Sometime ago we discussed the importance of the oil drain back
from the turbo. The oil was described as a white foam and a half
inch to 3/4 inch pipe was necessary to drain it back successfully
despite the feed pipe being only 3/16 to 1/4 inch in diameter.

I find it interesting that Mazda discovered a lot
of the problems with the turbo drain back oil were generated
AFTER the oil left the turbo bearing housings. Apparently
the radiant heat from the cherry red turbine housing was
cooking the oil in the drain back tube. Here is the 87-88
compared to the 89-92 drain back pipes. Note the heat shield
on the 89-92 pipe. I have a 87 engine with a 91 turbo
so I need to use the larger diameter 87 drain back pipe.
The 87 pipe fits the  91 turbo fine so I will move the 91
heat shield to the 87 pipe.

If you are using a TO4 be sure to shield this drain back pipe from the
tremendous radiant energy of the turbine housing.

Paul Lamar

Rino Lacombe wrote:

Thanks for the info Paul, I have exactly the same turbo setup as you have.

Rino

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