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Iowa | Here's what we have seen just a very few times on a CAT 3406 engine(wet sleeve engine) with only oil in coolant and new oil cooler. The culprit was caviaton erosion(pinhole) behind the upper o-ring of the bottom three o-rings at the lower end of the liner. When the piston and oil scraper ring would get to the bottom of its stroke, the oil being scrapped off of the liner(by the ring) would have just enough pressure to push oil, into that pinhole, into the cooling system (from behind that top,lower o-ring), THEN the coolant pressure would push against that top, lower o-ring(covering the pinhole) and coolant WOULD NOT enter the oil pan. You could not find this problem by removing the oil pan and pressurizing the cooling system. The engine liners were removed, o-rings were removed, then flat plates w/rubber were put on the top and bottom each liner and clamped in the hydraulic press and we pressurized the plates(with a fitting and shop air). Used soapy water and squirt the sides of the liners where signs of pinholes were starting, while under pressure. This is how we found this problem. New liners (AND coolant conditioner) cured that problem. I'll admit this is an unusual problem; where the fluid only transfers one direction. | |
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Oil in water. Where to start?
