Dipstick popping up under boost - Finally done compression test!

[WHITCHY]

Hi guys, I've got yet another drama with the engine!
I had it on the dyno the other week, and the tuner tells me the dipstick is riding up when there is boost, its not actually spitting oil out tho.
I've done plenty of searching and found a bit of info, but nothing crystal clear to explain my symptoms.
The engine is a CA18, its running a custom oil catch can, that is connected to both cam covers, drains back to the sump, and also has a pipe running to the intake, pre turbo, which I've been informed should provide vaccum to the oil catch can to draw out crank case gases. There is no PCV valve, as its running a custom intake.
At Wakefield last Friday, the engine chewed through a bit of oil, and had the occasional smokey moment, I have pulled the intake off the turbo to check for shaft play, or oil residue, and it looks and feels fine, also pulled off the intake pipe at the throttle body to check for oil, and it was clear too.
So I am thinking this excess pressure is forcing oil out the rear seal of the turbo and straight into the exhaust?
The engine is relatively fresh, a few trips to Wakefield and general driving, so I'd say about 2000kms since it had a freshen up, block honed and new rings. So I wouldn't think it is crappy rings/bores? If I drive semi-sedately, its not smokey and doesn't drink any oil.
I'm going to try to do a compression test tomorrow to see how that looks. Then I guess a leak down test is on the list after that.
Has anyone seen anthing similar to this and fixed the issue?
Thanks in advance for any help and advice!

-Whitchy-

[oldcorollas]

The engine is a CA18, its running a custom oil catch can, that is connected to both cam covers, drains back to the sump, and also has a pipe running to the intake, pre turbo, which I've been informed should provide vaccum to the oil catch can to draw out crank case gases. There is no PCV valve, as its running a custom intake.

So I am thinking this excess pressure is forcing oil out the rear seal of the turbo and straight into the exhaust?

The engine is relatively fresh, a few trips to Wakefield and general driving, so I'd say about 2000kms since it had a freshen up, block honed and new rings. So I wouldn't think it is crappy rings/bores? If I drive semi-sedately, its not smokey and doesn't drink any oil.
I'm going to try to do a compression test tomorrow to see how that looks. Then I guess a leak down test is on the list after that.

1. pipe from cathc can to before turbo will nto provide vacuum at all. it only allows excess pressure to vent.

2. the dispstick being pushed out = excess crank case pressure.
this means you have more blowby than usual, or, your venting via the catch can is not enough.

oil on hammering sounds more like rings, esp combined with excess pressure observed.
that doesn't rule out the turbo tho

[Ben Wilson]

How much boost are you running? FWIW - Every Evo rally car I've seen has the dipstick tied down to avoid it popping out.

I agree on the leakdown test though, perhaps one of your rings hasn't seated nicely..

[TurboRA28]

Mike's EVO 4g63b engine has this problem, had to tie the dipstick down.

I did notice a bit of smoke when chasing ya at WP though.

Interesting about the vent pipe pre turbo, I thought that would be sucking somewhat?

[fixeruperer]

haha as does a 4g63 evo3 we look after.
i said its probably time to rebuild, ill give ya $5000 for it awesome lil car.

check your pcv valves and breathers.

[WHITCHY]

1. pipe from catch can to before turbo will not provide vacuum at all. it only allows excess pressure to vent.

Surely there would be some suction? Otherwise it may as well jst vent to atmo?

The turbo was fine when it went on? Awesome condition, and showed no signs of wear on previous engine?

I'm running 12psi. Would hooking up a PCV valve have any effect? Or is that only useful when the catch can / cam covers are vented to intake?

Cheers for the quick replys!

[oldcorollas]

Surely there would be some suction? Otherwise it may as well jst vent to atmo?

well.. unless you have a pressure drop across your air filter (which you don't want) then it effectively IS venting to atmosphere.....
if ya know what i mean.

ie, anything forward of turbo should be at atmospheric pressure, unless you have a restriction.

anything that vents out of it will get sucked into the turbo... but unless your air filter is restrictive, then no additional "suck" will be provided..

edit: the PCV is there to provide positive airflow through the engine, from the pipe you have to pre-turbo now, through engine, and then get sucked into the intake manifold.
it does this to remove water and fuel from crankcase as it is vapourised froom the oil. making oil last longer etc...

[fixeruperer]

yeh pcv is used between crankcase and inlet "positive crankcase ventilation" valve.
if your running a catch can and your motor is breathing well into it you shouldnt have a problem.
have you done a leak down yet.

[StuC]

check for blocked PCV valve. if its cool then suspect rings mate.

[oldcorollas]

There is no PCV valve, as its running a custom intake.

PCV is a bit of a misleading name..

since it is actually the use of vacuum that "positively" ventilates the crankcaase...

PCV is closed under throttle anyway(?), so it is a venting issue, rather than a blocked PCV issue. thoughts? (ie, PCV is a ball and spring usually, which acts as a check valve to stop positive pressure coming from manifold under boost into the crank case)

[WHITCHY]

Hmmmm, berry intelesting!

No leak down test yet, will organise one hopefully on the weekend!

So to work effectively it should really be connected to the intake post turbo, with a PCV, where it will see vaccum, and properly vent the crank case gasses?

edit: altho, at the moment, if there is excess crank case gasses, shouldn't they just force their way out through the breather on each cam cover, into the catch can, and then into the turbo intake?

[LeeRoy]

PCV is a bit of a misleading name..

since it is actually the use of vacuum that "positively" ventilates the crankcaase...

PCV is closed under throttle anyway(?), so it is a venting issue, rather than a blocked PCV issue. thoughts? (ie, PCV is a ball and spring usually, which acts as a check valve to stop positive pressure coming from manifold under boost into the crank case)

Yes but throttle shut = the most vacuum acting on the pcv, so I believe this is when it opens.

Open throttle or under boost = less vacuum so either open less or not at all.

[oldcorollas]

what Leeroy said

So to work effectively it should really be connected to the intake post turbo, with a PCV, where it will see vaccum, and properly vent the crank case gasses?

edit: altho, at the moment, if there is excess crank case gasses, shouldn't they just force their way out through the breather on each cam cover, into the catch can, and then into the turbo intake?

IF you will run a PCV to the intake, you NEED the other tube going from cam cover (to catch can) to pre turbo...

basically
when the PCV is in operation (idle, cruise etc) air will be sucked INTO the cam covers.
when on throttle, PCV shuts, and any blowby will go OUT of the cam covers..

so on throttle, PCV has no effect.

the problem is that you have enough blowby to create enough pressure, even though you have cam cover venting, to push the dipstick out.
or it is a design flaw which has something to do with the air currents in the crank case (whipped up by crank etc)

that others hav esame issue indicates your engine may not be FUBAR however, more effective venting (less restriction etc) might be something to look at after you check compression/leak down

[Cuzzo]

My old 4a started doing this, next thing i knew i had a crack piston ringland.

[The Real Roadrunner]

I had all the ventilation i could fit on my 3S (and various other high revving high boost engines) and the only thing i could do to stop the dipstick from popping out was to put a spring on it.

well maybe it didn't stop it popping out but it pulled it back in polace before i had a chance to pop the bonnet.

its a blowby thing and it doesn't matter what you do ventilation wise (unless you fit a vacuum pump) it will generally happen, i think most of the governing bodies of motorsport actually require it be held in position by something other than the o-ring.

cheers
linden