HELP CA18DET breather and catch can problem HELP

[troopiec]

Hi guys, My name is Colijn, i have joined and introduced myself before a couple years back but cant remember my details to reuse that account so had to make a new one, anyways heres a brief spec of my car:

I live in South Africa and im driving a euro spec 1991 200sx RS13 with a ca18det. Mods are as follows:

- 76mm straight through exhaust
- walbro 255lph fuel pump
- garrett s14 t28 turbo at 1bar boost
- custom topmount manifold i built myself
- 38mm external wastegate
- turbonoz stage 2 eeprom chip
- front mount intercooler with 50mm hot side boost pipe and 63mm cold side boost pipe
- hks replica ssqv dumpvalve
- AAC and idle valves removed and blanked off
- motor internals stock standard never opened motor up in 6 years since ive had it

Last dyno was 169kw and 303nm at the rear wheels



Anyways heres the story. Ive been running my setup above reliably for about 2 years and my breathers were always left open and PCV valve blanked off as i didnt want dirty oily vapours in my clean boost pipes and intake etc. The car drove perfect without any issues this way however when i used to drive the car very hard redline or spinning etc the exhaust breather would spit oil onto exhaust manifold and smoke and i constantly had crankcase fumes smelling in the passenger compartment so i decided to fix it properly, so i did my research and read on all the appropriate forums on correct catch can setups and did comparisons etc. I am a qualified mechanic and im well aware of how the PCV system is supposed to work so i installed things as per factory except with the addition of a catch tank to try reduce oil getting into turbo intake and boost pipes etc. However after the full install i came into the problem where my dipstick was blowing out and oil was spraying out, and i have never had the dipstick pop out ever before the catch can install. Oil level correct aswell. I will post pics of the setup now and how the breather system was effected in each example:

Original Setup derived from factory design with catch tank added, so PCV valve will scavenge crankcase pressure on idle and cruising and then on boost the pcv would close and turbo would scavenge crankcase through catch tank and not suck as much oil:





this was done with catch tank unbaffled but fully sealed, test drove it down the highway and gave it 7000rpm boost a few times, pull off to check and i find dipstick popped up and sprayed oil on manifold, catch tank had about 50ml oil in it and turbo did suck a bit up but not much. So since i took the PCV valve out like 3 years ago before this i figured ok the pcv probably just leaked boost into crankcase and popped dipstick. So i blanked off PCV valve again and T'd the breathers together, heres Setup 2:

Setup 2 with PCV blanked off again and breathers pieced together and turbo alone scavenging:







Test Drove car again down the highway as before 7000rpm a few times, pulled off, again same story dipstick popped out and oil sprayed, this just doesnt make sense to me, yes im well aware that my rings etc may be worn and i have excessive blow by, but the car pulls like a train and it never used to pop dipstick when the breathers were open, and besides even with very bad blowby the vacuum from the turbo should be sucking up all the pressure even if my rings were completely stuffed. So i tried one more thing to make sure its just the catch can setup, so heres setup 3:

Setup 3 with breathers T'd onto catch can and catch can simply venting to atmosphere, no vacuum on catch can and turbo inlet pipe piece blanked off







Test drove vehicle like this again down highway nice and hard on a warm day, 7000rpm a few times, pulled off and checked engine bay, dip stick still seated nicely and no oil spraying anywhere, catch can had about 120ml oil in it now but thats including the previous 50- 60ml that was aquired during previous test runs.

So my question is what am i doing wrong, what can i do to improve my situation without a rebuild? the motor is pulling strong and not smoking, im not going to overhaul it for a small breather issue, noted also theres no sludge in motor i do an oil service every now and then as little as 3000km intervals, motor is gold inside.

Or must i just live with a vented catch tank and have to smell the fumes.

Any input would be great, sorry for the long post!

[ANDY black s13]

What have you done to the engine block breather pipe that runs under the inlet runners and up to the inlet cam cam cover ?
(and the 90 degree exit union fitted in the block) , I read it twice and couldn't see it mentioned ,
the metal pipe can block at the crimped or dented bend area, and the exit tube can fill up with engine crud
if he can't vent properly dipstick/dipstick tube is next exit path
mine used to do the same,clearing the 90 degree bend and running a fat pipe from it to catch can helped on mine,stopped it blowing out the Dipstick
need inlet plenum out the way to get to it,and to check for crud/clean the 90 degree union properly
my engine was very tired and breathing heavy/fumes from breathers etc,bit down on compression but still pulled hard,ran sweet and idled nicely
just had an appetite for engine oil and needed catch tank draining often, did 30k miles till the big ends cried enough
not saying that's what is up with yours,but could be if not looked at and cleaned in the past

that's a very nice and clean build btw

[Jonny Wilkinson]

I'd agree with Andy. Most likely problem is a blocked crankcase to head breather pipe. If you have blowby due to worn rings and the poorly-designed crankcase to head breather is blocked, the dipstick will pop.

The oil emulsion that ends up sitting in that pipe carbonises when it gets hot and causes a build up of coke inside the pipe. It's hard to get at too Pretty sure you need to take the plenum off to get to it.

[troopiec]

Hi Andy and Jonny thanks for the advice and the compliment, that pipe could possibly be blocked, when I had intake off to polish it about 3 years ago I checked the pipe and it was clear but alot has been done since then, this weekend il try have a look at that breather pipe. But also remember I said dipstick doesn't lift if the intake tappet cover breather and exhaust tappet cover breather is left open to vent to atmosphere, does that still indicate that hose could be blocked even though I can feel clear breathing from both open tappet cover breathers? I was under the impression that the crankcase vent on the intake side is from that pipe in the block to intake tappet cover to allow it to breath out the fitting on tappet cover to pcv? Or is there additional breathers through head on intake side that I'm feeling coming out of the intake tappet cover breather?

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[Jonny Wilkinson]

I'll have a look at your pictures tonight. I can't see them at work.

I did do quite an indepth post about how the pipework is set up and works a couple of years ago but don't have time to search for it now.

[troopiec]

Hi Jonny I would appreciate it if you could find some time to dig up your old writeup i'd love to read it then

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