Crumpets
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Post by Crumpets on Jun 10, 2021 13:04:50 GMT
Good afternoon to you all, I'm hoping that someone could possibly nudge me in the correct direction in fixing my misjudgement when it comes to my PCV setup. After turboing (and also fitting the catchcan) - I've noticed that the catch can is filling up after about 60 miles, and leaks from the breather after about 30/40 miles. I'm pretty sure it's because i've hooked it up incorrectly, but i'm hoping someone can show me the error of my ways. I've tried to detail how its set up as detailed as i can in the below photos:   ![]() Your thoughts / telling me i'm an idiot are welcomed haha  |
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Post by atlex on Jun 10, 2021 15:11:29 GMT
So... I'll get stuck in with my thoughts.
Your setup:
It's clearly VTA via catch tank - you're not putting the fumes back into the inlet manifold..
That PCV valve, unless drilled out, is just blocking flow so you're only filling the catch can up via the rear 'no valve' direction (which would be fine) but that pipe should probably be the 'air source' for cross flow through the head in a NON-VTA setup.
Check: the two pipes and see which of them is the greasiest ?
So with that assumption ..
Given the path via the PCV valve is blocked, it's also the best 'exit' for avoiding massive amounts of oil because it is angled up, the oil would have to fight gravity to go up.
Fix ideas given the above:
1) Take out the PCV (it's just a blocker on a VTA setup) and put in an unrestricted plumbing fitting like brass or metal and...
2) Cap or put a filter (again, angled up so oil can't easily find its way out) on the 'back' breather tube.
If neither of these things work I'd also take the cover off and check the baffling. YOU REALLY WANT BAFFLING. - without it, the oil finds its way out the head just way too easily.
You're already running a modified cam cover, maybe someone took the baffling out ?
3) Consider a draft tube to keep flow through the head - so that you have flow when the car is moving - you want most flow out the 'where the PCV would be' breather hole because it has the up-angle and hopefully, baffling.
Other considerations:
Check how much blowby you have. To do this cap all but one of the breathers, or all the breathers and check on the oil filler cap. You could have 'too much' and this could be helping to force the oil out. This combined/with messed up baffling or having most of the breather fumes go out the worst of the two breather holes.. might explain it.
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Crumpets
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Post by Crumpets on Jun 10, 2021 16:53:37 GMT
Hey atlex Thank you so much for your detailed response. To clear up some things: That PCV valve, unless drilled out Nope, its not drilled out; although I need to check to see if it is actually working as intended. Check: the two pipes and see which of them is the greasiest? I will check and report back this weekend. You're already running a modified cam cover, maybe someone took the baffling out ? It has baffling compartments: Prior to paint I had the rocker cover media blasted & once done I removed the covers and cleaned them all out. They're empty, but there. See photo below taken from the web, albeit mine are empty.  Perhaps this online guide from the 323 would help? Would this be a wise move to pack the breathers to try and mitigate oil being pulled through the PCV system as per the above photo? I'll also check the blowby on the weekend, although i must admit I do not know how much too much would be? What should i expect to see from a healthy engine? (My engine has 65,000 KM's on it so fairly low mileage) Do you think that changing the setup to remove the VTA would be beneficial? I'm not exactly sure how i would achieve this- perhaps by changing the VTA filter for a line into the intake mani? I would also put the PCV valve in this line and put a standard barb where the PCV currently is. Your thoughts? Thanks Crumpets |
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Post by atlex on Jun 10, 2021 20:53:21 GMT
What I'd do ? Staying VTA I'd... probably want to do the road draft thing if this was mine :-)
Don't bother adding things to the baffles they should work as designed if you keep the flow out of the correct one where the PCV valve would go.
I'd put a filter on the breather opening at the back of your engine.
Drill out the PCV or replace it with a barbed hose joiner (I recommend keeping it intact in case you want to reuse it..)
Run a hose from the drilled PCV / barbed connector to the catch tank.
Blank off where the current filter is on the catch or use that as the outlet for the road draft tube... make sure there's only one inlet and outlet for the catch.
Where the other hose was that would have gone to the back of the engine I'd run that hose down into the air stream under the car for the free air flow.
The flow would be like this when the car was moving through the air ...
air filter at back of the head => the cams + breather fumes enter the mix => baffled section => up through the barbed fitting/drilled pcv => the catch tank => the road draft tube down at near the front arms (and our beloved environment)
When the car wasn't moving you'll see some fumes coming out the air filter at the back of the engine but not too much.
Alternatively I'd go back to putting this fumes into the intake of the motor once they'd gone through the catch. Keep the PCV where it is and intact, instead of a road draft tube put the hose out the catch tank to the intake manifold. You could even use the brake booster T-off. Just fit a T-fitting there.
Maybe that intake mani you have has another fitting already usable.
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Post by dadbif on Jun 10, 2021 21:24:16 GMT
Shouldn’t there be cover plates over the baffle areas under the cam cover?
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Crumpets
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Post by Crumpets on Jun 11, 2021 5:48:43 GMT
Thanks again atlex I'll give that a go this weekend and report back. Shouldn’t there be cover plates over the baffle areas under the cam cover? Yes, there are. Photo was for illustration: the baffles are covered by plates that are also silicone sealed in place  |
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Post by atlex on Jun 14, 2021 8:32:30 GMT
How'd you get on ?
