I know the HG is pretty much always it, please spare me any lectures on this LOL. If my post history is visible going back 5 years or so, you should find posts where I replaced the engine in my '13 Prius V at around 390K miles - used a low-mileage JDM engine while at the same time replacing the intake manifold, water pump, T-stat / housing, PCV valve, radiator cap, plugs, etc with new and cleaning the new engine's EGR cooler and pipe ultrasonically (they were in great shape even before cleaning). The original engine was an oil-burning, blown head-gasket-having, mess of stop leak. I scrapped it after transferring needed parts over to the JDM replacment. This new engine always needed very slight top-offs of the coolant tank at oil changes. It'd be about a half inch below the fill line every 5K miles. Did not burn any oil. Fast-forward to the present day. At 490K miles, my wife and I gave this Prius V to her sister, who continued driving it. About a month ago, it started blowing white smoke like a blown head gasket and losing coolant. It got parked for a bit. At no time did it do the rough start-up typical of a head gasket problem. My bro-in-law took it to a buddy of his who works on Priuses, and today they tore it down expecting to find a blown head gasket. Instead, they found signs of coolant in each cylinder. The exhaust manifold is wet at each port. They say the head gasket looks fine. Besides the EGR cooler and the throttle body, are there any other potential paths for coolant to get into the engine? The head and block are both flat and show no signs of cracking. They pressurized the EGR cooler and put it in a bucket of water, no bubbles. Pressurized the throttle body coolant passages, no sign of leakage. Other ideas are welcome. I'm not there to verify a lot of this, but my brother in law and the guy he's working with are both pretty smart guys, not their first rodeo. The pictures I saw show some rust on the tops of each piston, it's equally spread. The spark plugs all look the same. The exhaust manifold port entrances are all equally wet. Just seeing if there's anything out there that could've been missed.
Perhaps internal engine damage which is allowing seepage of coolant in the block into the cylinders? Granted I know very little about the internal mechanics of the engine, but if you haven't found any other evidence of coolant coming in from other parts, then could this be a possibility?
