Knocking When Warm

Ok. I have a knocking sound coming from my 99 Tacoma 2RZFE. Everyone I've been around has told me that they don't hear it. I've recorded videos of it and replayed them numerous times. Can't hear it in the videos. Period. Even 3 different mechanics, at a reputable shop, say they didn't hear it. Today, It's still present. Not sure what to do. Help.

 

Well, let's hope it's not rod knock (a bearing problem). They usually clack around 2k rpm most noticeably and spread from there. You can really damage the engine internals if this is what you are hearing.

Thankfully some mechanics say they don't hear it, so maybe there's some hope.

Take a old broom handle and cut it down to about 18" (can use a 3/8" long extension or something similar. Must be 1 piece and solid) Use this like a stethoscope and place it firmly on different parts of the engine. Put your ear to the other end and listen while a friend adjusts rpm from your signals. Try the block, head, valve cover, injectors. You will notice how the sound changes. Adjust rpm to try and find worst area and if condition is repeatable.

Tell us more, like milage, service, known accidents/issues, recent changes, how loud it is or location in engine bay.

 

Brief bit of history on the motor.
1- Pulled out of a 2000 Tacoma with 400k on the dash. Bought it from a junkyard for a decent price. By the time it was FINALLY dropped in, the 3 month warranty was up.
2- Soon after putting it in my truck the harmonic balancer decided to become quick disconnect, swapped that out.
3- Did an oil change but nothing else afterwards since it was running fine.

Also, I've put my big breaker bar against every surface I could think of before sending it to a shop.
Head, nothing.
Block, nothing.
Intake manifold, nothing.
Exhaust manifold, nothing.

I can hear it clearly and it sounds like it's at the front of the motor, near the top of the block.

 

Here are 2 videos of the truck idling.

https://youtube.com/shorts/mo13PrOfkvg?feature=share

https://youtube.com/shorts/IMyeR7-BSok?feature=share

 

That's good info. Obviously it's got a bit if miles, but no biggie.
First thing that comes to mind is valves. I'm a Vz guy, but with Rz I've heard the seats are soft and pound into the head over time. This eats up the valve lash and causes issues. I'm not saying it's your problem. Maybe pop the cover off and check the lash tolerance.

Compression or leak down test might shed light in this direction too.

 

You've got a lot going on in that area.

There's valves in a thin jap head, injectors, vsv and canister valves clicking on/off in rapid session.

I replaced my evap purge valve right there, and the new one is twice as loud as the original.

When I'm sitting idling in the driver seat....I can hear that evap valve over everything else.
Sounds like valve noise...but its not.

With a mid level scanner...I can watch all this going on....live data.

 

Several things. 1, I don't have the tools to check valve lash or the knowledge. 2, same goes for a compression test. I'm working with bare bone tools. Nothing special.

I understand that there's a lot going on in that area of the engine and I know what valve tap sounds like because my backup vehicle has a hell of a valve tap. This sounds like full on metal on metal contact,

Please understand that I'm not being mean or anything, I'm just explaining.

 

Yeah it could be a lot of things.....its gonna take some detective work.

any chance you have a stethoscope?

 

Nope.

 

Welp... Crap. That's all I got to say.

 

Bought a stethoscope and put against the block. It's knocking. No denying it now.

 

Okay. Update. Got the motor rebuilt just to start fresh.

 

and hows it runnin now?

 

Well overdue update on the engine. Here goes.
Way back around this time last year, got the engine rebuilt. EVERYTHING new outside of the crank, cams, head and block were new. Friend of a friend threw it together for x amount. Soon after it was done, I snagged it up and slammed it in the truck the next day. Basically alone.
Over the last year there have been a handful of small things that have popped on the truck. One of which was/is belt squeal like crazy when firing it up. The other is my exhaust literally falling apart. Front end saying 'nope' and breaking.
Overall? I trust the guy who rebuilt my engine and I'd recommend him to anyone. Plus my baby's still going strong.