I drive a 2006 Nissan Murano with 204,000 miles on it. I recently had to replace the alternator as oil was leaking out of the front rocker cover which over time killed the alternator. As I did such I noticed also the oil pan on the bottom had become so rusty that it was perforated and leaking. I check my oil frequently and it never ran dry or got close but going through oil quickly I decided to mount a repair. I replaced both the left and right valve/rocker covers with new ones from amazon. At 60$ for the pair with new gaskets and spark plug well seals I was happy. I also at the same time replaced the back pcv valve and PCV hose, PCV hose in between the two valve covers, but not the PCV hose that goes without a valve from the front valve cover to the air intake. I also replaced the oil pan, aswell as had to replace the purge solenoid for the evap system which broke during disassembly of the engine due to brittle conditions of the plastic. During the repair, a small piece of rtv sealant about .5inch round by 1 inch long fell into the drain hole next to the timing case and into the engine. After some internet sleuthing I read not to worry as worst comes to worst it would hopefully just get picked up by the oil filter.
The first start up the engine had no issues and idled perfectly, I topped off the fluids and drove home from my uncle’s garage to my apartment about 10 miles away. The next day I started up noticed no issues and drove to my mom’s home about 30 miles drive on the highway, parking in her driveway on a slight incline with the rear down and front up. A few hours later I go to start the cold car and a huge plume of smoke comes out of the tailpipe, so much smoke I couldn’t see anything for a second, the smoke clears and the engine ran fine so I decided to ignore it and drive to my dad’s house about 5 minutes away. A few hours later I go to start the car on his level driveway and have no smoke, I drive 30 miles home and park for the night. This morning I go to start my car and another huge plume of smoke, I checked the oil and saw it was a little low so I topped it up. When I started the car arriving at the store no smoke. Now cut to just now and I had to swap cars around with my roommates and another huge plume of smoke from a cold startup.
I’m a young mechanic and it’s certainly possible I messed something up but for the life of me I can’t figure out what. So far I have 3 leading theories but would appreciate any advice or things to look for. Theory 1 is that the valve gasket somehow rolled or the mounting pressure wasnt applied right and somehow there is a leak causing excessive oil consumption. Theory 2 is that not replacing the front PCV hose has cause some sort of vacuum leak causing an imbalance in the PCV system’s vacuum pressure causing the PCV valve to remain constantly open causing the excess oil consumption. Theory 3 and the one I hate the most is that somehow that little piece of it has managed to position itself perfectly to clog an oil drain in the area around the valves. With nowhere for oil to drain it pools up on the valves after running and drains into the cylinders through slight leaks in the valve stems. Please let me know what you think and if you have any suggestions on where to look.
I’ve attempted to include a photo for clarity. I replace the PCV valve and PCV hoses 4 and 8 but not hose 1. I did not use any rtv on the valve cover gasket as it asks you to do so in the photo. Potentially theory 4?