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As most of you know, I'm near the end of my S2 conversion but have been struggling to try to solve a foaming oil problem of late. Today I replaced the 1.8 bar oil pressure sender, de-skinning every one of my knuckles in the process. Also removed and inspected the oil pressure relief valve, which looked fine and wasn't seized or installed incorrectly.
I then started taking a closer look at the turbo, pulling off the intake hose from the cold side. To my surprise, the turbo does not spin freely by hand. It turns, but does not spin. I can turn it with one finger on the blades, but there's resistance there. Aren't turbos supposed to spin freely? There is zero end-to-end or side-to-side play in the shaft. I first noticed this condition when I tore the engine down and rebuilt it. But I figured that it was a little tight because it hadn't had oil in it for a couple of years. However, now that the engine has run and oil has (presumably) circulated, one would think that the turbo bearings would be lubricated enough to spin freely. Could this resistance be blocking the flow of oil into and out of the turbo? Could this be causing the foaming oil in the oil pan? My gut feeling says yes. So I spent the rest of my day removing the turbo (I love undoing what took hours to do) so I could open it up and see if I can see a blockage of some sort. I also noticed when I was removing the turbo that there was less than about 1/4 teaspoon of oil that came out of the turbo and it's oil feed and return lines, which I found to be quite strange. The 1.5 liters of coolant that spewed out of the coolant return line more than made up for it though. Makes for a nice, greasy garage floor.
Anyway, what do you guys think? Does this sound plausible?
I then started taking a closer look at the turbo, pulling off the intake hose from the cold side. To my surprise, the turbo does not spin freely by hand. It turns, but does not spin. I can turn it with one finger on the blades, but there's resistance there. Aren't turbos supposed to spin freely? There is zero end-to-end or side-to-side play in the shaft. I first noticed this condition when I tore the engine down and rebuilt it. But I figured that it was a little tight because it hadn't had oil in it for a couple of years. However, now that the engine has run and oil has (presumably) circulated, one would think that the turbo bearings would be lubricated enough to spin freely. Could this resistance be blocking the flow of oil into and out of the turbo? Could this be causing the foaming oil in the oil pan? My gut feeling says yes. So I spent the rest of my day removing the turbo (I love undoing what took hours to do) so I could open it up and see if I can see a blockage of some sort. I also noticed when I was removing the turbo that there was less than about 1/4 teaspoon of oil that came out of the turbo and it's oil feed and return lines, which I found to be quite strange. The 1.5 liters of coolant that spewed out of the coolant return line more than made up for it though. Makes for a nice, greasy garage floor.
Anyway, what do you guys think? Does this sound plausible?