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Post by howardb66 on Jun 14, 2021 13:55:56 GMT
Just out of interest, should there be breathers on both sides of the cam cover?
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Post by Zed. on Jun 14, 2021 17:06:21 GMT
Just out of interest, should there be breathers on both sides of the cam cover? not nessessairily, mazda used 2 with one having a pcv fitted & the other to allow re-breathing / recirculation of combustion 'blow-by' when the vacuum pcv system is not operating. a single camcover / cylinderhead 'breather' can be used (even better to have a crankcase breather but that's a bit of work on a 1.8 engine) Rich. |
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Post by atlex on Jun 14, 2021 19:32:51 GMT
They're both standard cam covers for the B series engines.. the one in question here is just not being used as it was intended (with a regular PCV system leading to the intake manifold).
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Crumpets
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Posts: 227
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Post by Crumpets on Jun 16, 2021 20:48:45 GMT
Good and bad; The oily line was the one on the back without the PCV. I drained the catch can and replaced PCV with a barb. It's still filling up; just not as fast. I think started to show 3/4 full (showing oil on the glass) after 150ish miles? I have checked blow-by, and it is no different to how it was when N/A. Not very much at all actually; this may however change when at high RPM or in boost? After speaking to a local-ish MX5 guru for a 3rd or 4th opinion; he has recommended ditching the catch can and just venting the rearmost port to atmosphere and blocking the front one up? - Thoughts? I'm starting to think that maybe the rocker cover may be the issue? It has been modified to fit this particular application; what if the PCV / breathers have been done wrong? I can't see how two VTA breathers via a catch can should fill up so fast? I might even run the OE cam cover for a week or so and see if the situation improves to try and mitigate the catch can being the problem? Either way, I've put the car away for the week and will likely come back to it when I have more motivation for problem-solving  Crumpets |
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Post by Zed. on Jun 16, 2021 21:10:43 GMT
you have a Mazda 323 (fwd) camcover, how are they plumbed from the factory? (turbo & na might be different covers & different plumbing  ) mighty5s.com/post/47159/threadRich. |
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Post by atlex on Jun 16, 2021 21:58:25 GMT
Good and bad; The oily line was the one on the back without the PCV. I drained the catch can and replaced PCV with a barb. It's still filling up; just not as fast. I think started to show 3/4 full (showing oil on the glass) after 150ish miles? I have checked blow-by, and it is no different to how it was when N/A. Not very much at all actually; this may however change when at high RPM or in boost? After speaking to a local-ish MX5 guru for a 3rd or 4th opinion; he has recommended ditching the catch can and just venting the rearmost port to atmosphere and blocking the front one up? - Thoughts? I'm starting to think that maybe the rocker cover may be the issue? It has been modified to fit this particular application; what if the PCV / breathers have been done wrong? I can't see how two VTA breathers via a catch can should fill up so fast? I might even run the OE cam cover for a week or so and see if the situation improves to try and mitigate the catch can being the problem? Either way, I've put the car away for the week and will likely come back to it when I have more motivation for problem-solving Crumpets so all the oil getting to the catch can was through that rear port. you've now split the flow by replacing the PCV with a barb... and now half that flow is taking the path via where the PCV was, is a harder journey for the oil to take. the fact that the oil was previously ONLY going via the rear port means that that port has the worst baffling and a path of no resistance for the oil to escape. you want to stop flow out that rear oily one, it should be no flow or mostly flow in the opposite direction.. (hence the small filter + draft tube idea I ventured earlier) simple fix now is : block the rear port and only use the side port where the PCV was (and now the barb is). it's higher and the baffling is superior. ditching the catch can won't solve the problem unless you stop flow out the back port. You'll still be dumping loads of oil out it - the catch can is just letting you measure how much. for comparisons sakes.. on my ITB car I run VTA with a draft tube on the other port of the (two port) can. There's a filter on the other "non-PCV" port on the cam cover to allow cross flow, but I can replace it with a blanking cap for MOT time since they hate seeing breather filters. My catch can never fills up because the oil never manages to get up through the baffles to the barb and breather line in any measurable quantity. It's angled up so any that does I suspect just flows back down into the baffle area !! |
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Post by dadbif on Jun 17, 2021 7:15:23 GMT
I realise catch cans are required for the track, for obvious reasons, but why have they become an aftermarket “fashion accessory”?
I cannot think of any manufacturers who fit such complications, older vehicles used to have gauze traps etc that then drained back into the rocker cover. Simple but effective.
I have no such contrivances in my car, do not suffer oil leaks, and my small breather filter on the exhaust side remains dry.
Excessive oil misting would indicate to me that you are suffering from piston blow by…. or have induced, by modification, a pressure imbalance in your engine.
But I’m old and like to keep things simple, what had Mazda done that was so wrong with their exhaust gas recirculating system?
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Post by Zed. on Jun 17, 2021 8:06:10 GMT
I realise catch cans are required for the track, for obvious reasons, but why have they become an aftermarket “fashion accessory”? Because scene-points?  why follow the herd when you can add individuality? sorry, I'm being sarcastic Rich. |
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le sigh