I went out in my wife's friends vrs last night as she wanted my opinion on a problem she's got.

it's a weird one, at approx 2500 rpm in 6th on the motorway (80mph on speedo)there's a weird pulsing through the cabin which you can hear more than feel.

There's also a pulsing at idle, but only on the odd occasion, not all the time.

drop the speed down to about 75 (or above around 85 on a private road!) and the pulsing goes away...

anyone got any ideas?

2500 is more or less the start of full boost isn't it?

Could that be a link to the problem?

That's when the torque suddenly shoots up?

Maybe engine or dogbone mounts.

Somethings struggling with the full delivery of torque

I reckon.

Could be tyre noise but unlikely? Wheel bearing?

Perhaps dmf starting to fail? Mine made noises

at specific rpms and more noticeable in certain gears

just before I had it and the clutch changed.

If you dip the clutch at 80 does the noise disappear? If not need to look at non-engine. Tyres, shocks, suspension. Also check for non-mechanical parts such as flaps, undertray etc. At same rev range in another gear any noise? It may take a while to solve as it is a case of eliminating everything. The idling pulsation may (or may not;-)) be a red herring. Worth checking silly things such as windows are tight and have people in the back as well as in the drivers seats.

As above. Try going to 5th and doing the same speed and also dropping clutch.

Sounds like it could be wheel bearing but only if the noise continues with the clucth down and engine idling. I had one in the peugeot that went. Sounded like a washing machine sat in the back that disappeared over 80mph.

The pulsing at idle could be something and nothing. Ours does this where the engine will suddenly start very slightly shaking the car but I have noticed that it seems to be related to the A/C fan and compressor kicking in (climate control) and as the electrical load changes.

Are there any weird noises at idle in when you press and release the clutch?

Might be worth getting a fault code scan just to rule anything out.

I'm guessing it's a later vRS (54 plate or newer) with the BLT judging by the revs at 80mph.

Phil

I would be looking at wheel bearings and clutch. As above drop the clutch and see if noise goes away if it does I would say clutch but if it doesnt then its something other than mechanical such as bearings etc.

I'll try and get out in it again over the weekend re dipping the clutch at speed.

I don't think it is the flywheel though, because the noise isn't there at 2.5k revs in 3rd, or 4th. There was possibly some noise in 5th at the same revs but it was hard to tell.

In 6th though it's very audible, you can sort of feel it a bit in like an 'air-pressure' kind of way, very hard to describe, but you can sort of feel it in the cabin as well as hear it??

I've been out in this womans car again and it seems speed not rev's related.

the noise isn't there at 2.5k revs in any other gear and doesn't seem to go away when you dip the clutch - although this is hard to judge as the car drops speed quickly with no drive at that speed (not the most aerodynamic the fabia is it!)

It seems to be driving normally, boosts nicely etc, not sure what to look at first. The other thing is it doesn't seem 'directional', it just seems to 'fill the cabin', so it's very hard to tell where it's coming from ??

So just 6th gear at 2.5k? I would say its the cltuch/flywheel starting to show signs of wear mate. 6th gear and 2.5 is fairly torque happy shall we say and if anywhere thats where the clutch/flywheel will start to feel the pain and as the speed picks up the strain will go away slightly.

But the noise doesn't go away if you dip the clutch, the revs drop but the pulsing remains until the car drops to about 75mph ?

Oh sorry missed that bit, not clutch/flywheel then. really need start looking at bearings and such in that case.

OK, so jack up each wheel one at a time and push/pull the wheels to feel for movement in the wrong direction?

Jack up each corner and spin the wheel to check for bearing play dude.

please forgive my ignorance, but I thought pulling the wheel forward and pushing it backwards (i.e. one hand on the top of the tyre and one on the bottom)was the way to check if there was play in the bearing?

what am I looking/listening for if spinning the wheel?

ta very much!

Looking for a grinding noise when spinning, hand and top and bottom and left and right checks various bushes.

It sounds as if it is a speed related issue rather than a drive related issue. Has she had new tyres fitted lately? The increase in forces present when you jump from 70 to 80mph is pretty massive so it could simply be that a wheel is now out of balance (especially if they are cheaper tyres) or has a wheel lost a balancing weight? Worth checking the obvious before you get carried away.

If this isnt the case and you're looking at bearings etc, wobble the wheels (all 4, even if you find the first one to be obviously shot) each and every way, don't just do it top and bottom as it can sometimes depend on how everything has come to rest. When running the wheel round, you should probably notice a grinding noise as others suggest or resistance that may either be continuous (compared to other wheel) or resistance that gives a notchy feel as if there is bits of grit or something inside the race. Cant describe it too well at this time of day but reckon you'll know it if you feel it. Also, its worth doing it before and after a drive - metal expands when hot so it may be a problem that appears after a 10min run up the motorway and back...

If it is serious, you may also notice signs of discolouration on the metal surfaces.