[s-cars] LONG: failed head gasket causing excessive oil blowby?

[Ray Tomlinson]

Patient:  95.5 S6, 149k miles.  RS2, Garrett hybrid.

With only small K&N crankcase breather (direct vent to atmosphere) installed
and daily driving, no measurable crankcase blowby.  At the track, however, I
would "preserve" the EM with a nice misting of Mobil 1 (here, here, Brian
and Trevor . . .).

About 2 weeks ago, I install a GReddy catch can (15mm) with sight glass.
Normal driving with bursts of heavy boost, no track time, absolutely NO oil
registering in the sight glass (tube, actually).  Even with GReddy catch
can, still venting to atmosphere.

First day at track (yesterday), I am running the car hard.  Real hard.
Catch can registers about 75% in one session (about 1/2 quart), with another
1/2 quart blowing all over the damn engine bay out of my trusty breather.
Check dipstick - 1 quart low.  I have never noticed this quantity of blowby.
To further compound the situation, I notice that the damn nipple on the
radiator expansion tank decided to give up the ghost, but a ziptie and
racer's tape will fix anything.  (okay, the racer's tape was simply for
effect).

I empty the catch can and replace the expansion tank.  Head back out on the
track.  Climbing up the hill out of Turn 3 at NHIS, I look behind me to see
thickest white smoke known to man, filling the entire turn.  Sure, I was
working the tires, but this seemed ridiculous.  Crowd cheers.  A quick
glance at the gauges shows normal water temps and moderate oil temps, but no
coolant smell.  After the crest of the hill, no more smoke.  Good throttle,
boost and brakes.  Pull into the hot pit, (worthless) coolant light is
blinking at me.  Pull into the paddock, coolant tank about 1/2 full,
bubbling, below min, but visible in tank.  At no time did the car overheat,
and both electric and viscous fans operational.  Car has lumpy idle, and
obvious lifter chatter.

Catch can AGAIN has about 1/2 qt. of oil in it.  Dipstick reads about 1
quart low.  I'm beginning to think that my PCV valve is stuck, or something
is causing excess crankcase pressure.  Car was running like a champ, so no
reason to believe low compression in one or more cylinders.

Quick shout to NEA, and a new expansion tank is on the way, along with some
more coolant, thinking that "if I have it, I won't need it."  Wrong.  After
the car is cool, I replace the expansion tank and drain the catch can.
Start car - lumpy idle, LOTS of white smoke.  Blip throttle - still white.
Coolant level doesn't drop, temps come up to normal, smoke disappears.  Shut
car off, cool down for 2 hours.  At end of day, start car.  Lumpy idle, lots
of white smoke.  Exhaust doesn't smell rich with coolant.  I begin to think
fouled plug, faulty injector or failing coil/POS.  After car is warm, smoke
disappears and idle smooths out somewhat (7A exhaust cam is a little lumpy
with the big turbo).  Decide that test drive is in order.  Shut car off for
a few minutes while I clean up my mess.  Car starts hard (barely), lumpy
idle, and lots of white smoke.  Idle for 20 minutes or so, drive around
paddock, no coolant loss or usage, but I did not get into the boost.  Smoke
disappears, idle smooths out.  Everyone agrees that I am simply paranoid.
Maybe they were right?  WRONG.

Leave track for drive home.  Despite lumpy idle, car pulls just as strong as
always and holds boost.  Turbo sounds fine.  Under heavy boost on the road,
I see the same rich puff of smoke that I have always seen with this turbo
and Uncle Bob's RS2 software.  NO oil blowby registering in the catch can,
but I only got into the boost twice, and for brief spurts only.

Trip back from NHIS to Boston takes about 1 hour 15 minutes while observing
MOST traffic laws.  After 3o minutes, coolant light comes on.  Reservoir is
again at 50%, just enough to trigger the switch.  I grab a burger and allow
car to cool for 2 minutes.  I top off the coolant, fire it up.  Lumpy idle
and misfire immediately returns on startup, plenty of white smoke.  After
warm, misfire, lumpy idle and white smoke disappear.

NO, I have not YET performed a leakdown or compression test.  Car pulls like
hell.  NO, I have not YET pulled the plugs.
YES, it drinks coolant (1/2 gallon in 1 hour).  And YES, I can now smell
coolant in the exhaust.  NO, I am not seeing any coolant foaming on the
dipstick.

I'm thinking that a blown head gasket is causing coolant to fill one or more
cylinders, causing the lumpy idle.  Assuming that the head is still fine,
any reason to believe that a blown headgasket is causing excessive crankcase
pressure sufficient to push 1 quart of oil out of the head in 30 minutes of
track time, or is it possible that my PCV is stuck or otherwise faulty???
(Yes, I will check the valve's operation when I have the head off the car).

Aside from tearing down the motor, am I missing anything obvious?  Tomorrow
is a new day (for some people, that is).

TIA,

Ray Tomlinson
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