Blow-by Control Valve

[lacroupade]

If you have oil either side of your intercooler this might be of interest......

For the unititiated, the BBCV takes 'fumes' (which will include varying amounts of oil depending how hard you drive your truck:augie) out of the rocker cover and allegedly splits out the oil for recirulation back into the sump, while the fumes are pumped into the air intake just after the MAF but before the turbo. In practice, a fair amount of oil does seem to find its way past the valve back into the air inlet.

Now then, I like to thrash my little darlings, so I'm getting oil evidence on both of the i/c hoses which tells me two things, (i) the engine has potentially been overfilled a bit, and (ii) the hoses probably need changing....if they leak oil then they leak air......:doh Mind you its also possible that the actual valve spring is stuck open or weakened as the air pressure doesn't seem that great, at least on tickover where its barely detectable.

BUT, in the process I'd like to remove this crappy source of contamination, so, am I right in thinking that I can take off the 3/4" ID pipe to the air inlet and blank it off with a solid plug of some kind (i.e. not a piece of bodge than could get sucked into the inlet/turbo )?

Then, either fit an oil catch tank of some kind or connect the pipe from the rocker cover down to the sump pipe (but I'm assuming the latter may not be desirable because there is an albeit very small amount of positive air pressure created that may stop the rocker cover from ventilating.....which begs the question (and I haven't researched oil catch tanks) how do you otherwise release that pressure?

On the Micra you can get a small filter to fit to the end of the rocker cover breather pipe that otherwise connects to the air filter box but not sure whats required on the old T2.

BUT - after all that, I'm also wondering if that oil doesn't have a useful function in providing a bit of extra lube to the turbo...so its a balance between having shitty air pumped into your engine along with clean stuff and any trade-off regarding said lubrication.........any advice/experience welcome! :bow

 

[makeitfit]

The turbo needs no extra crap oil thrown at the poor thing and neither does your intercooler need oil inside it. Both are detrimental to their prime function.
Cheap way out, well mine anyway , is to take off the oil pipe from the inlet hose and put it into a bottle or something to physically "catch" the oil. Blank off the hole in the intake obviously.
If you buy a catch tank of tinternet then it will still connect to the air intake for a bit of suck but will not put the oil back ion the engine:thumbs
Mines been off for a while and simply goes into an old water bottle

 

[lacroupade]

The turbo needs no extra crap oil thrown at the poor thing and neither does your intercooler need oil inside it. Both are detrimental to their prime function.
Cheap way out, well mine anyway , is to take off the oil pipe from the inlet hose and put it into a bottle or something to physically "catch" the oil. Blank off the hole in the intake obviously.
If you buy a catch tank of tinternet then it will still connect to the air intake for a bit of suck but will not put the oil back ion the engine:thumbs
Mines been off for a while and simply goes into an old water bottle

How does it handle back pressure from the rocker cover though, cos theres clearly enough at revs to blow oil through.....?

And I'm puzzled how a kosher catch tank can trap oil when the POS BBCV can't.....oh I forgot, its got 'Nissan' stamped on it :doh

 

[rayf3262]

How does it handle back pressure from the rocker cover though, cos theres clearly enough at revs to blow oil through.....?

And I'm puzzled how a kosher catch tank can trap oil when the POS BBCV can't.....oh I forgot, its got 'Nissan' stamped on it :doh

Have a mooch on the Patrol forum, there was some info on making an oil catcher from everyday bits and pieces...

Something along the lines of a Dyson vacuum cleaner (cyclonic?)

 

[lacroupade]

Have a mooch on the Patrol forum, there was some info on making an oil catcher from everyday bits and pieces...

Something along the lines of a Dyson vacuum cleaner (cyclonic?)

Not sure if theres room for one of those under the bonnet......:lol:lol:lol:lol

 

[rayf3262]

Its on page 35 of the ZD30 Y61 reference document.
"Oil Catch Can - How To Make Your Own & Install"

 

[rayf3262]

Not sure if theres room for one of those under the bonnet......:lol:lol:lol:lol

According to the latest TV commercial they are now available in:
Small, Medium & Large!

 

[lacroupade]

LOL! thanks for the linky

 

[lacroupade]

No obvious links for intercooler hosiery until I found this linky .... flipping allsorts and sizes and very cheap! :thumb2

 

[(RIP) PLANK]

does this control valve ever go wrong? and if it does what are the symptoms?

 

[lacroupade]

does this control valve ever go wrong? and if it does what are the symptoms?

Well its just a spring loaded valve that allegedly dumps the dirty air from the rocker cover AFTER its let any oil (always present in vapour form) leak down into the container and thence the sump. But if oil is getting past then it will probably blow from the intercooler rubber pipes, which is why I'm going to replace mine from the linky and dump the breather.

 

[(RIP) PLANK]

As i was advised by the intercooler repair people, since my intercooler leak has been sorted my oil consumption issue is cured :nenau

it does seem odd I agree, i was wondering if this caused the turbo pressure to do strange things with this valve?

 

[(RIP) PLANK]

another thought (yes my brain hurts now)

if this valve was stuck open, could the turbo pressure be directed into the top of the rocker cover and pressurise the sump if you look at the cut away diagram it seems a pretty direct route), thereby causing excessive oil consumption?

When i replaced the IC i did give this valve a good clean out, so maybe the oil contamination stops them working properly? :nenau

 

[lacroupade]

As i was advised by the intercooler repair people, since my intercooler leak has been sorted my oil consumption issue is cured :nenau

it does seem odd I agree, i was wondering if this caused the turbo pressure to do strange things with this valve?

shouldn't do because the valve blows oil-laden rocker cover vapour into the air inlet after the MAF but before the turbo.....theres always hot oil vapour in the rocker cover or the rockers wouldn't be being lubricated would they, so I'd say its either the valve failing open and letting ALL the shite through, or as you had, leakage of some kind in the i/c system or 'hosiery'.....

 

[(RIP) PLANK]

shouldn't do because the valve blows oil-laden rocker cover vapour into the air inlet after the MAF but before the turbo.....theres always hot oil vapour in the rocker cover or the rockers wouldn't be being lubricated would they, so I'd say its either the valve failing open and letting ALL the shite through, or as you had, leakage of some kind in the i/c system or 'hosiery'.....

Just been outside having a look under the bonnet! you are right

anyway, mine was without a doubt caused by the the IC leaking as i had it pressure tested (and repaired once!) But the oil seemed to be out of that pipe, before the turbo and the turbo was as clean (oil free) as we expected it to be. I'm going to stop thinking about this now before i get a headache :doh