"plastic" sounding engine knock

Hey guys,

Have a 2013 with about 18,000 miles on it. I've noticed lately, that sometimes, the conditions seem to have to be just right, the engine makes a strange, plastic sounding knock that is in-tune with the engine's rpm's. It's right around 35-45 mph, with very light throttle. (I accelerate like a grandpa sometimes)

It's like a piece of thick plastic is being flicked by the pistons or something. (I know there's no plastic IN the motor...just what I can come up with to describe it).

2013 4x4 TRD Sport Double Cab.

Everything is stock.

Ideas?

 

Tape flap from a wire harness under the hood and or your rubber fenderwell engine bay curtains has come loose.

 

I had something similar and found out it was the hose clamp at the top/back of the engine. The clip on the bottom I guess had broken somehow and it would rattle against the firewall at certain rpm's and at a stoplight with my foot on the brake. idiling in neutral or without my foot on the brake didn't cause rattling though.

just look around the area that it seems to be coming from and you can probably see something. Like you said, there isn't any plastic inside the engine so you should be able to find it with some investigation.

 

I'll check out these ideas when I get a day off work and back to you all. Thank you for the suggestions.

 

You may be imterpreting that plastice sound as engine knocking. Try a high/premium grade gasoline on you next fill up to see if it goes away, if so, that is a normal 'problem'.

 

I've heard engine knock on my old truck, but I don't know if that'd be it. It's just so sporadic. Still haven't had a chance to poke around under the hood and through the wheel well to check things out.

 

I was able to capture a little of the sound on my phone. You have to turn up the sound on your computer pretty good to hear it, but it is much louder in person. My wife was in the truck one of the last times, and she heard it too.

Guess I'll be taking the truck in soon.

I saw another thread by hotrod about his engine creating a bad noise. Anybody think this sounds like the same?

Ideas on the sound? It only happens when it is freezing or below freezing...so far.

 

Oh trust me...radio is up in most cases. I don't think I'll be able to take it in for them to hear it until it gets cold here again next fall, as it only seems to happen in the colder elements.

It does make the sound even after the engine has warmed up. That recording was taken after about 35 miles of driving...and I don't move my truck until the temp guage gets over the cold line.

Wish my phone was able to get a louder recording of it.