Hi,
This might explain it better.
Cleaning crankcase breather system on V6
11. Jul 2006 at 07:12 (c)2006 Ronald Mc Burger
This guide will save you the hassle of blown rocker gaskets. It is a preventative measure and I would suggest you do it when you first get the car and then every 12 months thereafter.
Sidestepping for a moment, the chain of events is basically this. If the oil is old and hasn't been changed regularly or for some time, it will be black coloured and this is where it all starts to go wrong. Of course, the car still runs beautifully, so you'll do that oil change next month won't you?
The problem is that oil serves many purposes and in this case it has soaked up lots of microscopic particles. During the normal running of the engine a 'mist' of oil is present in the crankcase, a bit like the water mist at Niagra falls. As the engine on the V6 is a sealed unit, crankcase ventilation is essential and thus the breather system. This mist is sucked up into the breather system and, over time, tiny deposits of crud start to build up until it reaches a critical point. You will not be aware of this because the car still runs and you can do that oil change the next month again!
At the point where the system becomes unable to cope with the demand for ventilation, the pressure in the crankcase builds up. It has to get out somewhere and always takes the weakest option, which on the V6 is the rocker gaskets. Once that escape occurs, you have gasket failure and thus the leak starts.
So, maybe now you see why this is so important. Oil changes are one of the cheapest preventative measures you can do, yet many people leave the oil for years as the car 'seems' fine.
Now that you understand the importance let me quickly run through the system that you will need to work on. Starting at the back of the engine, drivers side, is the crankcase breather box. Next to this is another small electrical box which is also part of the breather system. From the breather box are two tubes, one large and one small. From the electrical box is one small tube. The two small tubes connect to the plenum at the back. The bigger tube divides in to two and then both bigger tubes also join the plenum.
The black plastic box on top of the pleunum is actually in two parts. The cover, which has ECOTEC written on it, and the main body. Through a series of channels in the internal parts of this box means that the two bigger tubes are fed pre throttle and the two smaller tubes are fed post throttle. This means that you get higher negative pressure to vent the crankcase under throttle.
So to the cleaning. (at last).
FIRST OF ALL THE ENGINE MUST BE COLD!
This job will require the removal of the wipers & scuttle for better access to the plenum cables and breather box. While you are working there you will get a good view of the Heater Bypass Valve (HBV).
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Unclip and diconnect the 4 breather tubes on the back of the plenum. Remove the plenum and blank out the 6 intakes with paper towel in case of parts and dirt ingestion.
Remove the 4 TORX bolts and seperate the throttle chamber from the plenum.
Carefully prise off the ECOTEC cover, being careful not to prise the actual black breather box at the same time. This will reveal a hidden TORX bolt securing the black box to the plenum.
Remove the 3 breather tubes - 1 small one from the breather box, 1 large one that divides into two from the same breather box, and lastly the last small breather tube.
Starting with the Vent housing, the smaller pipe (brass) has a very small hole in the centre.
Picture shows housing off the car for clarity only. You do NOT remove this box!
Don't mistakenly think that the whole pipe should be clear, it shouldn't. It is just the little hole in the centre that needs clearing. Firstly, clean around that pipe with carb cleaner and a rag. Don't go mad with carb cleaner as it is highly flamable (hence cold engine). Clean the pipe to get rid of any crud and you will now see the hole. Using a stiff wire and a small squirt of carb cleaner, push the wire about 4" into the hole and give it a good wiggle around. A very quick squirt of carb cleaner to finish.
Next, the big pipe.
Scoop out as much crud as you can with a screwdriver or similar. Try not to push the crud back into the box if you can. When you have done this use a rag and carb cleaner to wipe the inside and outside of that pipe. DO NOT squirt tons of carb cleaner inside unless you are immediately doing an oil change. Car cleaner is not good inside the crankcase as it eats seals! Don't believe me? Squirt some on to your latex gloves and watch what happens.
Next, the electrical box pipe needs the quickest of squirts and a wipe, also a gentle poke with that wire, but DO NOT force the wire in, there is a seal inside and you may puncture it.
Now move onto the 3 tubes. Use as much carb cleaner as you like now, but away from the car. Clean and clean again. They need to be totally clear. The bigger 'Y' tube fits nicely onto a garden tap to get a final blast through. Don't cut corners, this is where most of the crud will be, in that bigger tube at the top.
Black breather box needs tons of carb cleaner and some gentle prodding with the stiff wire. You should be able to blow through all 4 pipes when cleaned and you should meet no resistance.
The plenum needs general cleaning inside with carb cleaner, but most importantly around the round recess near the front where the black breather box feeds its two smaller tubes to.
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