Mark :
I've seen this condition (excessive blowby with good performance) on many high
mileage engines (including most of my current vehicles <g>). Typically, the
excessive blow-by only happens under heavy load/acceleration (eg freeway
on-ramps)
when peak cylinder pressures are high for a long time. Smoke from the exhaust
is
caused by oil getting past the rings (or valve guides) into the cylinder. Since
oil is thicker and has less pressure on it, engines can have excess blowby for
a
long time before they wear enough to burn oil and smoke. (I live in CA, where
smoking is a capital crime for a car <g>)
Your mechanic is probably right about the rebuild, especially if you are seeing
blowby (that oily exhaust stuff) from the oil filler. If you do have it
rebuilt,
be sure to get one of the lip-seal conversions for the rear main seal. They are
much better than the original factory labrynith seal and will actually tolerate
some crankcase pressure without leaking.
For workarounds, try going back to a breather oil cap, or even a free-er flowing
arrangement like a foam filter as a cap (performance shops sell these). This
does
nothing for the real problem (worn rings), but might reduce oil blowing past the
rear seal.
IMHO, PCV systems should have a fresh air intake anyway, to dilute the blowby
gases and reduce acid formation. Later American cars do this (I'm not sure
about
later TR's).
Randall
Mquinn698@aol.com wrote:
> I have a TR4A that has the typical oil leak. I read that a bad PVC valve can
> cause that engine gas can force oil out of the seals. I replaced the PVC valve
> and hoses. The problem is the engine build up so much pressure that it blew
> oil out of the PVC valve seal. The car is now in the shop and I am being told
> that the engine will need to be rebuild because there is too much blow by in
> the rings. I trust the mechanic but it seems to me that if that much gas was
> getting past the rings that the car would be smoking like mad. The car only
> seems to smoke intermittedly as though only when it vents engine gas. I did
> also replace the breather oil cap with a non breather type (the correct type
> for TR4A closed system) with the breather cap on when driving the car you
> would get out smelling like oily exhaust. The engine runs very strong in every
> other way. Anyone have any suggestions.
> --Mike Quinn
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