Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: damon80 on 14 August 2009, 15:38:24
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Hi Folks,
I've noticed that at motorway speeds in my Miggy, when I lift off the accellerator, there's a grumbling noise. Put my foot back down to accellerate, and it disappears.
Any ideas??
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Given the year, there should be nothing worn. How many miles has she done?
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Done just over 100k
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Still would not expect problems. Have you jacked it up & spun the wheels? Could be a wheel bearing I suppose, Hope it's not gearbox.
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the noise from the front or back?
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Jacked the back up, no play in any rear wheel bearings.
Noise seems to be coming from the back end. I did suspect the diff, but I thought that if that was on the way out that it'd make a constant noise?
There's no noise whatsoever below 65mph...
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....
I did suspect the diff, but I thought that if that was on the way out that it'd make a constant noise?
There's no noise whatsoever below 65mph...
Have you grabbed hld of the rear of the prop shaft to see if there's any play? My Senator's input shaft nut had backed of so there was a little play in the bearing. I could get it to grumble a it accelerated or slowed down, but if you accelerated enough to just take the weight off the bearing the noise disappeared. Just nipping up the bearing sorted it. If this is your problem don't go mad as there should be a specific preload on the bearing, worked out with rolling torque gauges (inches/lbs) etc that none of us have access to.
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Cheers for the advice Andy - no, ain't tried that. Will give it a go.
How much play is too much? Because surely there should be a bit of play to allow for movement of suspension?
And correct me if I'm wrong - if it was a duffed diff, would the noise be constant, as oppose to the symptoms I'm getting?
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Cheers for the advice Andy - no, ain't tried that. Will give it a go.
How much play is too much? Because surely there should be a bit of play to allow for movement of suspension?
And correct me if I'm wrong - if it was a duffed diff, would the noise be constant, as oppose to the symptoms I'm getting?
You should just have a small amount of loading on the taper bearings on the input to the diff, and NO movement of the input shaft. It's unlikely that the diff will be shot so soon even if the input bearing is slightly slack. Have look at what moves on the suspension re the diff in put, the movement of the suspension doesn't have a bearing (no pun intended ;D) on the diff input shaft. :y
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This might seem a silly suggestion, but is the exhaust system sound at the back end?
Chased such a rumbling myself for a while until the blow got a bit less subtle. ::)
Kevin
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Cheers for the advice Andy - no, ain't tried that. Will give it a go.
How much play is too much? Because surely there should be a bit of play to allow for movement of suspension?
And correct me if I'm wrong - if it was a duffed diff, would the noise be constant, as oppose to the symptoms I'm getting?
You should just have a small amount of loading on the taper bearings on the input to the diff, and NO movement of the input shaft. It's unlikely that the diff will be shot so soon even if the input bearing is slightly slack. Have look at what moves on the suspension re the diff in put, the movement of the suspension doesn't have a bearing (no pun intended ;D) on the diff input shaft. :y
Jeez, what's that in English, Andy??!! Bearing in mind that I'm somewhat spanner-shy :-[
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This might seem a silly suggestion, but is the exhaust system sound at the back end?
Chased such a rumbling myself for a while until the blow got a bit less subtle. ::)
Kevin
Exhaust is getting ready for replacement tbh Kevin, but it's defo a mechanical sound as oppose to an exhaust blow.
Also, if I go over a bump on the motorway, when the load is taken off the suspension, the noise goes. Once the suspension settles, back comes the noise...
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As Kevin suggested it may be a loose baffle in one of the exhaust boxes, try giving each box a thump with a clenched fist :-/.
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you haven't recently put any wanli ditchfinders tyres on by any chance? ;D
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Cheers for the advice Andy - no, ain't tried that. Will give it a go.
How much play is too much? Because surely there should be a bit of play to allow for movement of suspension?
And correct me if I'm wrong - if it was a duffed diff, would the noise be constant, as oppose to the symptoms I'm getting?
