Technical catch can connection question (not the same 'ole one)
04-28-2007, 11:43 AM
#1
Technical catch can connection question (not the same 'ole one)
Ok, I'd like some input from some guys that have catch cans to review my install and see if I did anything wrong or if what I'm experiencing is normal and just a side-effect of the install...
Here's my install, for reference:
https://my350z.com/forum/engine-drivetrain-and-forced-induction-diy/264910-diy-greddy-old-style-catch-can-install.html
I'm experiencing a minor high pitched whine while the engine is running and a sound like a squealing deflating baloon when I turn the engine off. The engine normally makes a winding down sucking noise when turned off, but this is a distinct addition to that, which seems to be coming from the rear of the engine, somewhere and disappears when I bypass my catch can setup, so it's deffinitely due to the can.
The sound is also absent if I disconnect the breather tube from the driver's side (that normally goes to the underside of the intake tube) from the catch can setup, so I've narrowed it down to that connection.
There is NO vacuum leak. I've checked all the connections (I know a few of them are a little ghetto and just sealed with RTV, but they are all sound) and the engine runs and idles just fine.
Therefore, I attribute the sound to the passage of air over or through something from where that breather tube comes from at the rear of the engine while under vacuum and as the vacuum system equalized with atmosphere when the engine is turned off. This is eather due to some resonance created by the addition of tubing to the system (maybe the step down in hose size from the 5/8" breather tube to the 3/8" catch can tube?), or that the amount of vacuum placed on the breather tube is different when connected to the catch can system than it is when connected to the intake tube.
My question is: Is this ok?
Is the ammount of vacuum on that breather hose different when it's hooked into the vacuum line of the PCV valve at the catch can than it is when connected to the intake tube? If so, will this connection cause any harm? Should I omit the breather tube from the catch can setup and reconnect it the the intake tube, or will it be fine as-is and I just live with the funky noise at shutdown (the little extra whine while the engine is running doesn't bother me and can't be heard from inside)?
Any insight would be appreciated.
Here's my install, for reference:
https://my350z.com/forum/engine-drivetrain-and-forced-induction-diy/264910-diy-greddy-old-style-catch-can-install.html
I'm experiencing a minor high pitched whine while the engine is running and a sound like a squealing deflating baloon when I turn the engine off. The engine normally makes a winding down sucking noise when turned off, but this is a distinct addition to that, which seems to be coming from the rear of the engine, somewhere and disappears when I bypass my catch can setup, so it's deffinitely due to the can.
The sound is also absent if I disconnect the breather tube from the driver's side (that normally goes to the underside of the intake tube) from the catch can setup, so I've narrowed it down to that connection.
There is NO vacuum leak. I've checked all the connections (I know a few of them are a little ghetto and just sealed with RTV, but they are all sound) and the engine runs and idles just fine.
Therefore, I attribute the sound to the passage of air over or through something from where that breather tube comes from at the rear of the engine while under vacuum and as the vacuum system equalized with atmosphere when the engine is turned off. This is eather due to some resonance created by the addition of tubing to the system (maybe the step down in hose size from the 5/8" breather tube to the 3/8" catch can tube?), or that the amount of vacuum placed on the breather tube is different when connected to the catch can system than it is when connected to the intake tube.
My question is: Is this ok?
Is the ammount of vacuum on that breather hose different when it's hooked into the vacuum line of the PCV valve at the catch can than it is when connected to the intake tube? If so, will this connection cause any harm? Should I omit the breather tube from the catch can setup and reconnect it the the intake tube, or will it be fine as-is and I just live with the funky noise at shutdown (the little extra whine while the engine is running doesn't bother me and can't be heard from inside)?
Any insight would be appreciated.
04-30-2007, 06:00 AM
#4
Monday bump. The real grease monkeys on this forum wake up yet?
If I can't figure something out soon, I might just omit the dr. side breather hose from the catch can setup and clean the TB once in a while; the noise is just pretty embarrasing at shutdown...
If I can't figure something out soon, I might just omit the dr. side breather hose from the catch can setup and clean the TB once in a while; the noise is just pretty embarrasing at shutdown...
04-30-2007, 07:24 AM
#6
The connections should be only to the PCV and to the lower plenum. Any other connection will cause an imbalance in the vacuum. If any of your hoses are not strong enough they will 'implode' and cause the RPM's to change. Make sure that your hoses are large and strong enough, and only connect to the PCV and the mani.
