LS400 whining noise.

Matt1986 · May 21, 2017

Hi all. I've had my LS400 for a couple of months now and it's always had a very slight whine from the engine bay, however it's recently become much more pronounced and now sounds like I have a supercharger under the bonnet.

I think it may be the alternator but want to be sure. Does anyone know a good lexus specialist in or near stoke on trent?

The whine follows revs and I don't think it's the ps pump. Anyone else had this. I'm not losing ps fluid. I changed it a while ago and the level seems the same to me.

All help and advice appreciated

Many thanks. Matt

NemesisUK · May 21, 2017

Have you checked the auxillary belt tension and it's tensioner?

Matt1986 · May 21, 2017

8 minutes ago, NemesisUK said:

Have you checked the auxillary belt tension and it's tensioner?

Hi. No I haven't done that, how would I test it. It doesn't look slack but it's clearly worn and needs changing. Could it be the belt?

NemesisUK · May 21, 2017

Possibly, could be a cheap solution, easily replaced

cornershop · May 21, 2017

I have a whine on my 98 car - it's the aircon compressor, easily tested.

The-Acre · May 21, 2017

You could just remove the serpentine belt and run it for a few seconds to see if the whine goes, that would eliminate the water pump as well. Have a new belt to put on afterwards. A very easy job. Sounds like a bearing anyway.

Matt1986 · May 22, 2017

8 hours ago, The-Acre said:

You could just remove the serpentine belt and run it for a few seconds to see if the whine goes, that would eliminate the water pump as well. Have a new belt to put on afterwards. A very easy job. Sounds like a bearing anyway.

Thanks, I'll give that a try. I'll get a new belt as well and see if that helps. Also should the fan run all the time?

Matt1986 · May 22, 2017

I took a video this morning. Perhaps this gives everyone a better idea of what I'm taking about. Sorry about the wind noise from the fan later in the video.

The-Acre · May 22, 2017

1 hour ago, Matt1986 said:

Thanks, I'll give that a try. I'll get a new belt as well and see if that helps. Also should the fan run all the time?

The fan doesn't run all the time when you're doing motorway type speeds as the air flow cools it, but it'll run a lot more when idling for some time as it's the only way for the coolant to keep low enough. I would certainly start by removing the belt, it'll take just a few minutes and then you can feel the idler etc for wear. It may even be as simple as the idler bearing, it's certainly that kind of whine.

Matt1986 · May 22, 2017

23 minutes ago, The-Acre said:

The fan doesn't run all the time when you're doing motorway type speeds as the air flow cools it, but it'll run a lot more when idling for some time as it's the only way for the coolant to keep low enough. I would certainly start by removing the belt, it'll take just a few minutes and then you can feel the idler etc for wear. It may even be as simple as the idler bearing, it's certainly that kind of whine.

I'll order a new belt and get that done this weekend. The fan runs even on a cold start which was what made me wonder. Thanks for the info. :-)

The-Acre · May 22, 2017

5 minutes ago, Matt1986 said:

I'll order a new belt and get that done this weekend. The fan runs even on a cold start which was what made me wonder. Thanks for the info. :-)

The fan shouldn't run on a cold start, that could be as simple as a sensor.

Matt1986 · May 23, 2017

Well today was the day. Alternator died on me. Managed to get home but now sat dead on the driveway.

I've ordered a new alternator which I'm collecting tomorrow and fitting myself. On removing the old one (eventually) it's covered in oil. I think it must be the pump above it so looks like a new pump as well!

Any advice on the pump?

The-Acre · May 24, 2017

7 hours ago, Matt1986 said:

Well today was the day. Alternator died on me. Managed to get home but now sat dead on the driveway.

I've ordered a new alternator which I'm collecting tomorrow and fitting myself. On removing the old one (eventually) it's covered in oil. I think it must be the pump above it so looks like a new pump as well!

Any advice on the pump?

This was often the problem with the early LS400, the power steering fluid leaking onto the alternator and damaging it. It was an easy repair but I'm not sure about the MK4

Matt1986 · June 10, 2017

So just to close this thread.

I Got hold of a new alternator from Europarts for £148 after the core refund and had my original pump rebuilt for £137 inc vat by Kelly bray steering, who were great and provided a great service.

All fitted on the drive with relative ease. Flushed ps system and gave her a full service and new auxiliary as well. Running perfectly and silently now.

After 2 weeks off the road I forgot how much I love driving it! Also after having the Battery disconnected for a while I've noticed the hesitation from a standing start is gone after it reset the ecu.

I'm a happy chappy 😀

Malc · June 10, 2017

Brilliant outcome

however i would check that darned ps fluid cooler pipe that runs the length in front of the radiator, they do tend to rust to bursting at about 20 years old ! can be replaced in copper tube for about a fiver.

Malc

The-Acre · June 10, 2017

1 hour ago, Matt1986 said:

So just to close this thread.

I Got hold of a new alternator from Europarts for £148 after the core refund and had my original pump rebuilt for £137 inc vat by Kelly bray steering, who were great and provided a great service.

All fitted on the drive with relative ease. Flushed ps system and gave her a full service and new auxiliary as well. Running perfectly and silently now.

After 2 weeks off the road I forgot how much I love driving it! Also after having the battery disconnected for a while I've noticed the hesitation from a standing start is gone after it reset the ecu.

I'm a happy chappy 😀

Excellent, well done. Just goes to show what you can save by avoiding the main dealer. Great price for the alternator as well!