Hi all,
I acquired an '04 Platinum Edition Pathy in September. She had a noticeable oil leak, so I immediately set about trying to track it down. I found serious oil leaking around the crankshaft position sensor. I replaced it, hoping the issue was just the gasket, but it was still leaking. I drained the oil, dried everything off, put a larger gasket around the upper housing of the sensor, then used JB Weld to seal the whole thing up. Problem solved!

Not so much. There was also a weird little 3/4 inch long gap at the bottom of the crankcase, near where the sensor was located. I ended up doing the same thing here - I drained it, cleaned it up, and sealed the spot with JB Weld. Not a drop of oil coming out of there to speak of.

Still, I had a leak. I did some searching on various forums, and the consensus seemed to be that the valve cover gaskets were the most likely culprit. I ordered a set of gaskets online, watched several YouTube tutorials, and finally steeled up my courage to take the top of the engine apart.

After twelve hours of work, what had been a minor leak turned into a gusher. On my first test drive, the smell of burning oil flowed into the air vents, and I could see the smoke coming out of the engine bay. I realized I'd screwed up.

Yesterday, I took it all apart again, and found what I'd done: one of the gaskets hadn't seated correctly, and about an inch of it was not in the channel. Problem recognized, new seals installed, everything torqued to the specs in the Chilton's guide, everything buttoned up.

I'm back to my original leak, which tells me it must not have been the gasket seals. So, any other thoughts for a weekend wrench turner who would really like to track down this mystery leak?

VQ40's can sometimes get wonky leaks at the back of the upper oil pan or inside the valley that are very hard to find. Invest in a UV dye set and put a few teaspoons in the oil, the dye won't lie. Unseal that raggedy notch in the bellhousing, too. That's a drain, it isn't supposed to be sealed up.

Thanks for the info. I'll get the JB Weld out of that drain, and get some of the UV stuff as well. Where exactly is the drain supposed to be draining? In guessing the oil I found in it was not actually coming from the drain, then?