After a nice week of the van running sweetly, I developed a really loud metal clanking sound in my exhaust system yesterday on the way home from a lake. The problem started at freeway speed and continued at idle. The metal clanking sound is so loud that it drowns out the sound of the exhaust system. It is erratic and varies with engine speed. I drove the van for another 30 miles home with no adverse effects. I thought that maybe an exhaust valve broke off and was rattling around in the exhaust pipes. Or, maybe a piece of catalytic convertor was caught in the muffler. Sounds like a piece of metal is caught in there and banging away really lound. I'm not talking to about a gentle, "tick, tick" or even a "clank, clank." this is like CLANK!! TICK, tick, CLANK!!, TICK! Audible at thirty yards over the sound of the engine. I took off the U-shaped pipe that connects the header collector to the catalytic converter. There was no metal in there. The cat side that is facing the O2 sensor looks solid. I haven't disconnected the cat from the muffler yet. I took the valve covers off and valves appear to be moving. For about 1 year, I had a malfunctioning lifter on exhaust valve on cylinder 3. I now believe that this caused a range of problems, including a ruined O2 sensor. (two different mechanics in my area didn't diagnose the problem correctly and I didn't have enough knowledge). After I replaced the lifter, it wasn't adjusted properly. I just adjusted it properly about 2 weeks ago. I was thinking that maybe something broke. If an exhaust valve breaks, what are the symptoms? Again, I had adequate power on the way home. I have a spare exhaust system and almost near cylinder head. Right now, I plan to swap in a used U-pipe, cat, and muffler combo and see if that solves the problem. If that doesn't work, I'll ask more questions. If I have to, I can swap out the cylinder head too. I don't want to go through that hassle, but I a am prepared to do it this weekend if it will get my van on the road. The van is on jack stands again. At least it got us home. It somehow always gets us back. :-) Any advice on the sound would be appreciated. |
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