Hi All, I've got this really annoying noise that I can't pin down.
It's a high ringing sort of noise, like it is making the guard around the exhaust manifold vibrate or something similar, but I just can't quite work it out. There are a few specifics:
- Only there between 1000-1250 rpm
- Seems to only be there after the vehicle comes up to temp
- Have heard recently a couple of times as it was being started, but then not again until warm
- With aircon on it sits idling at about 1000 rpm and catches the noise, for example at the lights
It is a 4800 Petrol, GU, 2001.
Seems there is something causing it to "resonate" just at those revs. So the noise might not even be coming from the source of the problem (e.g. a bearing might be a bit knackered and that vibration is causing something like the guard around the exhaust manifold to vibrate).
Had a few friends and also mechanics look at it. Hard to even tell exactly which area the noise is coming from. One guy was trying to convince me it was a stone rattling in guard around the exhaust, but it's not that.
Had a thorough look with another mechanic. He had a nice commercial "stethoscope" with a long rod on it. Stuffing around touching everything you could find I was convinced with him that there was a bearing type noise coming from the power steering pump. He had it out and sent to someone - they "cleaned it", but reckoned there was nothing wrong with it. We thought it was still coming from there and that they were hopeless. Off to the wreckers and got another one (a whole other cross-cultural experience that is here - I don't belong down there and can't avoid the "white man" tax!!). We put it in and the noise exactly the same. So, there was nothing wrong with the power steering pump!!
So, in the end all the belts came off (including to water pump). So no belts on at all and noise is still there, so that rules out alternator, aircon compressor, etc.
We had a long discussion and he took it to some other contacts to discuss things like timing chain. Everyone reckoned timing chain related issues should be there throughout the rev range (maybe to different noise levels, but at least detectable). In the end he gave up and went back to being a Land Rover mechanic. LOL
Above and below those rev ranges the engine is smooth. At normal idle it is smooth. The car is still driving and running fine. The noise is getting louder though - I think in my head!!! It's really starting to do my head in that we can't easily work out what it is.
Maybe it's just something loose somewhere and nothing more.
Any ideas anyone? Anyone come across something similar?
I've tried to record it, but it's hard to get a good recording with all the background noise. I tried to tweak it a bit to lower the background frequencies. In the recording it's idling without noise. Then I put the aircon back on and rev it slightly to the get the idle to sit back at 1000 rpm. About half way through the recording you can hear the noise come in.
Hopefully someone is going to steer me in the right direction.
Thanks,
Cameron.