Hello all,

I've owned since new a 2006 Honda Accord 2.4L (K24A8) sedan 180,000 highway mi., always Mobil 1 synthetic oil every 5-7K. Started excessive oil use around 70K, now using 2 Qt every 500 mi. The cam chain jumped several teeth at 160k and bent 4 intake valves. Had head professional rebuilt, new seals, bent valves replaced, all valves and seats reground, head checked and machined, valve clearances set to spec. After reassembly, oil use continued, thus planned to replace piston rings (assumed stuck or poor sealing oil control rings) in the Spring. Recently while traveling on the interstate the engine lost compression on #3. Pulled head and found 1 burnt exhaust valve, not sure why (approx. 20K on head rebuild). Recently pulled pistons (removed oil pan while still in vehicle), all rings appear to be free in their grooves, oil rings are expanded slightly beyond piston surface and can see light thru drain holes in oil grooves. Cylinder walls look fine and all bore gauge dimensions are well within service limits per Honda service manual. Pistons measure within service limits as well, though one is at the lower end. Black wear area on piston skirts have mid and lower areas worn thru but some of the black remains. (see images)

I'm hoping to get another 50-100K out of the car which will be used by my 15 year old daughter. To keep the budget down, I was thinking i'll thoroughly clean the pistons and re-ring with new NPR brand rings (Honda motors can go many hundreds of thousands without rebuild). I considered replacing the pistons with reasonably priced Evergreen brand made in Taiwan. However, thought I'd stay with my orig. Honda, new Honda too pricey. I'll leave the block as-is, Honda service manual states not to hone cylinder walls unless scratched. As for the head, I'll have the engine shop replace the burnt valve. The rod bearing seem to be in good shape, I'm considering re-using these.

Does anyone have any comments or insight on my plan of action or why the motor uses so much oil? Burnt valve? Reuse rod bearings?

Any sound advice for this shade-tree mechanic would be greatly appreciated.

 

Your plan sounds reasonable.

You can replace rings with out the need to rehone or bearing replacement(make sure the bearings go into the same cylinder they came out of) Do not do anything to the cylinder walls,other than wipe them down with a lint free cloth.

From the pics of the combustion chamber, you're definitely leaking oil in to it. If all of the pistons look like the one pictured,I suspect a poor valve job is the culprit.

The burned valve may have been the result of improper valve clearance after the valve job or some other assembly error.

 

Thank you DCFIVER. I did keep track of the bearing locations. I set the valve clearances, could have made a mistake (though I did take my time and double-checked each clearance after locked). Wish I'd found something more obvious causing the excessive oil use.

 

i once bought an old motorcycle with a burnt valve. The seat still looked good so I went to the dealer and bought a brand new valve. I installed it and checked the valve seat for a complete seal with a flashlight and then did a fuel hold test. It was all good. Put it all back together with the new valve and the bike rode like a champ. Rode it like this for a year then I sold it.