So my wife's 2002 Corolla just hit 100k miles after 14 years of reliable short-tripping. After an oil & filter (M1 HM, Puro Synthetic) change and a new air filter last week, I decided I really needed to address the leaking valve cover gasket and change the original plugs. That's the part that always scared me, not being sure if the original plugs would come out without a fight. It didn't start off too well as the cover gaskets were stuck to the head. The main outer gasket was peeled off in one shot but the plug tube gasket o-rings turned hard and brittle and they eventually came off in pieces. I had to be VERY careful I din't drop any into the engine but luckily I got all the old stuff off and cleaned the mating surfaces. I didn't take any pics since it looked exactly like I expected: varnish from years of short tripping but otherwise fine with no sludge to be seen. The chain was tight and the cam lobes looked perfect.
The plugs were next. I said a quick prayer to the FSM and gave the first one a tug. Miracle of miracles, the plug popped loose easily and came right out. The other three followed suit. Maybe NGK and Denso are right about plated plugs not needing anti-seize after all, but I still put a little bit on the Denso Iridium Long Life replacements. One strange thing about the plugs, the manual calls for them to be gapped to .044" but they all came out of the box at .039". Knowing you're not really supposed to re-gap Iridium plugs, I did it anyway and got them all perfect. The strange part is that the original plugs that came out were all over the place: .036", .037", .040" and .041". I'm not sure what to think about that because I assumed the gaps would have opened up over time if anything. The car runs fine, nice and strong, so I'm not going to worry about it especially since they are gapped correctly per the manual and the hood sticker.
Next was a drain and fill for the transmission, using about three quarts of MaxLife Dex/Merc. I've done this a few times before, maybe once every 10k miles, and it really makes a difference. The transmission shifts perfectly, nice and firm.
Things I skipped (for now): The timing chain tensioner is a known source for leaks so I bought a new one, but it's in a not easily accessible place and I didn't want it to ruin my afternoon so I dropped it. Same goes for the O2 sensors as the pre-cat sensor is in a bad place, and the post-cat sensor did not want to come out. And I'll get the brakes re-bled at some point. And the coolant changed, and the hoses, and the thermostat...
The plugs were next. I said a quick prayer to the FSM and gave the first one a tug. Miracle of miracles, the plug popped loose easily and came right out. The other three followed suit. Maybe NGK and Denso are right about plated plugs not needing anti-seize after all, but I still put a little bit on the Denso Iridium Long Life replacements. One strange thing about the plugs, the manual calls for them to be gapped to .044" but they all came out of the box at .039". Knowing you're not really supposed to re-gap Iridium plugs, I did it anyway and got them all perfect. The strange part is that the original plugs that came out were all over the place: .036", .037", .040" and .041". I'm not sure what to think about that because I assumed the gaps would have opened up over time if anything. The car runs fine, nice and strong, so I'm not going to worry about it especially since they are gapped correctly per the manual and the hood sticker.
Next was a drain and fill for the transmission, using about three quarts of MaxLife Dex/Merc. I've done this a few times before, maybe once every 10k miles, and it really makes a difference. The transmission shifts perfectly, nice and firm.
Things I skipped (for now): The timing chain tensioner is a known source for leaks so I bought a new one, but it's in a not easily accessible place and I didn't want it to ruin my afternoon so I dropped it. Same goes for the O2 sensors as the pre-cat sensor is in a bad place, and the post-cat sensor did not want to come out. And I'll get the brakes re-bled at some point. And the coolant changed, and the hoses, and the thermostat...
