Dirty Valves from butterfly system?

[lcw1980]

Hi just wondering if this is dirty valves (crud build-up) thingy happening to all CA18det users. Anybody can shed light why this is happening and how to rectify it?

butterflies

Intake port Head

[lcw1980]

Ok I meant how to prevent this from happening again.

[bentvalves]

the corresponding valves in the head will be all mucky as well, make sure they get removed and cleaned. Do you have a head rebuild kit with new valve stem seals ?

best way to prevent it is to block the PCV valve and run both valve cover breathers to a catch tank that is vented to atmosphere.

[lcw1980]

the corresponding valves in the head will be all mucky as well, make sure they get removed and cleaned. Do you have a head rebuild kit with new valve stem seals ?

best way to prevent it is to block the PCV valve and run both valve cover breathers to a catch tank that is vented to atmosphere.

I do have a OCT thats vented to atmo on the exhaust side.

The valve stem seals are barely a year old from last years rebuild. Wheres the crud coming from and why only the butterfly ports are only affected?

TIA

[r34 gtr]

The reason those ports get so murky is because there is no fuel injector constantly cleaning them off with gasoline (which is a solvent). As there is nothing there to keep buildup from forming, it does. The *best* way to solve it would be to have the fuel injector spray evenly down both ports, but that would require a lot of work.

After taking out the whole butterfly system, the ports corresponding with those valves stay somewhat clean, but not as much so as the ones that correspond to the fuel injectors.

[bentvalves]

vent the inlet cam cover to the same catch or another catch and get a 3/4 NPT plug or whatever it is to plug the PCV port on back of plenum.

Trust me, other than doing a 4 port head, plenum, fuel rail this is your best bet.

The crud is coming from blowby gasses that are being vented through the PCV valve

[sjbsuperman1425]

i actually just experienced this whole situation, and it convinced me to take of my head, replace the head gasket, get ARP studs, and have the head cleaned...I have pics in my "unexpected find.." Thread.

thanks ks13, i'll be buying another catch can or be routing my current one to the instake side because of you. I hope you are happy ha

[bentvalves]

a picture in the ca18det FSM labels the breather pipe above oil filter housing going to the dreaded hard 90* pipe under intake manifold to the cam cover the "blowby tube" lol

Its clearly clear to me that the hard 90 is nissans jank attempt at keeping oil down in the crankcase. In any event, blowby gasses and nasty oily air still make their way into the head which is then purged via the PCV all over your hot dry a** valves (read 8 port head) A real solution to keeping oil down in the crankcase was later introduced with the breather box/stock oil catch tank on the sr20det On the topic of solutions, the 4 port head/manifold was introduced before the ca18 was put to rest.

On the topic of blocking the PCV however, just route the breathers to one larger catch and vent it to atmosphere well i.e no puny autozone filters

[bentvalves]

forgot to mention that water/meth injection would likely keep the dry valves clean. 4 nozzles tapped into the sub plenum before the butterflies that sprayed only after the butterflies opened up would cool the valves and surely clean them to some degree if not all together.

[float_6969]

You want your water/alky injection as far away from the motor, but after the intercooler, as possible. Direct port injection isn't a good idea, unless you're doing it strictly for octane purposes, and not to cool the intake charge.

Re-route/re-do the PCV system and it should eliminate that problem.

[r34 gtr]

You could just be really baller and tap the manifold for 4 more fuel injectors. That would sort it right out. Two sets of stock injectors would allow you to make really good powah.

[lcw1980]

Got little voice inside my head that tells me sumthing doesnt add up. If you look at the pictures, the port BEFORE the injectors are CLEAN as opposed to butterfly ports.

If it was the OCT system, dont you guys think that all ports BEFORE the injectors should be mucked up as well?

Modified by lcw1980 at 10:17 AM 12/11/2009
Modified by lcw1980 at 10:31 AM 12/11/2009

[bentvalves]

water injections main objective is to cool combustion chamber temperatures, It would still do its job as a directly ported injector.

LCW, not exactly understanding what your putting down.

r34, with 4 extra injectors you need an ECU capable of driving 4 extra injectors, and thats about where it turns into a pipe-dream. That would be the ultimate though 8, 370cc injectors

[bentvalves]

If it was the OCT (PCV?) system, dont you guys think that all ports BEFORE the injectors should be mucked up as well?

No because after a hard pull on rundown, when the PCV is wide open and manifold vacuum is high, the butterflies are closed (i think) and the PCV is in full effect expelling blowby gasses from the crankcase. Can you see what is taking place in this scenario?

