<VV> Total Seal rings and turbo oil smoke

Sun Jun 24 14:18:44 EDT 2012

I understand your points and suggestions.

Regarding the "normal" oil consumption, the ~800 miles per quart was there
when I bought the car (the first owner put 27k miles in 15 months --
probably pretty hard miles), then again after the engine was rebuilt at
~60k miles with new GM cylinder assemblies (they used to sell complete
cylinders, pistons & ring packages), and finally again after the
restoration at ~120k miles when the cylinders were bored and I used the
Total Seal rings.  Oil consumption over 40 years, ~90k miles and three
different sets of rings has been pretty constant at 800 miles/quart.  I
can't believe all three sets of rings (factory original, GM new cylinder
kits and the latest rebuild with T.S. rings) have never seated properly.
I'm pretty confident that the oil consumption was due to minor seepage from
the carbon seal and/or the turbine side ring.  I have no idea what Chevy
thought was "normal" oil consumption, but I'd bet they would have
considered 800 miles/quart to be acceptable.  Keep in mind that the oil
seals on the TRW turbos was pretty primitive by modern standards.  I'm sure
there was a considerable range of how well they sealed.  I just got one
that's on the leaky side.

The new symptom is clouds of smoke at hot idle; not consistently, but
frequently enough and dense enough to be at least annoying.

I just ran a compression test and it came out great.  First stroke was over
120 psi, three revs brought each of the cylinders to between 140 and 150
psi.  So at least there's good compression.  While I was fooling with the
engine, I replaced spark plugs (using a set of AC44FFs, had been using
Bosch W8ACs), rotor and cap.  I checked timing and found one anomaly -- the
Dale "advance/retard" unit had failed; the diaphragm had ruptured so it was
proving neither advance nor retard and in fact producing a significant
vacuum leak.  I replaced it with a new spare pressure retard-only unit.

I reset the timing to factory spec and upped the idle a bit to ~950 rpm
(factory setting is 850 for a turbo).  I haven't taken it out and given it
a thorough highway heating, but at normal idle operating temperatures,
there's no significant oil smoke unless goose the throttle.  Then there's a
small puff of oil smoke as it clears it's throat.

The PCV system is clean and clear, but thanks for the suggestion.  And the
oil drain line is clear as well.  (Anything that restricts the oil drain
from the turbo would certainly lead to massive oil smoke!)

I'm beginning to think that it may be that I had the idle speed low enough
that the turbo wasn't spinning at all at idle.  (Does anyone know if the
turbo spins at normal idle?)  In that case, oil could pool behind the
carbon seal (no spinning to sling the oil off the shaft) and the high
vacuum could draw some past the seal.  At a higher idle, there may be
enough exhaust flow to keep the turbine moving and thus sling oil away from
the seal.  It's a hypothesis anyway, but other than trying various idle
speeds and seeing what happens, I can't think of a way to prove it.

At this point, I'm likely to "just live with it" until it becomes so
constant that it really needs to be fixed.

Aren't Corvairs fun?

Jim Simpson
Group Corvair

On Sun, Jun 24, 2012 at 12:32 PM, shortle <shortle556 at earthlink.net> wrote:

