<VV> Total Seal rings and turbo oil smoke

[Jim Simpson]

I've gotten very used to modern cars with near zero oil consumption.  But
with the Corvair, I'm also used to it's need for oil every 4th or 5th tank
of gas.  It's just the newly developed, but occasional, "mosquito killing
clouds of smoke" that offends me.  (I don't grieve for the dead mosquitoes
though!)

For the first 100k miles on the car, I didn't know about the need for
cool-down after hard runs but it survived just fine.  When I overhauled the
turbo, it was remarkably clean; some coking inside the exhaust turbine
housing, but the bearing assembly and compressor side were almost like new
with all clearances at factory spec.  I guess the frequent oil changes (and
constant feeding of fresh oil) helped.

Since the car's restoration, it's been much more gently driven, though the
turbo has been used on occasion -- with cool-downs -- and its been feed
synthetic oil so I doubt there's any significant coking going on.  I'm
going to just put the current problem down to the carbon oil seal aging
until I get the time to pull it apart.

So I think it's appropriate to close this discussion for now.  I'll post
new info if something develops.

Thanks everyone for the suggestions!

Jim Simpson
Group Corvair

On Sun, Jun 24, 2012 at 4:32 PM, Mark Durham <62vair at gmail.com> wrote:

> Jim, if your compression is that good and even, that should indicate the
> problem is not rings. I'm pretty confident that you have zeroed in on the
> correct place, the turbo. I've never owned a turbo corvair so have no
> experience with oil consumption however the turbo aircraft engines I used
> to maintain always used more oil than their normally aspirated
> counterparts. I was comparing to my recent 110 rebuild .030 overbore and
> chrome rings. I saw 1/4 quart use on the straight 30 wt breakin oil for the
> first 500 miles, changed the oil and filter to a 10w30 and it has not used
> a drop 800 miles later..
>
> And we didn't think to much about a little smoke out the pipe at idle on
> the turbo aircraft engines unless it was steady. The seals will leak
> because they can also get coked up , dirty from deposits, over time and
> some may clean out with consistent driving, others may not.  Go put some
> miles on it with the turbo working.
>
> Mark Durham
> Sent from my Windows Phone
> ------------------------------
>
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