[lcw1980]

LCW, not exactly understanding what your putting down.

Not sure how to say this any better, hmm what i meant is that why the whole pipeline BEFORE coming to the port with injectors are relatively cleaner than the ports with butterfly flaps?

If muck is due to the blowby gas, why the area BEFORE the injectors is clean since the blowby-by gas is sucked down into ALL 4 ports?

[bentvalves]

oh ok i see what your saying.

maybe reversion of the fuel mist to some degree? Who knows the dynamics of what goes on inside that manifold when those butterfiles are fluttering about.

for the longest time I hated the idea of not running the PCV valve. It is what is is though, and for what it is, capping the PCV is the best option imo. Even then, the dry valves will still get dirty because of oil mist in the intake tract which is inherent with turbo cars, but the PCV is the real killer in terms of muckage.

[r34 gtr]

Greg, my ECU will run as many injectors as I want it to. Ha!

[bentvalves]

Plumb injectors everywhere then, 8 wont cut it at this point. Do 8 in the fuel rail, 2 before the throttle body, 2 on the back of the intake plenum, one pre turbo, 5 in the intercooler, and 1 in the downpipe about 18 inches behind turbo. Use various different types/brands/impedance of injectors to make it more fun and...run lots of boost.

[r34 gtr]

I like the way you think. The one in the down pipe is key.

[float_6969]

LMAO. I'd pay money to see the one in the down pipe.

[D_Stirls]

Valve stem seals are probably having a hard time on the runners that have the butterflies. When the butterflies are closed there would be a huge vacuum built up behind them as (obviously) the intake valves still open and try to draw in the intake charge. With the huge amount of vacuum there would be a fair bit of pull on the valve stem seals and they probably pass a bit of oil/


Modified by D_Stirls at 3:57 AM 12/18/2009

[Valvebounce]

Thats sounds plausible.

I wont be getting any problems with the other valve getting scoaty.

scored this for a great price.

[bentvalves]

now on rundown after a good hard pull, are the butterfiles open or closed when manifold vacuum is at its highest?

good point d-stirls - about the strong vac behind the buttefly, never took that into consideration

[lcw1980]

So the oil is probably forcibly pulled from the valve stem seal when butterflies are closed?

On another sidenote, does sr20det without any of this butterfly system gives better torque down low comparitively to the ca18?

[bentvalves]

next time I pull my intake manifold off the head I will see how things are coming along with the PCV valve plugged. If the valves behind the butterflies are still mucked up, it will be safe to say that the oil is being pulled from the valve stem seal as d-stirls has suggested.

if this does happen to be the case, I think I will drill a few small holes in each butterfly to alleviate the vacuum that is created behind it.

[Danski]

next time I pull my intake manifold off the head I will see how things are coming along with the PCV valve plugged. If the valves behind the butterflies are still mucked up, it will be safe to say that the oil is being pulled from the valve stem seal as d-stirls has suggested.

if this does happen to be the case, I think I will drill a few small holes in each butterfly to alleviate the vacuum that is created behind it.

I've had my butterfly's and runner removed and the same thing still happened. My guess would be that the entire intake manifold acts the same way and the effect happens on both sides however only one side has the fuel necessary to stop the build up. It was rather bad on mine, crust built up on the guides and everything. Also my breathers are plumbed to a catch can that vents to air so it's not that.

[lcw1980]

I've had my butterfly's and runner removed and the same thing still happened. My guess would be that the entire intake manifold acts the same way and the effect happens on both sides however only one side has the fuel necessary to stop the build up. It was rather bad on mine, crust built up on the guides and everything. Also my breathers are plumbed to a catch can that vents to air so it's not that.

that sucks, which means butterflies or not, the crud will still build up . In other words, nissan screwed up with the CA design? All hope is lost?

[Danski]

Well if crud on the valves really bugs you that much then yes, unless you do something drastic there doesn't seem to be an easy solution to fix it. However don't let my advice stop you from trying as you may think of something.

[sjbsuperman1425]

well here is what i am going to be doing for the intake side of the PCV system.

zerothread/186408

basically a catch can, something that i can actually SEE collect the oil. I dont know how good/if it will work, but I couldn't go wrong for $20. My intake manifold and head were pretty nasty, as i said before, and I did burn a bit of oil. Hopefully this will make things better.

[bentvalves]

when you removed the butterflies in the sub plenum danski, did you rebuild the head at the same time to get all the inlet valves spotless? I wouldnt say all hope is lost lcw as the 8 port jap heads can sure still get the job done, 4 dirty inlet valves or not