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Discussion Starter · #1 · (Edited)
Hello everyone,

I purchased a T30 Nissan Xtrail approximately 2 months ago that needed a cylinder head gasket; it was steaming if the oil filler cap was off and had water /oil sludge in the intake duct from PCV oil vapors and moisture mixing; it was also going through engine coolant. Had code P0303 so I pressure tested the cooling system and used a borescope through the spark plug hole of number 3 cylinder and found water intrusion into it. I replaced the head gasket but noticed clean spots on the pistons on some of the edges which can be an indication of oil blowing by the rings and 'steam' cleaning the spots due to oil evaporation from combustion. Another thing to note is that the vehicle did not exhibit a loss of power so the compression rings were likely okay; likely a piston ring to cylinder wall issue. I've had a KA24DE vehicle exhibit this and a friend with a 4 cylinder RAV4 with the same issue.
I also noticed the oil would get very dark with very little driving; drained out almost black after less than 500 km of driving and would go through around 200 mL a week. I tried heavy engine oils just for the heck of it (20W50) to see if it would change, but it went through that just as fast. So after these symptoms I knew the engine would require substantial repairs. The 2nd Gen QR25DE never had the oil burning issues or head gasket issues that the first gens had; the 2nd Gen head gasket have an extra layer around the firing rings. I started doing research at the local self serve wrecking yard buying engine parts, disassembling them and studying their possible compatibility; there will likely be another thread for this later. Anyways, here are pictures from the original engine disassembly. I am rather certain this fate will befall any 1st gen QR and when it does, rebuilding it will be necessary. You can see where the cross hatch of the cylinder wall was polished off and allowed for oil to bypass the oil control rings.
An interesting thing to note is that the oil was kept topped up by the previous owner(s) and no bearing damage was noticed from lack of oil. Distance was approximately 278 500 km. I removed a cylinder head from an L31 Altima at a wrecking yard and it had the same clean spots on the pistons as well. Also, when I checked the oil, the oil on the dipstick would smell like burnt oil.
 

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Discussion Starter · #4 ·
Hi CrickiKaze,

Thanks for additional info. That's one of the reasons I started this post so we can get others' experiences and insights. I have already swapped a 2nd gen block from an S35 Rogue but will make a different post about that.
 

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Discussion Starter · #5 ·
Here are pictures from the cylinder head I removed from a wrecking yard from an 05 Altima L31. Deems like the burnt oil was creating carbon issues which led to valve issues. The tip of the valve stem looks like it was wearing unevenly and the valve head was pitted. I think it over heated the valve and caused the deformation.
 

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