Do I Need A Catch Can?

[V28VX37]

On 14/11/2007 at 3:16 PM, Dose Pipe Sutututu said:

IMO I believe they are worth fitting... it keeps your plenum nice and clean, no matter how new a motor a small amount of the oil will evapourate.

Thread revival time.

I'm getting a drop of oil under my comp cover and I reckon it's due to blow by, so a catch can is probably the go.

eBay is mental with options so I thought I'd tap into the hive mind – any recommendations?
I think what I need is the following:

• Decent capacity 300-500ml
• Cylinder shape, max 9cm diameter x 20cm height (installing next to the battery in the R34 bay) 
• Some way of checking how much oil is in there
• Perhaps internal filter
• Some baffling but not too much
• Preferably openable
• Big enough fittings to suit factory diameter hose (16mm hose ID)
• No atmo venting
• Decent quality, no leaks
• Aus stock

Here's a bit of a shortlist of what I've found:

$35.99 - cheapest 'D1 spec' style but no baffles, plus a bad review

$76.80 – seems like nice design but small volume, prob 200-300ml?

$79.00 – good design with internal filter, however 19mm fittings a bit too big, and no tank to speak of?

 

Thanks guys.

Also here's a pic of the oil collecting:

[KiwiRS4T]

18 minutes ago, V28VX37 said:

Thread revival time.

I'm getting a drop of oil under my comp cover and I reckon it's due to blow by, so a catch can is probably the go.

eBay is mental with options so I thought I'd tap into the hive mind – any recommendations?
I think what I need is the following:

• Decent capacity 300-500ml
• Decent capacity is 2Litres
• Cylinder shape, max 9cm diameter x 20cm height (installing next to the battery in the R34 bay) 
• Some way of checking how much oil is in there
• Sight glass (usually plastic) or removable top would do it.
• Perhaps internal filter
• Some baffling but not too much
• Either or both (never seen too much!)
• Preferably openable
• Big enough fittings to suit factory diameter hose (16mm hose ID)
• Heat resistant oil resistant rubber hose is fine (or braided for bling factor)
• No atmo venting
• Yep hose to intake is the story
• Decent quality, no leaks
• Aus stock
• You'll probably end up getting something fabricated - most ebay ones are cr*p

 

 

 

[Kinkstaah]

I bought a Mishimoto. It does not have 2L Capacity though, but after a beating with the oil mods I don't need 2L Capacity so thats nice!

 

However it DOES have a filter, and DOES fit near the R34 battery and DOES have baffling and DOES cost nearly $400 oh shit.
If you're getting oil *there* then I would be checking your intake pipes.

I had oil all over my intake pipes, it was literally pooling in the crossover pipe. Not once did I have a drop where the picture is.

[V28VX37]

I bought a Mishimoto. It does not have 2L Capacity though, but after a beating with the oil mods I don't need 2L Capacity so thats nice!
 
However it DOES have a filter, and DOES fit near the R34 battery and DOES have baffling and DOES cost nearly $400 oh shit.
If you're getting oil *there* then I would be checking your intake pipes.
I had oil all over my intake pipes, it was literally pooling in the crossover pipe. Not once did I have a drop where the picture is.

Thanks Greg, good info. Though no way am I paying $400 for a catch can lol - my approach is to go the cheap option first, try to patch it up, and only then pay the full price for the thing I should have bought in the first place

I saw the photo of your crossover pipe, that was a lot of oil. I'm not sure how that much oil could make it though the intercooler without leaving a trace at the comp cover though? Maybe your front housing is structured differently to the SS2?

[Kinkstaah]

I also had a hypergear turbo prior to that, but in any case it's going to be oil dumped into the intake. It may simply be that your comp cover isn't as sealed as it should be and it's coming out there instead of later on in the piping. I'd still pull off some of the piping (didn't you do this recently? Was there any oil in that piping?)

Thing about cheap catch cans is they don't actually catch anything.
But yes I had all that oil and nothing in the comp cover, which makes me think the issue is kind of in the comp cover, because all that oil had to be going through the compressor and, well, it certainly did not leak.

Oil catch cans are still useful as a diagnostic anyway, or can be. But it needs mesh, needs filter, and needs baffling which nearly none of the items have, they're all almost empty cans from when I did research recently on the subject.

