Need some help with boost leaks

[BlackHalo]

Is it normal to leak out the breather hose from the valve cover? Once i plug it on a leak test than oil leaks out of my oil cap. Also, was wondering if you pull out the dipstick than a bunch of a air shoots out... Should it be there or is it a leak. I searched but could not find any solid answers so.

One other problem my 1g bov kept leaking out the dump tube so i tried crushing it slightly and it still leaks but now.. i guess im getting compressor surge because when i shift it flutters. So, guess i over crushed it?

 

[psychlow]

Yep, you likely overcrushed it. You'll need a new one.

If pressurized air is entering your valve cover, you need a new PCV valve, or you need to do a PCV delete.

 

[BlackHalo]

So air isnt suppost to leak out of the breather hose that goes into the intake? I only start leaking out from the cap whe i plug that hose. So im guessing not. I'll look into a new pcv i guess.

 

[psychlow]

Correct. Air should not move from the intake tract to the valve cover.

 

[BlackHalo]

Well, i took the pcv valve off and cleaned it out. I blew some air through witha compressor and sometimes air would come out. But its a cheap part so i'll replace it tommorow. From searching i noticed that other people leaked air out of the breather hose. So, a pcv could fix it?

 

[oldman]

Well, i took the pcv valve off and cleaned it out. I blew some air through witha compressor and sometimes air would come out. But its a cheap part so i'll replace it tommorow. From searching i noticed that other people leaked air out of the breather hose. So, a pcv could fix it?

A functional pcv valve opens under vacumm to allow crank case pressure to be released. It's a one way street out of the valve cover.

 

[BlackHalo]

A functional pcv valve opens under vacumm to allow crank case pressure to be released. It's a one way street out of the valve cover.[/QUOTH

Heh, can you explain that to a newbie? So, it is normal to leak out the breather hose? And when it is plugged to do a leak tester, pressure should build up in the dipstick and oil cap?

 

[oldman]

A functional pcv valve opens under vacumm to allow crank case pressure to be released. It's a one way street out of the valve cover.[/QUOTH

Heh, can you explain that to a newbie? So, it is normal to leak out the breather hose? And when it is plugged to do a leak tester, pressure should build up in the dipstick and oil cap?

No it's not suppose to. You have a bad pcv valve which allows boost pressure to push it's way into the HEAD when under boost. "YOU NEED A NEW PCV VALVE" you newbie.

 

[BlackHalo]

Thanks for the help... i read up all day on performance and when something goes wrong i have no clue what to do... So, thanks for clearing that up

 

[psychlow]

Oh yeah - also - DON'T BOTHER WITH PARTS STORE PCV VALVES! Get an OEM valve from a dealer. I think maybe 1% of DSMers have had luck with part stores PCV valves. I'm included in the other 99%.

Also, BE VERY CAREFUL installing the PCV valve. Pretend the valve cover is plastic whenever you work on it, because it breaks just as easily.

 

[BlackHalo]

Installed a new oem pcv valve today and am still leaking out of the breather hose... Any other suggestions?

 

[psychlow]

What's your compression like? It's possible that if the PCV valve is fine, then you're actually leaking air past your rings and into the crankcase.

If this is the case, your BOV might not be overcrushed. It could just be that your engine isn't producing enough vacuum to open the valve fully.

 

[Darksyne]

Oh yeah - also - DON'T BOTHER WITH PARTS STORE PCV VALVES! Get an OEM valve from a dealer. I think maybe 1% of DSMers have had luck with part stores PCV valves. I'm included in the other 99%.

Even the Mitsubishi ones I have purchased leak under boost. My solution was to fabricate an air-tight catch can with the breather hose and PCV hose running into it. I then have a line going to the stock intake (vaccum all the time) to evacuate the crankcase gasses.

In the stock system, while in vaccum, air would be drawn from the intake, through the breather hose, through the PCV valve, and into the intake. While under boost, the PCV valve should seal and any pressure that builds up in the crankcase will be pulled into the intake.

