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lashcap lashcap is offline
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Join Date: Apr 2007
Posts: 4
`86 930 w/ ITS Turbo-Cooling Issue


I am playing with an `86 930. It is a 3.6L now and it has this funny
setup I thought I would share with you all to illicit some input as I am fairly ignorant when it comes to turbos.

Oil is fed to the ball bearing of the F2 ITS turbo in the way that you would expect from a Porsche. Oil passes through the bearing, ends up in the small oil reservoir and is scavenged by the oil pump at the back of the camshaft.

Here is where it starts to get interesting. Instead of that oil being pumped back to the oil tank, it is sent forward again and pushed through the turbo water cooling section in an attempt to cool the turbo. Oddly enough, the "water" outlet which is now flowing oil is carried by a rubber hose directly into the chainbox cover. Needles to say, the blue rubber was scorched brown and failing.

The best part is this. There is a dash eight line connected to the small turbo oil reservoir which travels towards and is connected to the drain plug of the engine--from there it immediately goes to the scavenge pump at the back of the engine.

I would appreciate any corrections in my terminology.

I ran a 3.2 once on a hoist, idling, raised it in the air and pulled the drain plug--no oil came out. This was my introduction to the scavenge side of the oil pump and the beauty of dry sump. This car has a GT3 oil pump.

This turbo had 2000 miles on it and failed. The shaft wobbled excessively in the turbo.

My theory of course is that the scavenge pump at the back of the motor is actually sucking air from the bottom of the case instead of oil, thus no oil cooled turbo instigating a quick failure.

Any thoughts? Thanks in advance.

Last edited by lashcap; 06-01-2007 at 11:18 AM..
Old 06-01-2007, 10:24 AM
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