Suspect head gasket failure at #4 cyl. due to coolant on cylinder walls and in tail pipe. Also possible piston ring failure due to low compression in #4 and oil fouling on spark plug. Compression and spark plug in adjacent cyl #5 are normal. The only sign something was wrong before the tailpipe smoke was about two days prior - engine ran rough for about 20 seconds at a stoplight, then cleared. Triggered a P0304 (misfire in #4 cyl) engine light. Ran fine next couple of short trips. Third time startup, lots of smoke/coolant vapor at tailpipe, although engine idled fine and did not overheat. Maintenance is always done regularly and nothing but synthetic oil used.
I've read more than a few descriptions of the same problem in the #4 cylinder of the 3.5L V6. It is sounding like there probably is a flaw either in design or casting of the block and/or cylinder head that is causing the same problem in so many of the same engine. I've read comments of individuals contacting Honda Corporate to complain and getting blown off. Sounds like there will only be decent recent response from Honda if there is a class action or extreme broadcast media attention.
A trusted mechanic is diagnosing but has not concluded what the exact problem is so I don't know what the proper repair will be or the cost.
Suspect head gasket failure at #4 cyl. due to coolant on cylinder walls and in tail pipe. Also possible piston ring failure due to low compression in #4 and oil fouling on spark plug. Compression and spark plug in adjacent cyl #5 are normal. The only sign something was wrong before the tailpipe smoke was about two days prior - engine ran rough for about 20 seconds at a stoplight, then cleared. Triggered a P0304 (misfire in #4 cyl) engine light. Ran fine next couple of short trips. Third time startup, lots of smoke/coolant vapor at tailpipe, although engine idled fine and did not overheat. Maintenance is always done regularly and nothing but synthetic oil used.
I've read more than a few descriptions of the same problem in the #4 cylinder of the 3.5L V6. It is sounding like there probably is a flaw either in design or casting of the block and/or cylinder head that is causing the same problem in so many of the same engine. I've read comments of individuals contacting Honda Corporate to complain and getting blown off. Sounds like there will only be decent recent response from Honda if there is a class action or extreme broadcast media attention.
A trusted mechanic is diagnosing but has not concluded what the exact problem is so I don't know what the proper repair will be or the cost.
- Ron N., Huntington Beach, CA, US