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

[AFei]

2004 LX470 @202700 miles.
Not sure if it's normal.
Any help is appreciated.




It looks like the voltmeter caused some confusion. The meter actually stopped working at most of time. The battery is fully charged overnight.

 

[JunkCrzr89]

No, unfortunately it’s not normal.

 

[hoser]

Your voltmeter on your instrument cluster shows trouble too.

 

[ROAM]

The voltage is certainly off but man oh man that sounds A LOT like the rod knock mine and about every other Discovery II w the 4.6 v8 gets after 100k. Ever overheated? The 4.6 would eat head gaskets, warp the heads and the cylinder sleeves would slip and bang against the liners. Sounded identical to your vids. Although if the voltage is the culprit, it could be the alternator pooping the bed and the ECU not having enough juice to fire the injectors properly. Have you driven it? Does it buck like it's running out of gas? Can you get under the truck and pinpoint where its coming from? Bottom end? Top end? Too "knocky" for an exhaust leak. Check the charging system first cuz your gauge says so...

 

[97 AZ LC]

Charge up the battery and try it.

 

[AFei]

Your voltmeter on your instrument cluster shows trouble too.

Charge up the battery and try it.

Actually, the battery is fine and just fully charged. The problem is the "famous" instrument cluster issue on LX/LC where most of those stepping motor stopped working.

 

[AFei]

The voltage is certainly off but man oh man that sounds A LOT like the rod knock mine and about every other Discovery II w the 4.6 v8 gets after 100k. Ever overheated? The 4.6 would eat head gaskets, warp the heads and the cylinder sleeves would slip and bang against the liners. Sounded identical to your vids. Although if the voltage is the culprit, it could be the alternator pooping the bed and the ECU not having enough juice to fire the injectors properly. Have you driven it? Does it buck like it's running out of gas? Can you get under the truck and pinpoint where its coming from? Bottom end? Top end? Too "knocky" for an exhaust leak. Check the charging system first cuz your gauge says so...

Sorry for the confusion of the voltmeter. The battery was freshly charged fully and new. It's just some meters no longer work.

Yes, I did drive it. However, couldn't hear it while driving and seemed normal driving as usual. However, it might be too much wind noise to hear this one.

I will test drive it more.

 

[saudi]

2004 LX470 @202700 miles.
Not sure if it's normal.
Any help is appreciated.




It looks like the voltmeter caused some confusion. The meter actually stopped working at most of time. The battery is fully charged overnight.

i have a similar sound on cold start up then dissapear after 40-50 seconds ive exellent oil pressure , im told toyota are aware of slight piston slap on some but not all engines ,but dissapears on hot engine i also wondered if it could be a lifter . However i cant say my sound and yours is the same just similar

 

[AlpineAccess]

Regardless, you're going to want to grab a engine stethoscope (or 16-24" piece of metal rod/tubing) and try to isolate this noise. The video makes it sound like it is in the bottom end of the motor but that can very easily be resonance transferring through metals. Motors in engine bays have a funny way of echoing and transferring sounds around.

As you've heard, its not normal. Has engine oil been changed regularly? Did this come on suddenly or has it been slowly increasing? Have you had any work done recently on the motor?

A loose spark plug can cause a loud tapping sound like severe piston slap. Check tightness on them, you'd know right away when you find the culprit.

 

[AlpineAccess]

i have a similar sound on cold start up then dissapear after 40-50 seconds ive exellent oil pressure , im told toyota are aware of slight piston slap on some but not all engines ,but dissapears on hot engine i also wondered if it could be a lifter . However i cant say my sound and yours is the same just similar

This could be piston slap but its unusual on a 4.7. What isn't unusual is exhaust manifold's/and exhaust manifold gaskets cracking. These iron manifolds do a tremendous amount of heat cycling in the 2 decades most of these have been on the road.

An adjustment in oil weight/type is a good way to check for piston slap. A heavier weight synthetic, or a change to standard on start-up will generally dampen/reduce piston slap noticeably. If you're running 0w20 or 5w30 you can go to a 10w30 or add an oil additive like Lucas prior to changing your oil to test. I don't like leaving stuff like Lucas in for the long term but a few hundred miles to verify if it changes the startup knock is ok.