You should just have a small amount of loading on the taper bearings on the input to the diff, and NO movement of the input shaft. It's unlikely that the diff will be shot so soon even if the input bearing is slightly slack. Have look at what moves on the suspension re the diff in put, the movement of the suspension doesn't have a bearing (no pun intended ;D) on the diff input shaft. :y
Jeez, what's that in English, Andy??!! Bearing in mind that I'm somewhat spanner-shy :-[
If you remove the 3 bolts at the diff end of the prop shaft and swing it to one side you can see the nut holding the diff input flange in place. On my Senator this nut was loose, it shouldn't have been, but don't tighten any ,ore than a nip, otherwise you'll bugger the input shaft bearings up. :y :y ;)
Any better Damon? ::) ;D ;D
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The traditional cause of this kind of noise is soft engine mounts and a badly fitted exhaust that makes metal to metal contact under certain conditions. The noise often sounds like some major mechanical component about to need expensive attention.
The diff is mounted in a subframe with rubber mountings. The subframe has to be lowered to change the road springs. Soggy mountings or loose bolts might allow the diff to move around & make odd noises.
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Cheers for the advice Andy - no, ain't tried that. Will give it a go.
How much play is too much? Because surely there should be a bit of play to allow for movement of suspension?
And correct me if I'm wrong - if it was a duffed diff, would the noise be constant, as oppose to the symptoms I'm getting?
You should just have a small amount of loading on the taper bearings on the input to the diff, and NO movement of the input shaft. It's unlikely that the diff will be shot so soon even if the input bearing is slightly slack. Have look at what moves on the suspension re the diff in put, the movement of the suspension doesn't have a bearing (no pun intended ;D) on the diff input shaft. :y
Jeez, what's that in English, Andy??!! Bearing in mind that I'm somewhat spanner-shy :-[
If you remove the 3 bolts at the diff end of the prop shaft and swing it to one side you can see the nut holding the diff input flange in place. On my Senator this nut was loose, it shouldn't have been, but don't tighten any ,ore than a nip, otherwise you'll bugger the input shaft bearings up. :y :y ;)
Any better Damon? ::) ;D ;D
Yep, much better thanks Andy! ;D
I'll have a gander int morning. Cheers bud
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The traditional cause of this kind of noise is soft engine mounts and a badly fitted exhaust that makes metal to metal contact under certain conditions. The noise often sounds like some major mechanical component about to need expensive attention.
The diff is mounted in a subframe with rubber mountings. The subframe has to be lowered to change the road springs. Soggy mountings or loose bolts might allow the diff to move around & make odd noises.
Hmmm, now that's a thought... I've noticed that if I "blip" the throttle when stationary, the car rocks from side to side - not a great deal, but much more noticable than in my last Omega.
Could this point to soft engine mounts maybe?
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1. I allowed my local garage to replace the pinion oil seal on my carlton (Omega A)(very similar diff with crush spacer between input shaft bearings). The diff was scrap after 30 miles because they did the nut up until it felt 'tight'. The input spider is on extremely tight splines, the nut is a self locking nut. If the nut has come loose you need to look for the reason why.
2. Try moving your tail pipe around with the engine ticking over, are all the rubber mounts in position and in good condition? has the exhaust system broken in two pieces? There are so many supports that a broken exhaust won't fall off but it will make strange noises. Does the exhaust make contact with parts of the suspension or body if you bounce it up and down?
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The traditional cause of this kind of noise is soft engine mounts and a badly fitted exhaust that makes metal to metal contact under certain conditions. The noise often sounds like some major mechanical component about to need expensive attention.
The diff is mounted in a subframe with rubber mountings. The subframe has to be lowered to change the road springs. Soggy mountings or loose bolts might allow the diff to move around & make odd noises.
Hmmm, now that's a thought... I've noticed that if I "blip" the throttle when stationary, the car rocks from side to side - not a great deal, but much more noticable than in my last Omega.
Could this point to soft engine mounts maybe?
Sorry, I wasn't trying to suggest that your engine had soft engine mounts, I was trying to draw attention to the ways in which rubber mounted items can make alarming noises if you get metal to metal contact.
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..... the nut is a self locking nut. If the nut has come loose you need to look for the reason why. ......
It's a long time ago now, but I'm sure that my Senator's wasn't a lock nut. :-/ Possibly it should have been, it would make sence to me if it had been. I used a squirt of Locktite on my nut! ::) :y :y
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what about propshaft whirl? the centre bearing on the shaft, dont know if this is a problem or even present on these, then but my carlton had one go at about 120000 miles