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Jim Grant's Tech Tips
94
Toyota Supra TT, Big Time Smoke Screen
Q: I
have a ‘94 Toyota Supra twin turbo. I bought the car salvaged with 52,000
miles on it and I thought it was a good deal. But as soon as 53,000 miles
came on, it gave me the biggest headache ever. There was smoke coming
out of the exhaust. When I say smoke, I don’t mean little puffs, I mean
tons and tons, even to the point where you can’t see what's behind you.
Now there is oil coming out the exhaust along with the smoke. The engine
won’t go any higher than 3000 RPM’s and it makes a hissing noise. Got
any suggestions? The Toyota dealership said it was the turbos, but I don’t
believe them.
A: It
sounds as if the dealer is telling it to you right. Your description of
power loss and heavy smoke from the exhaust is a good indicator that one
of the turbo’s oil seals has failed. The turbos have engine oil pumped
to their bearings for lubrication and cooling. Because of their location
if the oil seal for the bearing fails it will pump engine oil into the
turbo housing. Usually the oil seal that fails is on the intake side of
the turbo. This type of failure is reasonably easy to identify by the
amount of oil found in the air tubes from the turbo to the intake manifold.
That is where the easy part ends and the check book goes to work. Do not
try running the engine with a failing turbo. The oil being pumped into
the engine can damage the oxygen sensor, catalytic converter and possibly
the engine if it should run out of oil. One last note, if you do have
to replace one or both turbos, be sure to replace the oil feed lines.
They are notorious for becoming restricted and choking the oil supply
off to the turbo which equals early turbo failure.
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