Noise from rear over 45 mph - thoughts please

[matt-me]

Hi. I have a loud hollow/brrrrr (?) noise from the rear after 45 mph. A difficult noise to explain but sounds like a cross between an exhaust blowing and a drone. It's not s whining or grinding noise. It gets louder as you go beyond 50mph and is constant. I have also lost power to pull above this speed, it gets there but needs cranking up. That could be the timing though which we are double checking.

I had my van serviced last week, oil change, valve clearances checked, timing done etc by s good guy and checked the timing again yesterday. The noise wasn't there before. Drove it camping over the weekend probably covered 160 miles, noise was there both down and back.

It is a 1914cc autoteknics engine 5 years old with a cogbox bearbox with taller fourth. This combo probably done no more than 8000 miles and all was fine before. It also has a year old vintage speed exhaust.

My thoughts to check at the weekend, when it is dry hopefully :

1. Wheel bearings, but these were checked when serviced by rotating and rocking, seemed fine then.
2. CV joints
3. Going to check the exhaust in case something loosened off, although no similar noise at low level.
4. Fan rub?
5. Alternator bearing? But i can't hear anything when reving it up not under load.

I can't think of much else and it has been so good so far. I am

One thing I am not sure of and need to check is if this noise is there only when under load (ie driving in gear) or if it disappears when clutch disengaged/not under load. We had a wheel bearing go on my sons clio and i think it might have been a similar noise but I imagine this would be there whether under load or not.

I can't think it is related to the service and hope it os one of those 'coincidences' but drawing a bit of a blank at this stage.

Any ideas please people?

Thanks Al

 

[Skiingnick]

If it's been parked up for a while, it could be that your tyres have flat spots on the rear. I had the same problem with my Alfa because it was park up on the drive for two years and made the sound you're describing.

 

[matt-me]

Thanks nick.

Jacked up the rear today and found the N/S wheel bearing is kaput, loads of movement. Must have been on its last legs and the full van and distance has taken it over the edge. Pleased to know what it is. Will change both sides...