Need help to determine the source & cause of the knocking noise

[medtro]

Thank @AlpineAccess and @LCtoLX , and I will give it a try and learn.


The LX sit in garage at most of time, and it was about 2 month recently. If this is the case, I'd expect the noise gone progressively if I drive more often?

Damage has been done if it is rod bearing knock. You will need new rod bearing(s) to have the noise gone. I would drain the engine oil to see if there is any debris from rod bearing.

 

[JunkCrzr89]

How long the engine sat and not started until you started it recently? I am guessing rod bearing knock due to "lack" of oil.

For one that sits for extended periods (months), do you suggest pulling plugs and adding a tablespoon of oil in each to lube the pistons before start-up? We used to do this on my dad’s 40 with the F engine, after it sat all winter.

 

[medtro]

For one that sits for extended periods (months), do you suggest pulling plugs and adding a tablespoon of oil in each to lube the pistons before start-up? We used to do this on my dad’s 40 with the F engine, after it sat all winter.

Probably a good idea and won't hurt. What I have been doing is pull the EFI fuse and crank the engine without starting it. Sometimes I cheat on newer model with cranking hold function, I shut off the ignition right before the engine is started, do this a few times prior to the real start.

 

[JunkCrzr89]

Probably a good idea and won't hurt. What I have been doing is pull the EFI fuse and crank the engine without starting it. Sometimes I cheat on newer model with cranking hold function, I shut off the ignition right before the engine is started, do this a few times prior to the real start.

Just to get things moving without the demands and friction of full combustion?

 

[medtro]

Just to get things moving without the demands and friction of full combustion?

Just to make myself feel good

 

[dace voit]

DAmn. Sounds like a knocking rod. I hope not! Another way you can isolate the sound is by disconnecting either injectors or coils one at a time while the engine is idling. Unplug one, if no change in sound, then plug it back in and move down the line until you've checked all 8. It will run rough when you unplug whichever you choose but once you get to the bad cylinder(if there is one) the knock will typically quiet down or go away. From you videos, it sounded like the knock was a little louder on the left side(DS).

Good luck. I hope it's not bad!

 

[saudi]

would knock dissapear after a minute

 

[AFei]

DAmn. Sounds like a knocking rod. I hope not! Another way you can isolate the sound is by disconnecting either injectors or coils one at a time while the engine is idling. Unplug one, if no change in sound, then plug it back in and move down the line until you've checked all 8. It will run rough when you unplug whichever you choose but once you get to the bad cylinder(if there is one) the knock will typically quiet down or go away. From you videos, it sounded like the knock was a little louder on the left side(DS).

Sounds like something do-able.
To clarify:

• this test is to be done while the engine is running and idling.
• coil or injector, which one is easier to work on? Never worked on injector before...
• Do we just un-plug the coil or injector with the electronic connector connected? or maybe just un-plug the electronic connector?

Thanks!

 

[AFei]

would knock dissapear after a minute

It didn't disappear unfortunately...

 

[AFei]

DAmn. Sounds like a knocking rod. I hope not! Another way you can isolate the sound is by disconnecting either injectors or coils one at a time while the engine is idling. Unplug one, if no change in sound, then plug it back in and move down the line until you've checked all 8. It will run rough when you unplug whichever you choose but once you get to the bad cylinder(if there is one) the knock will typically quiet down or go away. From you videos, it sounded like the knock was a little louder on the left side(DS).

Good luck. I hope it's not bad!

Also just realized that the air box has to be removed to access coil for cylinder 4/6/8 (Passenger Side). So, it can't be done for them but all others, right?

 

[ROAM]

Easy way to tell if it's top or bottom end is...the top end will turn twice the rate of the bottom/crank. So as you slowly idle up the knock will increase evenly with rpms. The top end, for example a lifter will double the speed of the crank so the noise's "speed" will increase 2x. Lifters are more of a tic sound. Yours sure sounds like a knock. However as previously mentioned, these motors rarely suffer from that. Two months of sitting would affect the top end more since the crank would have the luxury of being closer to the pan. A bad oil pump or clogged sump would be indicated on the gauge.
Ideally you could take the pan off and check the bearings by hand. Any play and the associated rod would knock.
A bad injector or coil pack would throw a code.

 

[AlpineAccess]

Just keep in mind that the odds of this being rod knock is VERY low, and your focus should be on pin pointing the knock first before starting to test things randomly. You can introduce a problem into the system.

You can literally just set a stethoscope or rod on an injector and hear it tapping away rythmically, like a sewing machine ticking along without the stethoscope and like a single ballbearing rythmically hitting a chunk of metal with the stethoscope (rod tool). You will hear if one is stuck for example.

You will really want to pinpoint this issue and provide everyone here with more information or opinions are going to vary greatly, as you can tell so far

 

[AFei]

Just keep in mind that the odds of this being rod knock is VERY low, and your focus should be on pin pointing the knock first before starting to test things randomly. You can introduce a problem into the system.

