having lots of cooling problems lately had the metal water pipes on back of engine changed when sprung a leak, but now week or so later (maybe 100 miles) steam from under bonnet again, when filling rad and squeezing top hose can hear what sounds like a leak round no.2 clyinder so i was going to try a plenum bypass but more i read and see more confused i get.seen pics showing 3 hoses from back of engine to (i think ) the turbos and somewhere else( yes i am this lost) but have aslo seen and read that you can block the small pipes off and still be ok .as i'm not sure this is the cause of the leak just looking for a easyish way of testing to find out. cheers

It can be a confusing job to carry out. Have you had a look in the FAQ section? There is a FAQ in there that explains it well (I can't link to threads with my browser).

 

Do you mean the small pipes coming out of the throttle bodies? If so these are vacuum pipes (drivers side goes to EGR solenoid, pass to carbon canister) they can be blocked off when you are removing the EGR and CC.

HTH

The simple answer to what the bypass does:the water pipes under the plenum go to and return from the underside of the throttle bodies, so basically you are stopping the water feed, by redirecting the pipes away from the plenum to maintain a flow around the engine.

 

The 2 top little pipes that come from the rear of the plenum are no longer used, so you create a loop basically.

 

Daves pics:

 

In this pic you can do away with a long hose and the steel pipe and connect it to the pass turbo feed.

 

 

So the top 2 pipes that connected to the plenum now route directly to the turbos without the spagetti of pipwork