I have a 1998 EJ6 Honda Civic LX D16Y7 Autotragic Tranny with 210k miles and pretty much as long I have owned it, I've had a "mystery oil leak". I finally narrowed it down to the internal seals by the timing belt (which I'll change when I do a timing belt & water pump job) and the oil pan gasket.
Simple enough I figured buy the gasket, start the oil change I needed to do anyway, drop the pan, replace the gasket, and put it all back together. I even have the Factory Service Manual and the generic version of HondaBond (Permatex Ultra Grey). After reading over the FSM pages repeatedly and printing them out I started on it yesterday afternoon Felpro Permadry Plus gasket in hand.
Drained the oil. Changed the filter., Dropped the pan, and found out I had to disconnect part of the exhaust (where the pipe connects to the bottom end of the cat just after the 2nd o2 sensor) to get it free so got out my battery powered impact and did that. Cleaned off the old mushroomed ancient gasket as best I could and hit it as well as the inside of the pan with copious amounts of brake cleaner to ensure there wasn't any particulate left in the pan. Wiped everything off with cloths and then started reassembly, putting grey RTV in the places indicated by the shop manual printout, putting the new gasket in place, etc.
I got everything back together except for 2 bolts on the pan finger tightened before it got too dark & cold to continue working. This morning I got up early to finish and make it to work on time. Put the last 2 bolts back in the drain pan, snugged everything up with a criss-cross pattern (sorry no torque wrench) ensured the new filter and drain plug bolt were also secure one final time and filled it up with what I thought was 3.75 qts of 5W-30. Checked to ensure there were no leaks. No leaks seen.
Then things went sideways-as soon as I fired it up I heard an awful loud knock from the lower end so I immediately
cut the ignition and went to double check the oil. I realized I'd not filled it up completely and put another half quart or so in, until the dipstick read FULL. I work as I tire and lube tech for WalMart currently so I promise I know how to change my own oil
Cranking attempt number 2-engine started and still had a very subdued lower end noise, almost sounded like a valve tick except it didn't start until I shifted into reverse and was coming from the lower end. Stuck my head under the vehicle and it was loudest and most pronounced under cylinder 3/4 where the engine mates to the automatic transmission. It would get louder with increase in rpms and STOP when the vehicle was in park or neutral at idle. At this point I cut the engine back off and decided to start over from the beginning.
Drained the new oil into a container, and dropped the pan again to check for any damage and looked for any metal shavings, as well as felt "up" the con rods, around the crank journals, basically any thing I could get my tiny fingers on/in/around. And yes I didn't see anything in the pan after thoroughly checking. No damage, no chipping, no signs of any metal debris/shavings to be seen or felt ANYWHERE. Sealed everything back up again, filled it back up with the new oil and fired it up again.
Again the pinging or ticking almost like a valve noise except coming from the LOWER END. And even quieter this time. So I figured I MUST have done something wrong and set out to my local mechanic. The noise would increase and sound almost like a buzz saw NOT a thumping, but I finally noticed it would increase in pitch and volume with the RPMs until the transmission shifted into the next gear and then would get silent. Got to the shop (2 miles away at low speed) and found out they couldn't get me in until Thursday. At this point I'd already lost today's workday and am not keen on losing 2 more. I dropped the pan for a 3rd time checked everything over yet again this time using my phone as a light due to the lateness of the hour and again no signs of damage. Finally sealed it all back up one final time and called it a day letting it cure overnight.
So what gives? Does anyone have any ideas?