[V28VX37]

1 hour ago, Kinkstaah said:

I also had a hypergear turbo prior to that, but in any case it's going to be oil dumped into the intake. It may simply be that your comp cover isn't as sealed as it should be and it's coming out there instead of later on in the piping. I'd still pull off some of the piping (didn't you do this recently? Was there any oil in that piping?)

Thing about cheap catch cans is they don't actually catch anything.
But yes I had all that oil and nothing in the comp cover, which makes me think the issue is kind of in the comp cover, because all that oil had to be going through the compressor and, well, it certainly did not leak.

Oil catch cans are still useful as a diagnostic anyway, or can be. But it needs mesh, needs filter, and needs baffling which nearly none of the items have, they're all almost empty cans from when I did research recently on the subject.

Fair points. Yes I had most of the intake piping off the other week to replace intercooler-to-crossover rubber joiner. I couldn't see much residue in the plumbing or the crossover pipe. This said I didn't pull off Scotty's intake pipe or the silicone expander going into the turbo intake - I'd imagine having some oil on these parts if it's from the breather.

Re catch can as a diagnostic too, that's exactly what I want it for. Rather than pulling the breather-to-intake hose and venting into atmo, it'd be good to have something there to confirm if that's where the oil is coming from. I hope it's not an issue with the comp cover, I'd really hate to pull off the turbo since it was just off for the HG replacement...

This is the type of catch can I ordered (second on the list above), it still seems to do 'something' without any additional baffling or filtering (and can be improved if need be):

 

[KiwiRS4T]

5 hours ago, V28VX37 said:

 

This is the type of catch can I ordered (second on the list above), it still seems to do 'something' without any additional baffling or filtering (and can be improved if need be):

 

Do you know where the second hose goes to? You say it does "something". Yes it catches some liquid but depending on where the outlet goes there could have been a lot more oil/water vapour pass through it. The point of the baffles is to try to get all or most of the residue to deposit in the can and not pass through as vapour.

[V28VX37]

22 minutes ago, KiwiRS4T said:

Do you know where the second hose goes to? You say it does "something". Yes it catches some liquid but depending on where the outlet goes there could have been a lot more oil/water vapour pass through it. The point of the baffles is to try to get all or most of the residue to deposit in the can and not pass through as vapour.

Yeah totally. The first test will be to determine whether 1) there's something in the catch can and 2) whether that clear up the drop of oil at the comp housing. If both are true good, if 1 = true but 2 = false, I'll look at adding some baffling

Here's some decent looking guides for adding baffling and filter media: http://forum.grrrr8.net/showthread.php?t=38308 & http://www.evolutionm.net/forums/evo-how-tos-installations/485682-how-another-diy-catch-can-mod-dual-baffles-extended-inlet-tube.html

I'm surprised that eBay selection is so crappy, even the more expensive ones advertised as 'baffled' almost never show the internals to see if they actually are.

[Kinkstaah]

Because they aren't ;).

There's a reason the Mishimoto and RIPS and other higher costs ones cost higher costs, the way I looked at it (I had a basic one initially) is I kind of want the item to perform its intended function. A catch can catching 20% of the stuff going through that is a pretty crap catch can at when it comes to catching things in the can.

You *could* be massively dodgy and just run a hose from where you currently have it into something temporarily to see if it clears your oil up. But it's a strange place for oil to be accumulating in any case given it's not anywhere else in the system. Oil coming out of the compressor cover isn't usually what leads people to think they have a problem with blowby and want to catch it in a can.

[Dose Pipe Sutututu]

A baffled catch can is the best option however if you're a tight skyline owner like myself a basic catch can with steel wool stuffed into it will also do the trick.

If you want, delete the PCV as well, block it plenum side and put a bung on the side of the cam cover. Then just run the breather hose from cam cover to catch can, then catch can to intake.

[V28VX37]

Because they aren't .
There's a reason the Mishimoto and RIPS and other higher costs ones cost higher costs, the way I looked at it (I had a basic one initially) is I kind of want the item to perform its intended function. A catch can catching 20% of the stuff going through that is a pretty crap catch can at when it comes to catching things in the can.
You *could* be massively dodgy and just run a hose from where you currently have it into something temporarily to see if it clears your oil up. But it's a strange place for oil to be accumulating in any case given it's not anywhere else in the system. Oil coming out of the compressor cover isn't usually what leads people to think they have a problem with blowby and want to catch it in a can.

Haha, yes.

