Oil catch tank

[Lazy-Ferret]

hmmm i was hoping to get rid of the blow by valve all together

Why do you want to get rid of it?

 

[R1cho]

Why do you want to get rid of it?

because it keeps clogging up

 

[Lazy-Ferret]

because it keeps clogging up

What is it clogging up with? Surely, if it is clogging, then an oil catch tank would not do a lot, as that would clog too?

Mine is always running in oil, so sort of continually flushing it's self through, but so much oil was coming through before I fitted the catch tank, that it could not stop it all, and a huge amount was therefore being carried through with the blowby fumes down into the turbo.

 

[Sweety]

That's why you fit the catch tank any oil the BBV chucks out towards the the induction gets caught in the tank & the tank will have a drain on the bottom so you can empty it out. I did look at taking the BBV off & it could be done I think but you would need a catch tank with an out put on the bottom which you could poss add to the one you've just bought (replace the drain screw) but you would also need to sleeve a pipe inside one of the top fittings to almost to the bottom of the tank (on the vent pipe from rocker cover) & leave the other fitting as it is but not sure if it would work or just act like you faulty BBV:nenau might be worth a try

 

[Lazy-Ferret]

That's why you fit the catch tank any oil the BBV chucks out towards the the induction gets caught in the tank & the tank will have a drain on the bottom so you can empty it out. I did look at taking the BBV off & it could be done I think but you would need a catch tank with an out put on the bottom which you could poss add to the one you've just bought (replace the drain screw) but you would also need to sleeve a pipe inside one of the top fittings to almost to the bottom of the tank (on the vent pipe from rocker cover) & leave the other fitting as it is but not sure if it would work or just act like you faulty BBV:nenau might be worth a try

That is how I said I do it on my car, and it works well... The catch tank I purchased already had a drain at the bottom designed for the pipe to go onto to drain it back into the sump.. The only thing I found was, the inlet and outlet pipes come in at an angle, and have a short dividing wall between them, but some oil still got through. Once I added the wirewool though, that all but stopped it.

 

[R1cho]

the blow by valve is basically just an oil catch can so why not just replace it with something bigger that is less likely to have the oil issue?

 

[Lazy-Ferret]

the blow by valve is basically just an oil catch can so why not just replace it with something bigger that is less likely to have the oil issue?

I am just trying to help you short cut the experimenting loop, as I spent the first 6 to 8 months of owning my car trying to get to the bottom of why it was drinking engine oil, and this is what I found fixed it for me. Not only that, the BBCV has a fairly important job, it is there to stop the turbo trying to suck the oil straight out of the engine when it is working flat out. Not only that, but with a pipe straight down to the sump, acting as a straw, it will also help to stop the potential "Diesel runaway" should you over fill it, or drive the car on an angle where the oil sloshes against that side of the engine.

There are really only 3 reasons the BBCV on there is not doing it's job already...

Firstly, the point that allows the oil to drain back into the engine it is blocked up... from my experience, these valves are so simple, and have so much oil passing through them, they do not normally block up, and a simple "Blow test", by blowing into the input, and seeing if air comes out the rocker cover, soon checks if either the valve or pipe back to the sump are blocked.

Secondly, if the valve inside the BBCV, that is supposed to close when the turbo is sucking harder than the pressure created in the crank case, is kaput. I took my first one apart, and had a look at it to see what was wrong. They are so simple, there are only two things that could go wrong in there, either the diaphragm has perished (Mine was still perfect, despite being original and full of oil), or the little hole under the lip of the BBCV that allows air behind the diaphragm to move in and out, is blocked. I thought that may have been the problem on mine, but after fixing it back together, and making sure the hole was clear, I still had the same issues.

Thirdly, and I think most likely, as it was the case on my car, it was not the original valve at all, and it is in fact the crank case has a higher pressure than it really should, because of engine wear. This has two negative effects on the BBCV, firstly, with this added pressure, and the suck from the turbo, the fumes plus oil splashes from the rockers etc, are being sucked through with the extra pressure, and before they get a chance to touch the sides of the BBCV, and are getting pushed/sucked straight down into the turbo. Secondly, the excess pressure is also coming up the pipe that the excess oil is supposed to drain down, also helping to push it on it's way to the turbo.

By fitting an oil catch tank between the engine and the BBCV, you have a reservoir to catch the oil before the BBCV, which can then drain when the engine pressure is low, but has enough capacity to hold the oil when the pressure is high. As I mentioned before, adding wirewool really added to how much oil it removed from the blowby fumes as well. The good thing is, doing it this way, you still have the BBCV as both a safety, plus a second point to catch oil.