With my modified system, gas evacuation isn't as efficient as the stock system at idle but is the same or better than the stock system while moving,

I fought with a PCV valve boost leak for the past year and tried three OEM PCV valves. This is how I solved my problem

 

[LowFourteen95]

I'm trying to figure out how air is getting into my crank case during a boost leak test also. It isn't coming in through my pcv, since that and my breather are both vented to a catch can. The port on the intake is then blocked off. The engine was just rebuilt by the previous owner last june, and doing a compression test gives me 180 psi average across the board, with all cylinders within 1 or 2 psi of each other. Basically, I can hear air coming out by my catch can, and out of the dipstick. Is it just leaking past the rings?

 

[BlackHalo]

I just did a compression test as well all all looks good there.. close to 180 on each cylinder. So, i guess i just need to figure out why im loosing boost out the breather hose.

 

[oldman]

I just did a compression test as well all all looks good there.. close to 180 on each cylinder. So, i guess i just need to figure out why im loosing boost out the breather hose.

I've just spoken to a friend who works at a dsm shop. He said the air will leak throught the rings although the compression test numbers are normal especially if the car is cold.( rings not expanded yet). How much pressure did you pump into the system?

 

[oldman]

Also, did you use oil when doing the compression test? If so, that will give you better numbers because it will help hide any ring problems. That's what my friend told me, someone correct me if I'm wrong.

 

[BlackHalo]

What do you mean how much air am i pushing through the lines on a boost leak test? I set the compressor at around 15 or so when i do one. But the first few times i did them i didnt change the psi on the air compressor and prob ran too much pressure through. But i dont know exactly what your asking. So try and do a boost leak test with the car at operating temp? I dont know...

Just saw your second post.. Yea thats a wet test and will bump the compression wayyy up. I did but when i did it shot my compression up to like 270.. but i was at 180 on all of them before i did that.

 

[DSM90AWD]

I have both the PCV (modified to free-flow) and VC breather venting to a catch can and find air escaping those routes when pressurizing my intake.

This is normal (as oldman said) due to the rings not sealing when cold (hence step #1 when doing a compression test is to warm the car up)

 

[DSM90AWD]

Just saw your second post.. Yea thats a wet test and will bump the compression wayyy up. I did but when i did it shot my compression up to like 270.. but i was at 180 on all of them before i did that.

holy crap.. how much oil did you put in there? a capfull is all that's needed.

 

[BlackHalo]

holy crap.. how much oil did you put in there? a capfull is all that's needed.

Just a capful :0 I might be a little high on my number.. but it was wayyy up there.

 

[BlackHalo]

I have both the PCV (modified to free-flow) and VC breather venting to a catch can and find air escaping those routes when pressurizing my intake.

This is normal (as oldman said) due to the rings not sealing when cold (hence step #1 when doing a compression test is to warm the car up)

So, how about doing a leak test when the car is at operating temp? I'll have to give that a try. My car boost fine(except for that i killed my bov)

 

[oldman]

What do you mean how much air am i pushing through the lines on a boost leak test? I set the compressor at around 15 or so when i do one. But the first few times i did them i didnt change the psi on the air compressor and prob ran too much pressure through. But i dont know exactly what your asking. So try and do a boost leak test with the car at operating temp? I dont know...

Just saw your second post.. Yea thats a wet test and will bump the compression wayyy up. I did but when i did it shot my compression up to like 270.. but i was at 180 on all of them before i did that.

I would do another boost leak and compression at operating temp and see what happens.

 

[oldman]

Damn it, oldman types too slooow.

 

[BlackHalo]

, yea.. thanks for the help i'll try another boost leak test at operating temp. Ive already done two compression tests today in between a couple hours at operating temp and ive been getting 180 across.. So, i know the compression is fine. But yea i'll try a leak test later on today at operating temp.