Re blowby, I'm following Tao's recommendation here, he suggested the oil is likely coming from the breather. We'll see.

[V28VX37]

9 hours ago, Dose Pipe Sutututu said:

A baffled catch can is the best option however if you're a tight skyline owner like myself a basic catch can with steel wool stuffed into it will also do the trick.

If you want, delete the PCV as well, block it plenum side and put a bung on the side of the cam cover. Then just run the breather hose from cam cover to catch can, then catch can to intake.

Cheers mate. Some people have modded this type of catch can by placing stainless steel scrubber pad inside the baffle/coalescing chamber of the unit:

^^^ I'm not convinced that that's the right place though, most sources seem to suggest that the steel wool/scrubber should be at the bottom of the can, with a cross-drilled pipe running from the dirty side to the bottom, like this:

[MrStabby]

12 hours ago, Dose Pipe Sutututu said:

If you want, delete the PCV as well, block it plenum side and put a bung on the side of the cam cover. Then just run the breather hose from cam cover to catch can, then catch can to intake.

Yeah what's even the point of the PCV? Dont the oil drains provide a path from the crankcase to the cam covers, and there's no PCV on the cam cover vents. I must be missing something.

[KiwiRS4T]

14 minutes ago, MrStabby said:

Yeah what's even the point of the PCV? Dont the oil drains provide a path from the crankcase to the cam covers, and there's no PCV on the cam cover vents. I must be missing something.

I think the RB25 differs from the 26 in that on the 25 the pcv does come from the cam cover.

However a properly designed catch can set up means you can do away with the pcv

[Dose Pipe Sutututu]

^ on the money...

If you're serious about track work, just delete the return pipe into the intake all in total and just run a catch can with a breather.

[JustinP]

I've got a properly baffled catch can from these guys:

http://www.saikoumichi.com/index.html

It is unused as I ended up going down a different path. PM me an offer

 

[V28VX37]

6 hours ago, JustinP said:

I've got a properly baffled catch can from these guys:

http://www.saikoumichi.com/index.html

It is unused as I ended up going down a different path. PM me an offer

Cheers mate, looks good.

I'll have a play with the one I already bought but in case that doesn't work I might be in touch

20 hours ago, KiwiRS4T said:

I think the RB25 differs from the 26 in that on the 25 the pcv does come from the cam cover.

However a properly designed catch can set up means you can do away with the pcv

19 hours ago, Dose Pipe Sutututu said:

^ on the money...

If you're serious about track work, just delete the return pipe into the intake all in total and just run a catch can with a breather.

Ok you've lost me here, I'm not sure how the PCV system works on the RB25DET Neo...?

All I was going to do is replace the rubber joiner between the LH cam cover and Scotty's intake pipe with a length of hose out to the (sealed) catch can and back, like so:

^^^ Is this a reasonable setup?

Also speaking of hose, all that SuperBarn had in 16mm was heater hose so that's what I got, anyone else running the same? I know it's not ideal for oil but still better than the kinked clear eBay hose I'm hoping.

[KiwiRS4T]

No I get my hose from a hose place - look for the places that make up hydraulic hoses (or an engineering supply store). The hose is expensive because it is heat resistant and oil resistant. I don't think heater hose will last.

http://www.enzed.com.au/Products/HoseFittingsAustralia.aspx

or http://www.pirtek.com.au/contact-us/find-your-nearest-pirtek-service-centre/

for example

Track cars may run breathers but they are illegal on the road. Besides running into the intake creates a small amount of negative pressure which helps...

[Dose Pipe Sutututu]

3 hours ago, V28VX37 said:

Ok you've lost me here, I'm not sure how the PCV system works on the RB25DET Neo...?

All I was going to do is replace the rubber joiner between the LH cam cover and Scotty's intake pipe with a length of hose out to the (sealed) catch can and back, like so:

^^^ Is this a reasonable setup?

Also speaking of hose, all that SuperBarn had in 16mm was heater hose so that's what I got, anyone else running the same? I know it's not ideal for oil but still better than the kinked clear eBay hose I'm hoping.

Just do it as per the diagram for now

In future, delete the PCV

[V28VX37]

Came up ok for a $90 setup.

Surprisingly tight to run the 5/8" hose across the engine, especially with bonnet and fan clearance.
I have no idea how people run 1 or 2 litre catch cans with a stock-ish engine bay arrangement, not much space...