Breather set up

J

jambo_gtir

Member
Right guys, I have spent ages searching the internet and forums about this and still not sure what to do.....

The problem I have is my engine is using oil and blue smokes a tad after over-run down a long hill (then re-applying throttle) and also when I come on full boost it smokes initially then stops.


The engine build is less than a year old with about 5000km on it. I have done a compression test and leak down test and both are good. I have also recently replaced the valve stem oil seals with some supertech ones. Also, I bought a brand new turbo off Bobby a few months ago. It still burns oil......


I think i know what the problem is: the new bigger turbo (3071r) meant that I had to change the oil return to the block. I spent weeks buying different bits of samco hoses and 90 bends etc to try and get the oil return to travel down to block. Due to the position of turbo and adaptor in the block its is so hard to get a decent oil return. I know that this is simply gravity fed so needs to run 'downhill'. Anyway, I finally have an oil return that is almost downhill when the car is level....


The next issue is my breather system which i suspected was crap and hence pressurising my crank case (addidng to the oil drain problem). So i took standard system out and put my own in. The engine does seem to run better now and I think the oil problem has improved but it is still smoking on initial boost and burning oil.
Just to mention I am running quite big ring gaps so i suspect have more blow by than standard.


Basically.... i know most people run the breather to atmosphere but I am thinking about running mine through my catch can first and then back into turbo intake (as Nissan does). I think this would 'suck' gasses out causing more of a vacuume in crank case and impoving my oil drain from turbo (and hence stop the oil leaking from turbo seals). The trouble is on most forums people say there is no vaccume in the turbo intake pipe? how is that possible when the turbo is is sucking in air hard??
Is it really that bad to run it back through turbo like Nissan does? most people argue Nissan only do it for emissions but i think it's more than that....it must suck the crank case gasses out to create a vacuume and promote ring seal surley?


Sorry for long post, this is just the final thing wrong with my Pulsar now and I really want to sort it out before I end up driving the thing off a cliff!!
 
PobodY

PobodY

Moderators
Staff member
I'm no expert, but it seems to me that drawing a small amount of oil vapor through the turbo can't be that bad for it. - I'm not suggesting that droplets hitting a blade spinning at high speed doesn't have the potential to do damage; I'm just saying that if there's a small amount of oil in the vapor I think that would lubricate everything from the other side.
That's why I've kept the standard separator (although most everything else is also standard, so that's not a hard decision).

There may be some related issues like the intercooler collecting oil, but if there's that much going in you've got bigger problems.

I think the original Nissan design was like this: the PCV opens and sucks the crank case emissions into the inlet manifold to be burnt-off; the other end (attached to the inlet) lets "fresh" air into the crank to replace anything that has been sucked-out...when there's no vacuum on the PCV the crankcase is free to vent into the inlet pipework. - So you're right in thinking that the original design is to use vacuum to scavenge the crankcase. There's probably a semantic point in that there may not be vacuum before the turbo, but you will still get a venturi effect from the air rushing past the port which will draw on it

I guess the advantage of a catch can that vents to the atmosphere is that (a) you can see how much oil it has collected, and decide whether that's a problem or not (b) it doesn't let everything get a light oil film on it, thereby keeping things clean(er).

I think the best solution I've seen in the Forge oil/mist separator which simply replaced the factory black box and (probably) does a better job of sending oil back to the sump and vapor to the inlet (to go through the turbo and be burnt).
 
P

pulsarboby

Guest
have you got an oil restrictor fitted in oilfeed to turbo?
is the pipe back to crankcase return kinked in anyway? if so this can be a huge problem as pressure can build inside turbo and blow seals etc
does the smoke get better after engine is hot or is it the same hot and cold?

with regard to breather setup
use the pcv valve back to inlet plenum, if you blank it youll just create excess crankcase pressure as its hard for pressure to escape from just one point of rockercover

the other end should ideally be run with some form of catchcan which utilises the induction pipe to actually draw the gases from the crankcase when coming on boost (basically the same as nissan originally designed) so ideally you need a 3 point catchcan with one side going to rockercover, another outlet going to induction pipe and a third outlet going back to crankcase, the oil build up can be monitored and drained as necessary that way



yes martyn the turbo was brand new and unfitted
 
J

jambo_gtir

Member
Cheers for responses guys.

Bob: No I haven't fit a restrictor I thought it came with one internally? My drain pipe isn't kinked either as used pre-bent tubes and spent ages making up a decent pipe that would do the job.

Markturbo: Yes mate I have taken that out. My setup at the moment is the PCV valve blocked up. A new pipe from crank case to new catch can, then a new pipe from the right of rocker cover to new catch can, then the catch can venting to atmosphere. The hole on the intake pipe i have blocked up obviously.

I'm worried I have weakend the new turbo now which isnt good.... It seems ok when its cold but gets more apparent when hot. I can fill my oil to max level, then after a week its down to min.....that's quite a lot of oil going somewhere and it isn't on the floor :(
 
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P

pulsarboby

Guest
some came with inbuilt restrictors and some didnt and are in the lines tbh im not sure on whether thats built in or not.

check for any play on induction side of tubby if its now damaged the seal or bearing then there will be excess play in it, especially as your using that much oil (thats a hell of a lot)
i know you had the same prob before the turbo so its most unlikely to have the old one and the new one doing the same thing which would make me think its an engine related problem you have or problem with breather system not breathing correctly
 
red reading

red reading

Active Member
You have forged pistons and big ring gaps, unless the engine is pushed hard constantly on the track it will use oil, all ball bearing turbos supplied in the uk now have the oil restrictors fitted, your car is burning oil because you built a loose engine and under vacuem on over run it is pulling oil past the piston rings then when you use the throttle it is burning it off it is advisable to fit a inline filter to the turbo though. And put that black pipe back in place or you will chuck oil out of the crankcase, the breather system on our cars is fine even with big bore stroked engines nme actually block the crankcase breather and just use the rocker cover ones. And there should be no vacuum in the pre turbo inlet pipe other wise you are massively restricting your car the breather to the inlet is just to burn off gases in the crankcase not create a vacuum in the crankcase.
 
M

MarkTurbo

Well-Known Member
red reading said:
And put that black pipe back in place or you will chuck oil out of the crankcase, the breather system on our cars is fine even with big bore stroked engines nme actually block the crankcase breather and just use the rocker cover ones
Click to expand...
As I found out the hard way :oops:

Jambo, there is a small restrictor in it and without it fitted like Danny said you'll just keep chucking oil up into the breather system/catchtank.
 
J

jambo_gtir

Member
Thanks for the help guys, I have just been out and put the breathers back as normal. The only difference now is I have larger pipes and a catch tank between rh rocker breather and turbo intake pipe.
Is there nothing I can do about the loose engine then? I am running 24 thou gaps on top ring and this was spot on across the whole bore, so indicating a good rebore I assume.
I have filled oil to max so ill see how much oil I consume between now and next weekend!
 
J

jambo_gtir

Member
Well I can see it in wing mirror mate when I'm on a well lit road. I'll have another go tomoz and get my mate to follow me and film it.
Thanks again for the help everyone, much appreciated.
 
S

Sven777

New Member
If its that bad that you can see it in streetlights: just after driving (warm engine): let it idle for like 2min and take the oil filler cap off with the engine running. If pushes out smoke or sputters oil your engine is to shit.

By the way; if you want to truly upgrade the standard oil seperator system whilst keeping the stock setup: Saikou Michi Co. Design
 
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