LS400 1996 65K weird noise

[SandorH]

https://youtu.be/zDw5gf5n5as
https://youtu.be/TlzeD4twnSs

Hi. My LS400 (1996 65K miles) sometimes feel like it is losing power and has a weird noise (sounds like an RC car) when it is speeding. I checked the engine controller which was in pristine condition, but to make sure everything is all right I changed the condensators to the recomended ones. It also had a major service yesterday to keep it in shape (oil system flushed, fuel system cleaned, oil changed, filter changed, front wheels balanced...), but this issue is still present. Is anyone had the same before?

[steve2006]

Welcome to the LOC.

I can’t see the problem from the videos.

[SandorH]

35 minutes ago, steve2006 said:

Welcome to the LOC.

I can’t see the problem from the videos.

Hi. Maybe the sound quality is not the best. Before this problem and when it's working properly like before, the car is way much smoother and has no scratchy bearing noise. You can hear it slightly on the video and it is way more louder on higher speed. I was looking around and it is possible to be the pulley or water pump, but I'm not a mechanic so want to make sure

[Malc]

at 24 years old it could be many things age related and not miles related

has the waterpump ever been changed ?  it's a big big job and owners might have shyed away from cambelt, pulleys and waterpump stuff coz of the low low miles

but 10 years is the time for it, at least a proper inspection or diagnosis however tricky that might be

Malc

[The-Acre]

As above, if it is the water pump it needs doing immediately as it could wreck the cambelt, then you're sunk!  You could remove the auxiliary belt (easy job) and briefly run the engine, if it stops being noisy you know it's not the water pump.

[Cotswold Pete]

I could hear the noise on one of the videos, and does seem to change with the revs.

Interesting that you said it is not as smooth as before, as my guess might be transmission issues, but not sure what you mean by smooth/scratchy

Do you get the same noise if you get to speed, then put the car in neutral and then rev the engine.  If noise is still there then I would be thinking water pump / cam belt problems.

 

[Mikaelse]

Yup.  I can hear the scratchy noise too on your video. Changes pitch with revs. My best guess is one or more of the sealed ballbearings inside the stuff on the motor front that has persihed. 
I have done cambelt and  auxiliary belt, water pump and idler bearings on two LS400 age 20 and 22 years . Some of the auxiliary belt bearings were stil working ok but made some "whirring" noise and grease inside more resembled black cheese then oil. If this is the case with your car the noise would have come gradually over some time.
20 Years is a descent life on those sealed bearings I think. If it is due ,  Do the full Cambelt, water pump, All idlers bearing change. My alternator bearings, freewheeling bearings in AC-compressor, and Fan bearings  I did not change . Those where smooth running, tight and seemed fine still.    

[Malc]

Sandor, did you get to the bottom of the issue ?

Malc

[SandorH]

On 4/5/2020 at 5:14 AM, Malc said:

Sandor, did you get to the bottom of the issue ?

Malc

Hi. The car had a full service and I got the ECU caps renewed, but it still had this issue "randomly". On some days it was working absolutely stunning on the others started like a crap and had no power. One day we broke our usual routine of hopping in the car, start it, turn the AC on and go where we need to be. At half way when we turned the AC on that weird sound started again... and this is where we realised how dumb we are. It was the AC compressor... So if you have a weird noise and power loss you can put this on your checklist