You can literally just set a stethoscope or rod on an injector and hear it tapping away rythmically, like a sewing machine ticking along without the stethoscope and like a single ballbearing rythmically hitting a chunk of metal with the stethoscope (rod tool). You will hear if one is stuck for example.

You will really want to pinpoint this issue and provide everyone here with more information or opinions are going to vary greatly, as you can tell so far

Thanks for the advice. yes, I will try to find a rod to listen it first. Will report back.

So for the areas to listen on, you just mentioned injector. Any other area I should try?

 

[2001LC]

Sounds like a Tundra. Check engine VIN #.

Additionally monitor engine temp , oil pressure, and change oil & filter.

 

[AlpineAccess]

Thanks for the advice. yes, I will try to find a rod to listen it first. Will report back.

So for the areas to listen on, you just mentioned injector. Any other area I should try?

I wouldn't tell you to start looking at certain areas as it will throw off your results. Just start putting the diy stethoscope on different areas of the motor and see where the noise you're hearing is coming from.

This isnt a noise made by an injector, FYI. I was simply giving you an example of the differences in sound from no steth to a steth. Also to say you don't need to remove/replace parts to narrow this down.

 

[AFei]

Sounds like a Tundra. Check engine VIN #.

Additionally monitor engine temp , oil pressure, and change oil & filter.

No, it's a 2004 LX470, not Tundra, although they share same engine I believe.

I got this LX in 2018 at 199K miles, and put 3.5K miles since. Was planning to build a overlander but job relocated to NE so didn't spend enough time with it. I have replaced oil/filter, ATF, Tx Case Fluid, F&R Diff Fluid, and AHC Fluid. Also the timing belt got replaced earlier 2019.

During the past 2000 miles, the engine surfed with random misfire code, and some time it ran roughly during cold start. However, replaced a new battery in Feb, and it seemed having cured the misfire issue. This week I replaced the spark plugs and inspected all coil packs were in good shape. Found the old plugs were cheap copper one, one coil pack was very loose, and some plugs were very tight.

I don't think the misfire may relate to the noise but give full background of this rig.

Will do a oil change over the weekend and also try the diy stethoscope to see if anything can be found.

 

[JunkCrzr89]

No, it's a 2004 LX470, not Tundra, although they share same engine I believe.

He’s implying that an engine from a Tundra was swapped in before you purchased the LX. Check VIN on engine and compare with VIN on your door jamb.

 

[dace voit]

Sounds like something do-able.
To clarify:

• this test is to be done while the engine is running and idling.
• coil or injector, which one is easier to work on? Never worked on injector before...
• Do we just un-plug the coil or injector with the electronic connector connected? or maybe just un-plug the electronic connector?

Thanks!

Yes. Just unplug the connector. Which one doesn't matter.

Also just realized that the air box has to be removed to access coil for cylinder 4/6/8 (Passenger Side). So, it can't be done for them but all others, right?

If you can access a plug, then you're good. As far as 4/6/8, I don't know if you can unbolt the airbox from the VC and rotate up enough out of the way or not. If you can't access those cylinders then you'll have to figure something out there.

Full disclosure: I have not done this test on a 2UZ. I don't mean to mislead and sorry if I have. I've done it on other motors with success. A mechanics stethoscope is good advice and are cheap to buy at most any FLAPS.

 

[AlpineAccess]

No, it's a 2004 LX470, not Tundra, although they share same engine I believe.

I got this LX in 2018 at 199K miles, and put 3.5K miles since. Was planning to build a overlander but job relocated to NE so didn't spend enough time with it. I have replaced oil/filter, ATF, Tx Case Fluid, F&R Diff Fluid, and AHC Fluid. Also the timing belt got replaced earlier 2019.

During the past 2000 miles, the engine surfed with random misfire code, and some time it ran roughly during cold start. However, replaced a new battery in Feb, and it seemed having cured the misfire issue. This week I replaced the spark plugs and inspected all coil packs were in good shape. Found the old plugs were cheap copper one, one coil pack was very loose, and some plugs were very tight.

I don't think the misfire may relate to the noise but give full background of this rig.

Will do a oil change over the weekend and also try the diy stethoscope to see if anything can be found.

Was it making this noise before you did this work on it recently?

 

[AFei]

Yes. Just unplug the connector. Which one doesn't matter.

Thanks! Will try something over the weekend...

Full disclosure: I have not done this test on a 2UZ. I don't mean to mislead and sorry if I have. I've done it on other motors with success. A mechanics stethoscope is good advice and are cheap to buy at most any FLAPS.

Fully understandable. Proceed at own risk... Thanks for the advice.

Was it making this noise before you did this work on it recently?

It has the noise before. I thought it must be related to valve adjustment as it sounds like the valve noise on my DD (Acura). However, after some research, realized it may not be same.