seal to break it.
From here you can break the seal down each side about 1/2 inch as then the manifold curves and you have to start from the other side and repeat the process. Take your time with this as if you crack the cover it's game over! The manifold has to be air tight again once sealed.
Here is a picture of picture of the manifold without the cover on. You can see the rod attached to the 6 butterfly valves. This is what causes the problem. These valves are attached by a ball joint that wears out, as will be seen a few pics down.
You can remove these valves in two ways
1: Drill through the butterfly valve and remove just the valve, shown here:
2. Crack the valves where they join the manifold
I went for the easier option 2 this time, as I've done one of each, fitted both to my car and didn't notice a difference.
If you line the scraper up on the join (which can easily be seen but I couldn't get a clear picture of) one quick knock with the hammer will split it away.
Here is a close up of the ball joint
As you can see the ball joints have had it! The pic shows that only two of the four valves were connected on this one!
You then have to sand the lip down. A dremel is great for this, just to take the edge off and make it smooth ready for gluing. Picture shows pre sanding.
Once sanded, I cannot stress how important it is to thoroughly clean the manifold out, there will be bits of plastic all over the place and you do not want them getting sucked into the engine! I washed mine out with petrol and a brush, left to dry, then followed blowing it through with an air gun, double check every corner for shards of plastic.
Next put the cover back on with glue around the seal and tighten the ten screws. Depending on how cleanly the cover comes off, sometimes I melt excess plastic around the outside to seal any gaps - it's not pretty but it works. This cover came off fairly easily and didn't need extra plastic.
Glue wise I use Unibond plastic repair as it is heat resistant to 150C.
If anyone doesn't fancy trying to do this mod themselves send me a PM.
Hope this helps