Evader53

Howdy...

I recently purchased a 2004 Tacoma TRD SR5 V6 (3.4L) and it has developed a knocking in the engine. A mechanics stethoscope has been used but its extremely difficult to pinpoint where its coming from.

I know that Tacoma's typically have a louder idle & valve noise, but this is not that at all (listen to clip below). The engine only has 47k miles on it and the timing belt, water pump, and serpentine belts were replaced at 46k (due to a leaky water pump).

The engine has been meticulously maintained and the truck was never beat on.

The "knocking" only occurs when the truck is in drive or reverse, at operating temperature, at RPMS less than 1200, and is even more audible when the A/C is on. So its something that occurs only when a load is placed on the engine.

The truck still drives great and sounds perfectly normal above 1200 rpm.

Here is a link to the sound:
http://www.youtube.com/watch?v=qWnBI...1&feature=plcp

Please let me know what you think

ksti

My ears tell me that's doesn't sound like a knock, more like a scraping, but without being there that's just guessing. Sorry i'm not more definite. If it is a rod knock you should still be covered under your drivetrain warranty or it's possible something was not done right when previous service was done. Either way I would take it back where it was last serviced being only 1k ago.

rworegon

Flex plate comes to mind:
https://www.yotatech.com/forums/f116...-knock-233278/

Evader53

Pistons are very clean, thrust bearing is w/in spec, and knock is still there.

Seems to be loudest around oil pan drain bolt area...
You can feel it the thump slightly in the shifter when sitting in the cab and in drive w/ a/c on.

vital22re

iTrader: (2)

if auto..... flex plate

Texas_Ace

Ditto above, sounds closer to a cracked flex plate then an internal knock. Sounds like a scraping sound, that would also explain why the stethoscope can't track it down.

drpdmazda

sounds very similar to the nightmarish cracked flexplate sound i just dealt with. there is an inspection plate that you can remove and look at the flex plate, but in mine you could not see the crack until it was out.