01 Prerunner 3.4 Motor Noise

I have a 2001 Prerunner with the 3.4 and automatic tranny. It just started machine some tapping noise last week. I have done some reading on hear and I see that a common problem is the flex plate. When you put it in gear and accelerate the noise stops or almost doesn't exist anymore. But when you take your foot off the gas and it comes back. Depending on how fast you are going it is loud and quiets down as you coast to a slower speed.

Is the flex plate the flywheel or the drive plate?

Any help or point in the right direction will be greatly appreciated.

Thanks

 

Is it a pinging sound? Might not be a bad idea to record video so we can get sound.
If you suspect an issue with the transmission I would get that into a shop asap. They should be able identify the problem fairly quickly and give you an idea of what you're up against.

 

I just went ahead and dropped my oil pan. It has gold flakes in it which tells me I have a failing rod bearing(s) correct? I just don’t understand why it would not be a constant sound..

Can I replace the rod bearings from the bottom and not have to pull the pistons from the top?

 

I would pull the center main first and take a look, the damage might not be to just the lower rod bearings. When you do start pulling rod caps off do it one at a time and keep looking for the one(s) that is worn through to the brass. If you dont find one then the wear is in the piston pins... that brass has to come from somewhere. I dont remember if Toyota uses a bi-metal (babbit/steel) or tri-metal bearing(babbit/brass/steel) , its been a while.
If your fingernail hangs on any portion of the crank journal when you scratch it across it it is too rough and you will wipe out the new bearings pretty quickly.

 

I know its been awhile since I have responded, but I did want to share what I found. My flex plate ended up being cracked. In fact it was so bad the crack went completely around where it bolts to the crankshaft. Only a small piece was still hanging on.. As for the flakes in the pan I still do not have a clue. All of the rod bearing and end caps looked good. I put everything back together, changed the oil filter and added new oil. Checked the pan a week later and everything was how it should be.. Thank you for the help and ideas.

 

thanks for the update... you wouldn't have a video/audio recording of it running with the bad flex plate do you?