Loud KNOCKING at start. Quieter when warm.

T

Timmel

Member
Car
2005 FX35
Name
Timmel
Just changed oil on my immaculately kept 2005 FX35 with 116K miles. Drove fine. Two undriven days later, at startup, very loud clatter (KNOCKING). Scarry-loud. Stopped engine. Started again. Same. Loudest near passenger side of engine. Not valve train noise like with low oil. Deep loud KNOCKING sound directly related to RPMs. Get's much quieter, as engine warms. At operating temperature it goes away for a second or two on the down-side of a short rev, returning immediately at idle. Some say Fuel Line associated. Others say timing chain tensioner (but, I don't notice the classic rattling sound of timing chain issues, nor is it loudest in the front of the engine.). This engine has Never had an issue, other than this engine's characteristic use of oil between changes. Ergo, I'm 15 years out of practice in diagnostics. Best ideas ? Thanks for the time.
 
Late response, curious what you found. My FX45 had the harmonic balancer/crankshaft pulley come apart. Sounded like I threw a rod. Got a replacement for the yard, and runs great now.
 
The harmonic balancer/crankshaft pulley came apart/separated. It may look intact, but if it slips just a little it can destroy the motor. It sounded like I threw a rod. Got a replacement from the junkyard, and runs great now. Apart from that I do occasionally get the initial knock when not started for a while that goes away in a few seconds. 150k miles.
 
Less moving parts for sure. But as long as driving feels like a sport to me, I have to feel the visceral growl of the V8. I recently upgraded to a low mileage 2010 FX50S. Probably one of my last cars, and worth the wait.
 
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