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Pvc Valve - Too Much Pressure In Crankcase


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  • It's not a MKI!
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Mate, no offence, but it doesn't sound like you're too mechanically savy.

You should take it to a mechanic and fill them in on the details and get it diagnosed properly.

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If the catch can or hoses have a blockage it may not be allowing the pressure to release? Have you tried returning the setup to stock to see if it still happens? ps. ROCKER not ROCKET cover dude! :blush:

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  • Member For: 21y 5m 20d
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The holes vary from engine to engine. In the N/a six as shown in your pic its the middle one that leads to the inlet that is the one you would need to enlarge. Sorry, I thought that might throw you off after I posted but did not have time to correct. At least it shows you read the post. I can show you a picture on a E series engine and the principle is the same on all engines.

To explain, there is a 1 inch tube welded to the rear of the rocker cover. This then leads to an oil catch can. In this case that long tube has baffles,tubes and stainless steel mesh to catch blowby oil under load. On the end of it is a filter but you can have a hose leading back to the inlet to comply with emissions. The tube is located where it is so that upon shutdown the oil collected drains back into the engine.

Also on the PVC side I have another metal catchcan located under the manifold to catch any oil when cruising.

This is all done to keep oil out of the inlet track and minimise any detonation on high boost.

In your case you are worried about the dipstick blowing out so you need to address the nonpcv side if you want it to stop blowing. It also helps minimise engine oil leaks also.

post-822-0-87645900-1297933375_thumb.jpg

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  • Member For: 14y 8m 8d

Mate, no offence, but it doesn't sound like you're too mechanically savy.

You should take it to a mechanic and fill them in on the details and get it diagnosed properly.

well its definitely learning curve, this was my first turbo conversion in my backyard. for a 22 year old that works as an office bitch I reckon I did orite installing a turbo/stage 2 cams on my falcon. yet the simplest things always confuse me sigh*

who knows if it'll blow up but that's what u guys are here for ! =)

Hawlass - have checked all hoses for blockage and nothing returned it to stock got some blow by in it a little bit only but the intake was very oily most likely from the vapors itself.

ian -im in nsw/sydney.

Turbotran - ahhh now I understand completely thanks for taking the time to clarify it further for me. I'll just use your idea and weld up a larger pipe on it and hose it to the catch can with baffle then back to the inlet. so im just really increasing the diametre of the pipe so it releases more pressure. thinks I got it... not sure how ill go with welding a pipe there.. im useful with a mig as far as fences go but ill give it a shot.... thanks for the explanation. if I had no ideas I was going to stick a 12v electric crankcase pump or something from the us and use that to vacumn the fumes and then vent it. stupid idea but luckily this one came up... once again thanks

should I still check the compression of the vehicle and do leak down tests ?

Edited by zayd687
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you still have something else wrong if you need to do this to get rid of the pressure.I was running 18 psi and necer had an issue with this.

I would be do a leak down test and compression test before you go any further.

Find a local mechanic and get them to do the tests for you.

Ian

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  • Member For: 21y 5m 20d
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Do a compression test or/and leak down would be advisable as you could have a broken ring or/and ring land and that should show that up. An irregular idle would indicate that also.

Take off the PCV valve out of the rocker cover whilst the engine is running and if the engine fumes alot that is another indicator of ring wear. But personally have found a high blowby engine not to be too detrimental on power or even fuel economy contrary to what many believe.

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  • Member For: 17y 8m 5d
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Don't know if aanyone mentioned this, but if you have hoses from rocker (not rocket) cover

And if they don't have the oneway valve the boost pressure will pressurise the crankcase.

With boosted cars the only time you see vacuum is off throttle.

You need to check your hoses for correct hook up.

If it's right and you are still getting excess pressure, then I would say a leak down will confirm either ring or piston problem.

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  • Member For: 14y 8m 8d

Don't know if aanyone mentioned this, but if you have hoses from rocker (not rocket) cover

And if they don't have the oneway valve the boost pressure will pressurise the crankcase.

With boosted cars the only time you see vacuum is off throttle.

You need to check your hoses for correct hook up.

If it's right and you are still getting excess pressure, then I would say a leak down will confirm either ring or piston problem.

can this happen to the air breather?

the one way valve ( pvc valve ) is at the back of the rocker cover. there is no one way valve on the breather which has hoses connecting to the catchcan.

so just for query upon WOT... the air breather is pulling in air into the crankcase?. so if you have a venting catch can... would the rocker cover air breather still be pulling in pressure in to the crankcase?

I'll check by removing the pvc tonite, I changed the pvc yesterday too. theres no smoke at all rpm ranges so hopefully not piston, I have a mate working at toyota who's going to perform the tests... I'll get back to you guys on what the results are.

I also put a better rubber on the o ring of the dip stick, hasnt popped out so far.. but I haven't gone past 4000 rpm....

much appreciated for your guys responses.

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  • RUS531
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It may have been said earlier but, the hose that connects between the Pcv and the plenum has a second one way valve installed. Might pay to check if there is one installed and if there is, replace it

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