04-30-2007, 08:03 AM
#7
Thanks for the reply. My hoses are fine; I'm using stiff fuel line tubing. RPMs are fine as well. As for the connection, I know the PCV valve connection and the lower collector are standard, but I have also read about tapping in the hose that runs to the intake tube (this is also a PCV hose that comes from the rear of the left bank valve cover). Also, by all appearances, the new ARC can incorporates this line as well. Was just getting ready to PM Andy@performance about his...
As for an imbalance in the vacuum... what will this result in? I can see that since I stepped down the 15mm dr. side hose to 9mm to go into the catch can, which would speed up the air going into it, but the amount of vacuum should be the same regardless of where it's connected shouldn't it? I dunno. I see on the ARC can, it looks like it uses 15mm lines for all connections; not sure how that works, since the PCV valve and lower collector connection are much smaller than that. Regardless, I know I can tie in that dr. side line; I just can't figure out how to do it without it making funky noises on me. Otehrwise, it doesn't seem to have any negative effects...
As for an imbalance in the vacuum... what will this result in? I can see that since I stepped down the 15mm dr. side hose to 9mm to go into the catch can, which would speed up the air going into it, but the amount of vacuum should be the same regardless of where it's connected shouldn't it? I dunno. I see on the ARC can, it looks like it uses 15mm lines for all connections; not sure how that works, since the PCV valve and lower collector connection are much smaller than that. Regardless, I know I can tie in that dr. side line; I just can't figure out how to do it without it making funky noises on me. Otehrwise, it doesn't seem to have any negative effects...
Last edited by MustGoFastR; 04-30-2007 at 08:09 AM.
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04-30-2007, 08:49 AM
#8
Theoretically, if you wanted to have a correct catch can to prevent oil slude to enter the intake manifold you would bypass or catch the lines going from the drivers side valve cover to the botom of the intake tube.
The PCV on the passenger side feels vapor into the middle section of the lower manifold where it is drawn into the cylinders by small holes. These holes don't carry much oil or oil vapor therefore you won't have a big amount of oil in the catch can if you are N/A.
I bypassed the hose from the drivers side completely and the car ran perfect. I also have a carbing catch can on the other pcv valve and it worked great but didn't really have a purpose because N/A motors don't have a lot of blow by because of the low pressures.
The high pitched sound you hear is probably coming from the catch can because of the steel wool and how the air travels inside of it. Try opening it and changing the position of the steel wool. Also remember not to put too much or else it might actually drop vacuum pressure.
The PCV on the passenger side feels vapor into the middle section of the lower manifold where it is drawn into the cylinders by small holes. These holes don't carry much oil or oil vapor therefore you won't have a big amount of oil in the catch can if you are N/A.
I bypassed the hose from the drivers side completely and the car ran perfect. I also have a carbing catch can on the other pcv valve and it worked great but didn't really have a purpose because N/A motors don't have a lot of blow by because of the low pressures.
The high pitched sound you hear is probably coming from the catch can because of the steel wool and how the air travels inside of it. Try opening it and changing the position of the steel wool. Also remember not to put too much or else it might actually drop vacuum pressure.
04-30-2007, 09:10 AM
#9
I'm using a high-flow plastic filter medium inside the can, so I don't think that's a concern. Besides, I can distinctly hear the noise from the rear of the engine area and the noise is gone if I disconnect that dr. side tube from the catch can.
How did you bypass your dr. side hose? Where did you run it to?
How did you bypass your dr. side hose? Where did you run it to?
04-30-2007, 09:14 AM
#10
Originally Posted by MustGoFastR
I'm using a high-flow plastic filter medium inside the can, so I don't think that's a concern. Besides, I can distinctly hear the noise from the rear of the engine area and the noise is gone if I disconnect that dr. side tube from the catch can.
How did you bypass your dr. side hose? Where did you run it to?
How did you bypass your dr. side hose? Where did you run it to?
04-30-2007, 09:59 AM
#11
Ah, ok. No funky smells or residue or anything?
I'm just betting that hose is not normally under as much vacuum hooked up to the intake pipe as it is connected to the catch can in-line with the PCV valve line and it's the extra vacuum that is the cause of the wierd noises...
That doesn't explain how the new ARC can does it sucessfully, though...
I'm just betting that hose is not normally under as much vacuum hooked up to the intake pipe as it is connected to the catch can in-line with the PCV valve line and it's the extra vacuum that is the cause of the wierd noises...
That doesn't explain how the new ARC can does it sucessfully, though...
Last edited by MustGoFastR; 04-30-2007 at 10:09 AM.
