"Clunk" sound after turning engine off

Hello everyone,
I have a 2006 Tundra 4x4 with 269000 miles. Within the last 5-10k miles I have noticed a fairly significant "clunk" that seems to be coming from underneath the floorboard on the driver's side(Almost as if I can feel it under my feet). The sound resembles a light hammer strike to the frame. It only happens one time but on occasion it happens twice, never more. It only happens when the vehicle has been put into park and the engine has been shut off. It happens 99.9% of the time. Has anyone had a similar issue?

 

Are you parked on a grade when this happens?

Have you crawled under it and started pushing and pulling on things and given a visual inspection?

Any chance you can post some clear images of the undercarriage of where you believe this clunk is coming from from different angles?

 

Clunk when off vs clunk when the brake is relieved in P or N?

 

Does not seem to matter where or how I'm parked. I have been under a couple of times along with my uncle who is a fairly experienced mechanic. He has yet to hear the sound but did not notice anything when he went under. I will post pics. Thanks

 

If its driveline, it could be u joints or trans. If its engine, i’d guess it running rich and the extra fuel vapor could ‘pop’ one last time. I know its difficult describing a 3d problem through a 2d forum of pics and texts…

 

Checked your engine mounts?

 

No I have not.

 

I will look into this

 

I would also like to add that I do have aftermarket "fabtech" coil overs installed, if that helps any.

 

I just drove 1/4 mile, parked in my driveway, put in park, set brake, shut engine off and the noise happened roughly 2-3 minutes later then happeneda second time about 2 minutes after that.

 

Like cooling ‘tings’? Running hot?

 

Let's see pix if/when you can. Pix of the coil overs too. May help, may not. Sounds like your best bet is to crawl under it and wait after you shut it off.

 

Louder than cooling tings.

 

I'm beginning to suspect torque converter or something related since you can feel it in the floorboards and happens when you put it in P and shut er down.
Make sure bellhousing bolts are tight?

 

Similar thoughts BUT....

"I just drove 1/4 mile, parked in my driveway, put in park, set brake, shut engine off and the noise happened roughly 2-3 minutes later"

 

Trans cross member bolts?

 

In the mining realm we refer to this as a Tommyknocker.

 

I considered that too but that would be heard during acceleration and deceleration and over bumps. He states that it only happens when parked. Want to see pix.

 

Fuel pump pressure?

 

OP, I love a good mystery. How does the truck, ride, handle, steer and run? Anything unusual? Were the coil overs installed in the last 5-10k or did you make any other changes or have any other work done in that time-frame?

 

Axle wrap is a potential cause. Grease the slip joint on the driveshaft and see if it improves. My tacomas use to do this all the time when it was time to grease them

 

Yep i had that on my first Gen too

Checked and lubed everything

in the end I was low on trans fluid

i changed it and added 1/2-1qt extra just as a precaution

it stopped completely

 

Was this ever resolved. Be great to hear a solution. Thank you.

 

Clicked on his username and he hasn't been here since fall of 2023...

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Well shoot. I'm having the exact same situation as Jeffwaldo described. Loud hammer sound when engine is off. Happens for a few minutes. Way louder than "cool tings", but I have to imagine it has something to do with cooling because it will happen long after the truck has been off. Just started and nothing has been modified recently (one 400-mile-ish trip recently with some light offroading).

Sounds like I can do a trans drain and fill, and overfill a bit, but I'd rather not if that's not the confirmed solution.

Can anyone offer any other suggestions or confirm the trans fill?

Thank you.

 

Not the transmission. Topped off fluid. Did not fix.

Found similar post here: https://www.tundras.com/threads/loud-bang.141939/

Will look into cats and heat shield next.