Modifying the Breather System on the XE
Last Updated: 19-04-03

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I have had two 2 litre 16v XE engines in my Astra now. The first one had been thrashed and abused, probably from day one. It smoked quite badly when given stick, and there was a lot of jerking which pointed to a lot of crankcase fumes and oil going through the breather system, into the throttlebody and finally being burnt in the cylinders.

My new engine is in fine condition, well looked after, low mileage and uses no oil. However, it still had an annoying jerking when slowing down (clutch up) at about 1500/2500 rpm which suggests fumes are passing from the crankcase to the camcover, and then into the throttlebody.
Why? - well, the fumes dont pass by the airmass meter like the intake air does, so there is 'unmetered' air entering the throttlebody which results in this jerking.
It is probably made worse by my improved air intake and exhaust systems, and makes the car very annoying to drive around town where slowing down for roundabouts and giveways results in jerking so I have to put the clutch down very early. This is not only affecting enjoyment and ride quality, but putting the clutch down early is resulting in increased use of the brakes and down hill is actually reducing my safety margins by having to coast.

But, fear not! - It is very easy to cure the problem on the XE, although I did it in stages.
The above image shows stage one. It only took about 10 minutes to finish the proceedure, but the results are dramatic - absolutely no more jerking! It was so enjoyable to drive the car after this simple modification had eliminated all of the jerking.

For the above Modification you will need: Small Breather filter (i.e. K+N like this one), 2 extra hose clips, large plug or bolt to block the hose to the throttlebody, union to attach filter to hose, knife - total cost around £18.

Note: At the same time I drilled the plate inside the cam cover to allow more air through the plate from the main crankcase breather hose, but as the proceedure focuses on stopping unmetered fumes from entering the throttlebody I have omitted this proceedure.

1) Undo the larger of the two breather hoses at the rear drivers side of the cam cover by slackening the clip and pulling off the hose.

2) Cut the hose in half as shown in the above image.

3) Plug the end of the hose that leads to the throttlebody with a large bolt. Make sure the bolt has a large washer so it wont be 'sucked' in, and tighten a hose clip around the end of the hose to hold the bolt/cap in tight.

4) With the cam cover end of the hose, add an appropriate union to the breather filter with a hose clip, and attach the breather filter to the end of the hose, and angle appropriately - see images.

5) Make sure everything is tight and wont be sucked or blown off. - Enjoy jerkfree motoring.

Stage 2

Even on a healthy engine some oil is also blown through the breather system, so it is possible for the breather filter to become clogged up. For this reason in Stage 2 of the breather system modification I will add a catchtank which will be t-piece'd onto the above setup.
Finding a suitable catchtank for reasonable money hasnt been easy, but it would seem Forge Motorsport sell a suitable 2 litre one for reasonable money (under £80) so I will go for that - see the article soon!

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