04-30-2007, 10:23 AM
#13
Well, I'm pretty sure it's not that; It's hard to pinpoint the source of the sound, but it's distinctly more pronouced at the rear of the engine bay and my can is up front... Also, the sound is gone if I disconnect the dr. side hose from it and just run the can in the PCV loop.
04-30-2007, 10:53 AM
#14
The passenger side pcv has a stronger vacuum because it is connected right into the lower plenum where there is a constant vacuum.
The driver side however is after the TB which doesn't have as much vacuum until WOT.
BTW I didn't have residue from neither the drivers or passengers side. I couldn't smell anything either, I just had the stupid oil consumption crap on my 06'.
The driver side however is after the TB which doesn't have as much vacuum until WOT.
BTW I didn't have residue from neither the drivers or passengers side. I couldn't smell anything either, I just had the stupid oil consumption crap on my 06'.
04-30-2007, 11:06 AM
#15
Hmm, ok, I'll pull the dr. side hose from the can setup, then and either put it back on the intake tube or just let it vent to atmosphere (maybe stick a breather filter on the end of it, just for cleanliness' sake). I had very little residue on my throttle body, so it's not really a big deal to leave it hooked up.
Depending on the car, the pass side PCV loop CAN let quite a bit of oil by, as evedenced by others that have a can there, even NA. I had one of the DIY ones on my FX35 and it caught quite a bit of blow-by. When I swapped my plenum, there was a significant amount of oil reside on the lower plenum; this all comes from the pass side PCV loop.
Depending on the car, the pass side PCV loop CAN let quite a bit of oil by, as evedenced by others that have a can there, even NA. I had one of the DIY ones on my FX35 and it caught quite a bit of blow-by. When I swapped my plenum, there was a significant amount of oil reside on the lower plenum; this all comes from the pass side PCV loop.
04-30-2007, 11:13 AM
#16
Originally Posted by MustGoFastR
Hmm, ok, I'll pull the dr. side hose from the can setup, then and either put it back on the intake tube or just let it vent to atmosphere (maybe stick a breather filter on the end of it, just for cleanliness' sake). I had very little residue on my throttle body, so it's not really a big deal to leave it hooked up.
Depending on the car, the pass side PCV loop CAN let quite a bit of oil by, as evedenced by others that have a can there, even NA. I had one of the DIY ones on my FX35 and it caught quite a bit of blow-by. When I swapped my plenum, there was a significant amount of oil reside on the lower plenum; this all comes from the pass side PCV loop.
Depending on the car, the pass side PCV loop CAN let quite a bit of oil by, as evedenced by others that have a can there, even NA. I had one of the DIY ones on my FX35 and it caught quite a bit of blow-by. When I swapped my plenum, there was a significant amount of oil reside on the lower plenum; this all comes from the pass side PCV loop.
04-30-2007, 11:31 AM
#17
Right. However, I've never had any oil in the neck of the manifold and only a very slight residue on the throttle body, though; the majority of the blow-by comes from the pass side connection, hense people typically just putting a catch can there and leaving the dr. side alone. I was just trying to get everything in one shot for the cleanest system possible, but the noise is just to annoying, so I'll try something else.
If I can find a suitable, small can, I could use the same filter media in it and just put one of those little K&N breather filters on the outlet side. Prob overkill, but it'd be better than just letting the hose hang and vent to atmosphere unfiltered. Actually, I could probably just stick one of the DIY oil catches on there...
If I can find a suitable, small can, I could use the same filter media in it and just put one of those little K&N breather filters on the outlet side. Prob overkill, but it'd be better than just letting the hose hang and vent to atmosphere unfiltered. Actually, I could probably just stick one of the DIY oil catches on there...
04-30-2007, 11:41 AM
#18
Originally Posted by MustGoFastR
Right. However, I've never had any oil in the neck of the manifold and only a very slight residue on the throttle body, though; the majority of the blow-by comes from the pass side connection, hense people typically just putting a catch can there and leaving the dr. side alone. I was just trying to get everything in one shot for the cleanest system possible, but the noise is just to annoying, so I'll try something else.
If I can find a suitable, small can, I could use the same filter media in it and just put one of those little K&N breather filters on the outlet side. Prob overkill, but it'd be better than just letting the hose hang and vent to atmosphere unfiltered. Actually, I could probably just stick one of the DIY oil catches on there...
If I can find a suitable, small can, I could use the same filter media in it and just put one of those little K&N breather filters on the outlet side. Prob overkill, but it'd be better than just letting the hose hang and vent to atmosphere unfiltered. Actually, I could probably just stick one of the DIY oil catches on there...