> Not knowing much about turbocharged Corvairs I should remain quiet. But
> how about the PCV system. I am sure the chrome nipple and the vent pipe and
> the chrome tube going to the air cleaner housing all needs to be very
> clear. And of course the turbo oil drain pipe needs to be very clean and
> open as well. IMHO these are worth checking.
> Timothy Shortle in Durango Colorado 81301
> I have enough trouble with naturally aspirated Corvairs (mostly valve
> seats)
>
>
> -----Original Message-----
> >From: Mark Durham <62vair at gmail.com>
> >Sent: Jun 24, 2012 10:13 AM
> >To: Jim Simpson <simpsonj at verizon.net>, Virtual Vairs <
> virtualvairs at corvair.org>
> >Subject: Re: <VV> Total Seal rings and turbo oil smoke
> >
> >Jim, the dynamics of using a quart every 800 points to the fact that
> >the Moly rings never seated properly And you have always used more oil
> >than you should. You say they honed the cylinders extra for the Moly
> >rings, probably due to the fact that Moly works better with a different
> >cross hatch pattern, finer, I think, and if that is the case there are
> >two things that could be a potential problem, the hone job was botched
> >which ate up your rings, and honing took the barrel diameter to the
> >outside of the limits which lowers tension on the barrel walls.
> >
> >Also a potential problem is the .040 barrels, that could have warped
> >over time due to the extra turbo heat. If a top overhaul is not in you
> >near future, go buy some 20/50 oil and put in with a new filter. Drive
> >it for a bit and see if the higher viscosity oil slows the smoking any.
> >Mark Durham
> >Sent from my Windows Phone
> >From: Jim Simpson
> >Sent: 6/23/2012 11:03
> >To: Virtual Vairs
> >Subject: Re: <VV> Total Seal rings and turbo oil smoke
> >It seems that several people have zeroed in on the Total Seal rings as the
> >most likely cause of the idling oil smoke on my '66 turbo engine.
> >
> >The engine has about 15k on it, having been totally rebuilt as part of the
> >car's restoration.  I did all the wrench work, but I sent the cylinders to
> >OTTO Parts (back when they were still in business) to be bored 0.040" over
> >and have TRW forged pistons fitted.  They honed the cylinders knowing I
> was
> >going to use Total Seal moly rings.  I installed the moly ring in the
> >second groove per Total Seal's recommendations for a turbocharged engine.
> >I did check ring end gaps and groove clearances, but don't ask me what
> they
> >were -- the engine was assembled in the mid-80's and then sat on the bench
> >for years while the rest of the car came together and I didn't take a lot
> >of notes at the time.
> >
> >The engine was broken it driving it to the Lake Placid CORSA convention in
> >'97 (about 600 miles from here).  I kept mostly to two-lane roads so RPMs
> >would be varied and not have to push the engine hard during the break-in.
> >It ran a bit warm, but settled out after the first 500-1000 miles.  Since
> >then it's run well.
> >
> >A few years ago I did some instrumented runs with the engine, measuring
> >fuel/air ratio, throttle position, manifold pressure and RPM.  (I had a
> >four channel analog-to-digital data converter and a laptop.)  Fuel/air
> >ratio was very good, a touch on the rich side as it should be for a turbo.
> >The turbo produced just under 11 psi boost in 4th.  This is with an
> >essentially stock engine other than the .040" bore.
> >
> >I've owned this car since '68 (second owner) and driven it coast-to-coast
> a
> >couple of times.  I've kept records on it all this time.  During the time
> >I've owned it, it has been rebuilt once with stock GM
> >cylinder/piston/rings, the heads were replaced once due to a dropped valve
> >seat, and most recently the complete overhaul.  Oil consumption has been
> >pretty consistent at ~800 mile a quart over all this time which tells me
> >that the majority of the oil consumption has been due to seepage in the
> >turbo.  (At least the oil keeps the valves and cylinder tops lubricated.)
> >Once the engine was broken it, I've used Mobil 1 10w-30 changing annually.
> >(That's changing it about every 1000 mile -- seems like overkill.)
> >
> >Since the oil smoke started up over the last year, I really haven't put a
> >lot of miles on the engine so I can't say with any certainty just how much
> >oil it's consuming right now.  (We drive it to shows and plan to be at
> >Sturbridge this year.)  But it certainly doesn't seem to have made a
> >quantum leap in consumption.  I'll keep an eye on it though and be sure we
> >have several spare quarts with us on the trip to Sturbridge.
> >
> >I guess my next step is to do a compression check to see if that tells me
> >anything.  But if the compression rings are still intact (and I can't
> >imagine they've worn significantly) and it's something like ring flutter
> or
> >that the gaps on the total seal rings have walked their way around into
> >alignment, I'm not sure that would show up in a compression check.
> >
> >Suggestions I've received include changing the timing by a couple of
> >degrees either way and increasing the idle speed.  I'm not sure why either
> >of these would affect idle oil consumption; perhaps there's something
> >strange going on with the rings at particular speeds.  I'll give these
> >suggestions a try as well.
> >
> >Of course there's still the possibility of a bad carbon seal in the turbo,
> >but the opinions I've received suggest that was the problem the oil smoke
> >would get worse at speed.  There doesn't seem to be visible oil smoke
> while
> >cruising so perhaps that rules out the turbo.
> >
> >So that's the progress so far.  An engine tear down is at least two years
> >away short of a catastrophic failure and I can live with the oil smoke for
> >a while.  (It is a bit embarrassing sitting at a stop light with clouds of
> >oil smoke wafting out of the rear...)
> >
> >Any other suggestions or ways to diagnose the problem are more than
> welcome.
> >
> >Jim Simpson
> >Group Corvair
> > _______________________________________________
> >This message was sent by the VirtualVairs mailing list, all copyrights
> >are the property
> >of the writer, please attribute properly. For help, mailto:
> vv-help at corvair.org
> >This list sponsored by the Corvair Society of America,
> http://www.corvair.org/
> >Post messages to: VirtualVairs at corvair.org
> >Change your options:
> http://www.vv.corvair.org/mailman/options/virtualvairs
> > _______________________________________________
> > _______________________________________________
> >This message was sent by the VirtualVairs mailing list, all copyrights
> are the property
> >of the writer, please attribute properly. For help, mailto:
> vv-help at corvair.org
> >This list sponsored by the Corvair Society of America,
> http://www.corvair.org/
> >Post messages to: VirtualVairs at corvair.org
> >Change your options:
> http://www.vv.corvair.org/mailman/options/virtualvairs
> > _______________________________________________
>
>