DIY: Oil Catch Can Install (basic)
Thread Starter
"13B vs. Renesis" Discuss
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From: Canton, OH
I took my car in and their solution was to... void my warranty and replace all aftermarket parts back to stock to see if that fixed it.
Seriously, read through some of the experiences people have had with dealer service departments. Even if you screw something up and have to buy all new parts, its still cheaper than paying a dealer.
True story I got screwed with a 1600 bill for replacing my clutch after it burned out. My car use to be a lease car and it was never checked. I never ride it or anything then one day it just gives out and my day told them to fix it. I had to pay for it out of my pocket. I was pissed. I got on here and found all the info I need where I could have solve the problem my self. Long story short I do everything my self and it is all thanks to this community. They have the knowledge and thats what makes me glad to be an 8 owner is we are all one big rare happy family.
Hey guys.. Just thought I'd chime in..
I've been recently looking into catch cans for my other car (awd turbo DSM), and thought I'd share some info that might be applicable here.
For those that don't know, the purpose of routing line from and engine block/head (or the filler cap in the case of the RX-8) is to evacuate harmful gasses from sitting inside your engine, and contaminating your oil. If you simply just capped off the port on the oil fill tube, the gasses from the oil would eventually build up enough pressure to pop your dip stick out. Besides potentially making a bit of a mess, the gasses could also ignite. I don't know about you, but I don't like the idea of a fire under the hood of my car.
Now, there are a couple of reasons why manufacturers run a line from the block/head (or oil filler cap) into the intake:
1) The gasses are nasty, so burning them during combustion is the most ideal thing to do from an environmental standpoint.
2) The vacuum action from being tied in to the intake is the best way of evacuating these gasses in the engine.
With that said, you can certainly go ahead and place a catch can between the oil fill and a breather like what has been shown in all the previous examples. However, I would prefer to suck out as much of the gasses as possible (while trying to prevent gunk from getting into the engine). So, the way I would do it is as follows:
Oil fill -> catch can -> air compressor filter [or] carbureted fuel filter (http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053 and http://www.amazon.com/gp/product/B00...d_i=B001DRHMXW) -> lower intake maintenance ports
What happens in this setup is this: The vacuum from the lower intake maintenance ports suck the gasses from the oil fill (and therefore oil pan) which must pass through the catch can. Most of the heavy oils that were sucked out wont go past the catch can, and will accumulate on the bottom due to gravity. The little bit of oil that might get past the catch can will get separated from the gasses once they hit the filter, so only the gasses make it into the engine. There are many people out there who just use the husky filter as both catch can and separator.
note: when doing any catch can setup where part of the circuit routes to the intake, your system should NOT be employing a breather AT ALL, or else you will probably be sucking in unmetered air to the engine.
I've been recently looking into catch cans for my other car (awd turbo DSM), and thought I'd share some info that might be applicable here.
For those that don't know, the purpose of routing line from and engine block/head (or the filler cap in the case of the RX-8) is to evacuate harmful gasses from sitting inside your engine, and contaminating your oil. If you simply just capped off the port on the oil fill tube, the gasses from the oil would eventually build up enough pressure to pop your dip stick out. Besides potentially making a bit of a mess, the gasses could also ignite. I don't know about you, but I don't like the idea of a fire under the hood of my car.
Now, there are a couple of reasons why manufacturers run a line from the block/head (or oil filler cap) into the intake:
1) The gasses are nasty, so burning them during combustion is the most ideal thing to do from an environmental standpoint.
2) The vacuum action from being tied in to the intake is the best way of evacuating these gasses in the engine.
With that said, you can certainly go ahead and place a catch can between the oil fill and a breather like what has been shown in all the previous examples. However, I would prefer to suck out as much of the gasses as possible (while trying to prevent gunk from getting into the engine). So, the way I would do it is as follows:
Oil fill -> catch can -> air compressor filter [or] carbureted fuel filter (http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053 and http://www.amazon.com/gp/product/B00...d_i=B001DRHMXW) -> lower intake maintenance ports
What happens in this setup is this: The vacuum from the lower intake maintenance ports suck the gasses from the oil fill (and therefore oil pan) which must pass through the catch can. Most of the heavy oils that were sucked out wont go past the catch can, and will accumulate on the bottom due to gravity. The little bit of oil that might get past the catch can will get separated from the gasses once they hit the filter, so only the gasses make it into the engine. There are many people out there who just use the husky filter as both catch can and separator.
note: when doing any catch can setup where part of the circuit routes to the intake, your system should NOT be employing a breather AT ALL, or else you will probably be sucking in unmetered air to the engine.

We install a breather on the catch-can and simply cap the intake fitting.
