Knocking sound coming from somewhere at about 1000 rpm.

This has been going on for a few months and seems to be getting worse. Has anyone ever had knocking sounds coming from a catalytic converter? Seems like that is where it’s coming from but I don’t know.

 

By chance do you notice it more when it's cold out? I have a very similar issue I'm having a hard time diagnosing, though I notice it the most when it is 60° F or cooler.

 

Which catalytic converters? the ones in the headers near the motor, or the secondary set in the ypipe? Seriously hope its just a cat that's bad and rattling and not something else. Any drivability issues or Check engine lights?

 

Secondary/rear . No engine lights. I’m trying to upload a video but it’s refusing to work

 

Sound is coming from the transmission. Most likely the flywheel. It's been documented around here about them cracking and causing a uneven 'tick'. One way to check is put a scope in there and look for cracks

 

Here’s a video https://youtu.be/Qbp3h-YE4Uw

 

what's the truck info

 

2011 v6 4door 4x4

 

Can't say for sure based on the vid...but it certainly varies with rpm, so it's definitely a rotating part that is making the noise.

 

Makes sense,, But, When you get under the truck, you hear it right at the Cat.. Like the engine pulses causing it.. I have seen some youtube videos of this.. But, like you said, its sounds like a rotating part issue.. But when I cant actually identify it as coming from the motor anywhere, it confuses me.

 

take it to a shop if you cant determine the source

 

just curious, is the sound is any different right after start up versus after everything is up to temp from driving around?

 

My '14/V6/MT6 does the same thing, has been doing it for the last 36k miles.

It got really loud last year during deer season, so when it got too hot to hunt mid-day, I took the DS cat cover off and found a small rock wedged between the cover and the cat.

That made it less noisy, but the noise is still there. From listening with a screwriver pressed to the cat, downpipe, bell housing, block, and a few other spots, it sounds loudest from the bell housing/lower block (just above the oil pan).

UOA's from Blackstone are fine, so I suspect it's something in the flywheel/TO/pilot/transmission area (bell housing probably acts to amplify the noise). Annoying AF, but doesn't seem to indicate an internal engine issue if the UOA's are a reliable metric for that.

Oh, yeah, and I plugged a fat forked horn later that evening, so double-bonus!

 

mines same way... many from this site have same sound...very "normal" and goes away after a few minutes of warming up.i thought it was piston slap but many from here have reassured me its normal.

 

google.... 2013 tacoma loud motor cold tacomaworld....

 

My 2015 sounds the same in the mornings during the cold starts. Once its warms up sounds dies down. There have been many posts on hear about the issues. Many have different appoints but majority I have read says "Normal". A few have even taken them in and all the mechanics say normal.

 

Check to make sure all of your heat shields are tight.

 

same issue here - think it might be caused by these support mounts on the passenger side: https://www.tacomaworld.com/threads/polyurethane-radiator-support-mounts-cab-also.361346/

 

doesn't change once warm.. hard to notice on cold startup because of the engine idling higher.. Not affected by weather. Tried the screwdriver to the ear thing several times.. I can never hear anything on the motor or bellhousing indicating its from there.. But, its also quite hard to rev the motor while im underneath it.. lol

 

You figure it out? Mine is similar.