This is the item you will be replacing, it is the top throttle breather pipe.
Part number is either 0003134 V008 0000 00 (updated to A1600180312) or 0018484 V002 000 00.
Below shows you the route of the pipe and the valve that can fail (circled).
The other end dips just down behind the engine...
...where it pushes on to the oil pump housing.
There is usually a crimped clip on the top part of the hose, these can be levered off.
With the clip off, the pipe can be twisted and pulled from the throttle body.
Reach down the side of the engine and twist and pull the other end. It can be tight.
If you have air conditioning, you will have even less space to work with.
Here you can see the new and old pipes together. They are identical
except the replacement has an extra hose clip (maybe necessary for a Roadster).
Push the ends of the new pipe in place. There is almost no possibilty that you will be able to reuse the old clip so a decent zip tie should be ok. Ideally you want a small jubilee clip (don't overtighten).
If for some reason you cannot get the old pipe off you can always attempt to replace just the valve. Pull the hoses off from each side of the valve and insert a new one.
Handmade Breather Pipe
Mister Bridger from the forum came up with a radical idea. Because he has air conditioning, replacing this breather is a much harder task. Originally Stuart thought about just changing the valve but found that it was hard to get off and thought that the pipe may split.
He decided to make his own breather pipe that would make it easier next time around.
Mister Bridger's Story
A trip to a plumbers merchant and for £1.41 i bought 1m of 10mm soft copper pipe.
On the way home I bought 1.5 m of Net curtain wire for £2.48 at Homebase. After taking
a look at the original, I bent the copper pipe as close to the original in shape as possible.
I cut the end going onto the valve a little shorter for 2 reasons.
I wanted to have some flexxing to be allowed at the join to the valve as it is very hard to get every angle spot on when bending the pipe by hand.
It makes it easier to pull the valve off when the time comes to change it.
Now for the easy bit. Make sure you change the valve before an oil change is due. Pull off the old valve. Squirt some brake cleaner fluid/carb cleaner/ or WD 40 down the pipe. Then insert the Net Curtain Wire and push it back and forth to move any crud. Give it a final squirt and all the fluid and crud goes into the sump and is sucked out with the old oil.
WARNING- make sure you do not loose the straw of whichever cleaner you
use down the pipe. A good tip is to apply a large bit of BLU TAK to the straw
and this will stop it going down the pipe.
Extra Info For Bending Copper Pipe
You have 4 ways to bend the copper pipe to the required shape.
Carefully bend it by hand - be careful as you can kink the pipe.
Pack the pipe with sand and hand bend it - be sure to clean the pipe out after.
Use a proper mandrel pipe bender - expensive if you can find the right size.
Use a pipe bending spring - if you can find one the right size.
If you have air conditioning, plan to keep your smart for a long time and don't fancy lowering the engine more than once, this is a good alternative. Once the DIY top
breather pipe has been installed in position, the valve can be swapped in minutes which tends to be the part that fails. Saving you from mucking about behind the A/C pipes again.
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