Also note, the '06 models and higher already have the line routed to the lower intake manifold, so no catch can/hose re-routing is needed.
Maybe I missed something here, but I don't recall anyone suggesting a breather on the intake.
We install a breather on the catch-can and simply cap the intake fitting.
Also note, the '06 models and higher already have the line routed to the lower intake manifold, so no catch can/hose re-routing is needed.
As for those of use with '04 models (me!), I just thought it was worth while to suggest routing the hoses to the maintenance ports.
always.anthony- Only the '04 and '05 models have it routed to the intake.
A redesigned oil filler neck was introduced to run down to the maintenance ports on the intake manifold.
If you have this design, you don't need a catch-can.
A redesigned oil filler neck was introduced to run down to the maintenance ports on the intake manifold.
If you have this design, you don't need a catch-can.
Yes you do....it just moves the gunk away from the TB so you can't see it... but it's still there.
Thread Starter
"13B vs. Renesis" Discuss
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Joined: Mar 2008
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From: Canton, OH
True... You don't "need" a catch can. It won't cause the problems for you like it did for me.
However, Kane is correct also... all the oil that would go into your intake is now going into your lower intake minifold where, in theory, its burned off...
But it is best just never to re-introduce that crap into your engine.
You can run the hose from your oil filler neck to the catch can. Put a breather on the exit port of the catch if you'd like, or run it back to the maintenance port like OEM. OR, like I capped the intake port on the intake, you would need to purchase vacuum caps and cover the maintenance ports on the lower intake manifold if you went the breather route.
However, Kane is correct also... all the oil that would go into your intake is now going into your lower intake minifold where, in theory, its burned off...
But it is best just never to re-introduce that crap into your engine.
You can run the hose from your oil filler neck to the catch can. Put a breather on the exit port of the catch if you'd like, or run it back to the maintenance port like OEM. OR, like I capped the intake port on the intake, you would need to purchase vacuum caps and cover the maintenance ports on the lower intake manifold if you went the breather route.
ah ok, thank you so much!
um, there should be a little nipple thingy i can cover with a rubber cap down near the maintenance port right? (for if i want a breather)
and then if i want, i could just splice into that hose and stick my catch can in between the connections (routing back to maintenance ports)
i was going to have a catch can for a month, and if i saw nothing in it, i would just revert back.
thanks for replies guys!
um, there should be a little nipple thingy i can cover with a rubber cap down near the maintenance port right? (for if i want a breather)
and then if i want, i could just splice into that hose and stick my catch can in between the connections (routing back to maintenance ports)
i was going to have a catch can for a month, and if i saw nothing in it, i would just revert back.
thanks for replies guys!
yeah, I might flip the intake for the catch can so that the breather fits directly on the end of it... I've also got a megan can I might go with too. The ebay can came with a ton of tubing... figured I'd put it to use :p
^..............nuttin wrong with it of course, but you could always use the extra to extend the coolant bottle overflow to get it down below the power steering connectors. That's what I did.
can anyone help me? i have a question about installing, heres my thread
https://www.rx8club.com/series-i-trouble-shooting-95/catch-can-install-question-195210/
https://www.rx8club.com/series-i-trouble-shooting-95/catch-can-install-question-195210/
That may be true in some if not all cases, but we aren't talking a lot of pressure here....at least we hope not! All I did was slide the hose all the way on and use a hose clamp. The idea is still that it will flow downhill all the way out the bottom of the car. If it's able to build enough pressure to back up and come out of that joint/union, then you got serious issues and probably no coolant left at that point anyway!
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From: SF Bay Area, California
I have a question.
On the accordion hose assembly, there are actually three different nipples connected to three thoses. One of these is the one that goes from the oil filler neck to the intake. What are the two other hoses for? Are they not causing similar gunk to be blown into the intake?
I mean, we eliminate one source of gunk by installing the catch can, but may there be more that can cause similar issues?
On the accordion hose assembly, there are actually three different nipples connected to three thoses. One of these is the one that goes from the oil filler neck to the intake. What are the two other hoses for? Are they not causing similar gunk to be blown into the intake?
I mean, we eliminate one source of gunk by installing the catch can, but may there be more that can cause similar issues?
can someone enlighten me about using the 2 hoses vs. using breather and capping intake.
i have an 05 and definately want to do this but dont know if i need the breather
where would i get one too??
help is appreciated, thanks
good DIY btw
i have an 05 and definately want to do this but dont know if i need the breather
where would i get one too??help is appreciated, thanks
good DIY btw
Breather is cooler IMHO... You can get hosing, vacuum plug, and breather all from an auto parts store. Advance had everything I needed, all surprising close together.