Piston slap isn't great, but its not a sound of impending doom either - I've seen Subarus often run 200-300k after getting piston slap early in their lives (some as early as 60-70k). Our old subaru did 100k with piston slap (on an oem boosted motor) before going to the next owner. He got another 100k out of that motor before it was totaled in a collision.

 

[AFei]

Haven't driven it too much since I got it. So the oil change was about 3000 miles ago, and also the timing belt change. I believe it has such noise before the timing belt change. I could say the noise became more noticable but not significantly.

(or 16-24" piece of metal rod/tubing)

Will try to compare between cold/hot engine and see if I can find a way to isolate the area. Just hope the rig is blessed...

 

[JunkCrzr89]

So the oil change was about 3000 miles ago, and also the timing belt change. I believe it has such noise before the timing belt change. I could say the noise became more noticable but not significantly

Who did TB job?

 

[mitchjohnson000]

Rod bearing failure on 2UZ's is super rare. Unless it was ran dry on oil I don't think it's bottom end.

 

[LCtoLX]

I like what AlpineAccess wrote. If you don’t have a stethoscope, try using a long screwdriver or long metal anything. But be careful. You wouldn’t want to have it slip off of something and get caught up with a pulley or other moving part. In a past life I’d use this method to locate the culprit.

A couple of months ago, my son was going to drive off back to San Diego with our 96 LC that he’d been using while away at college. OMG, I heard a very similar noise to what’s in your video. I didn’t have the motivation to try and locate the problem but thought “Oh, no! Sounds like a blown lower rod bearing.” Called my friend from church (that still works as a mechanic) at home and luckily he was home. I didn’t want my son leaving on a 90 mile trip without knowing what the issue was. I followed my son to his home and he brought out his stethoscope.

It took 5 seconds to identify the problem. A loose spark plug.

Hopefully your issue can be identified easily by you or someone that you trust.

Cheers,
John

 

[AFei]

Who did TB job?

Kevin did this for me.

 

[AFei]

It took 5 seconds to identify the problem. A loose spark plug.

I just replaced the spark plugs yesterday and found out Jiffy Lube, where the previous owner had it replaced, used super cheap copper Autolite 3923 and charged the PO $10 each!

try using a long screwdriver or long metal anything. But be careful. You wouldn’t want to have it slip off of something and get caught up with a pulley or other moving part. In a past life I’d use this method to locate the culprit

I don't have experience on this type of technique. So basically, using the long metal stick to try to feel the vibration or?

Thanks!

 

[LCtoLX]

The engine stethoscope stand in or alternative, a long screwdriver, or 16-24" piece of metal rod/tubing as AlpineAccess wrote, is to hear what the noise “sounds” like. Forgive me for this poor analogy but it’s like a doctor trying to hear a heart murmur or wind rushing in your lungs. The stethoscope amplifies the sound and the stethoscope can be placed on different parts of the body.

Likewise, hearing the sound when you place the metal rod on different parts of the engine can give you a clue to what or where the sound is coming from. Not related to your issue but when a customer would complain about some bearing or metallic noice coming from under the hood, by placing the large, long screwdriver tip on the alternator, water pump, A/C compressor, etc., and your ear on the handle end, one can locate the offending bearing if it indeed was coming from one.

I hope that helps.

Cheers,
John

 

[AlpineAccess]

Ever put your ear to a railroad track and hear the rumbling of a train coming 10 miles away? Same theory we are trying to use here.

Metal transfers vibration very well when it's metal on metal. Gaskets, etc. deaden sounds so while it won't isolate a noise, you'll hear it clearly when you touch a metal rod to metal close to the source of the issue.

Cheapest version that I think works very well is a long extension, or a piece of metal conduit. Put it on a part of the motor and cup over the end. Bring your ear close to it just like a tuning fork it will transfer the sound.


With a tube, you can actually cup the end and putting it to your ear "aim" it at different parts of the engine bay. This gets rid of much of the air rushing noise from the fan.

 

[medtro]

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

 

[AFei]

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

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

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?