Cambelt whine?

[ls400storm]

Dear friends

I have 1-2 minor issues with my LS400, (windshield, rear shock) and that will be sorted out in due course.

I am diverting my attention to the engine. There is a whine on the car associated with the revs, so when you rev up it increases.

I have checked the engine belt (new), all associated pullets, alternator etc and all these are in excellent smooth order.

This means that the noise is possibly cambelt related since I know what a tight cambelt sounds like and this is quite similar. 

Cambelt and waterpump was replaced at 67k by Lexus and again the cambelt and waterpump by a local garage at 91k. I acquired the car at 97k and I have receipts for this work. I belive that the cambelt is tight and therefore this noise.

My question is, did anyone experience something like this before? I know that the belt tensioner is hydraulic so there is no adjustment there. The 2 cambelt pulleys are also fixed without adjustment. Or am I getting this wrong? Are there actually any adjustments that can be made to either pulleys/tensioner unit to de-tension the belt?

Also, at this relatively low mileage of 97k I don't think that a cambelt tensioner/pulleys for this engine can go bad that easily.

Hope someone can shed light on this.

Thank you

 

 

[Tinonline]

There is no adjustment other than auto tension via the pulley via the tensioner unit. You are correct the cam wheels are fixed.

I would have thought a component or pulley bearing might be guilty and this is very close to the cambelt. Belt and water pump aside still leaves a few pulleys. After 70k miles mine had play but would have lasted quite a bit longer. But I replaced them any way including tensioner and tensioner pulley.

For piece of mind a view of the cambelt might be useful but will require some dismantling...but part of checking other components.

Any chance of recording the noise and posting?

[ls400storm]

Thanks, will post a video soon.

I am still left a bit dumbfounded as to how the belt could be tight and whining despite there being no adjustment.

I have a suspicion that the bolts that hold the automatic tensioner may been overtorqued when it was refitted when they changed the cambelt at 91k miles.

 

[steve2006]

  Could be the alternator loading up, have you tried removing the serpentine belt and running the engine without it to see if the noise has gone, you will obviously get the alternator charge light coming on during this.

[Tinonline]

On 14/10/2016 at 0:10 PM, ls400storm said:

Thanks, will post a video soon.

I am still left a bit dumbfounded as to how the belt could be tight and whining despite there being no adjustment.

I have a suspicion that the bolts that hold the automatic tensioner may been overtorqued when it was refitted when they changed the cambelt at 91k miles.

 

That would take load off, as the tensioner pulley could not move to apply full tensioner pressure...from the drop down tensioner. The long tensioner unit can't really be over torqued to such a state. 

But I think a thorough check on all areas needs to be done and all auxially belt areas. Can you get it back to your garage? I wouldn't expect to hear a cambelt making any sound at all.

[ls400storm]

Simon (and others) -

Here is a video recording I took with my phone in front of the radiator grill and the hood closed and idling at around 700rpm.  You will note the following-

1. A v8 american car type of burbling/gurgling sound. The frequency increases with the RPM. This is not normal and quite distinctive.

2. The whine that I am referring to. You will hear that this too increases with the RPM This is related to the burbling sound I believe.

Steve - The alternator is just 3 years old, the previous owner replaced it with a new unit, I can see that and also have a bill of around £400 for the work. I had recently changed the serpentine belt and idler pulley and also checked the tensioner pulley which was fine.

Thanks

 

[ambermarine]

Hi Mark

I had a problem with my Mark 1 similar to this ,the whine was very subtle and another symptom was blowing the coolant out of the expansion tank we thought it was a failed thermostat but it was a failing water pump which eventually seized and stripped the teeth off the cambelt, fortunately the Mark 1 had a non - interference engine so the valves were undamaged your' s has no such thing so you need to get to the bottom of this before the situation gets a lot worse .

Pumps can be faulty even if they are renewed the other point I would make is why would a oem pump need renewing after 20k miles .

[Tinonline]

Yep to me sounds like a bearing in a pulley or w/pump complaining. Recommend immediate and thorough investigation.