Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: ians on 06 November 2007, 11:43:50

Title: Clonking from rear
Post by: ians on 06 November 2007, 11:43:50
When going round a right hand bend (only) - eg roundabout -  I have started to get a distinct knock-knock-knocking noise from the rear end.  Pretty sure its coming from the near side so presumably when something is loaded due to the cornering.

I've had a superficial look in less than ideal conditions and can't see anything amiss - broken spring etc.
Tried rocking/bouncing the car and the rear wheel although not had a chance to jack it up yet - again nothing obvious.

Suggestions?

Cheers,
Ian
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 06 November 2007, 11:59:22
Is it the rear or does it sound like the back of the tunnel (just behind the seats).
Title: Re: Clonking from rear
Post by: ians on 06 November 2007, 12:03:49
Hmm difficult to say offhand but I'm pretty sure its coming from the nearside.
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 06 November 2007, 12:05:44
Do a simple test for me......open the boot and press the boot floor having pulled the carpet back about 6 inches in from the rear panel and 4 inches across from the spare wheel.
Title: Re: Clonking from rear
Post by: ians on 06 November 2007, 12:12:30
OK - will do when I go out at lunchtime.

But this is an estate - make any difference?

What am I looking for?
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 06 November 2007, 12:13:44
Same applies.....its related to exhaust mount/heatshield.
Title: Re: Clonking from rear
Post by: bob.dent on 06 November 2007, 14:00:08
This is interesting, I'm getting a similar thing with mine but it only happens when going round left hand corners. :-?
Title: Re: Clonking from rear
Post by: ians on 06 November 2007, 14:13:27
Mark - I tried 'pressing' the boot floor but didn't notice anything.   The exhaust mount feels about the same as normal - certainly needs a fair bit of force to get it to contact the body,  although the noise does sound like that - a bit too regular I would have thought though.


Bob - if all else fails we can make a combo - then it will do it in both directions ;)
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 06 November 2007, 14:32:54
Quote
Mark - I tried 'pressing' the boot floor but didn't notice anything.   The exhaust mount feels about the same as normal - certainly needs a fair bit of force to get it to contact the body,  although the noise does sound like that - a bit too regular I would have thought though.


Bob - if all else fails we can make a combo - then it will do it in both directions ;)


Ok, as a final check, look under the back near the rear can at the heat shield above the exhaust back box....give it a wiggle....
Title: Re: Clonking from rear
Post by: ians on 06 November 2007, 14:36:14
I did have a bit of a poke in there when I was waggling the exhaust and nothing obvious.

Title: Re: Clonking from rear
Post by: bob.dent on 06 November 2007, 14:38:44
Quote
Mark - I tried 'pressing' the boot floor but didn't notice anything.   The exhaust mount feels about the same as normal - certainly needs a fair bit of force to get it to contact the body,  although the noise does sound like that - a bit too regular I would have thought though.


Bob - if all else fails we can make a combo - then it will do it in both directions ;)

 ;D ;D ;D

Mark - tried the test but nothing apparent. I did mention it to my garage when it was in for service a couple of weeks ago and they thoroughly checked under the car a couldn't find anything obvious as to the cause.
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 06 November 2007, 14:41:31
Quote
I did have a bit of a poke in there when I was waggling the exhaust and nothing obvious.



Ok, next quick test which is a little harder to do is to reach under the car and grab the prop shaft near the centre bearing and give it a wiggle......repeat on the front and rear prop section.
Title: Re: Clonking from rear
Post by: bob.dent on 06 November 2007, 14:46:25
Quote
Quote
Mark - I tried 'pressing' the boot floor but didn't notice anything.   The exhaust mount feels about the same as normal - certainly needs a fair bit of force to get it to contact the body,  although the noise does sound like that - a bit too regular I would have thought though.


Bob - if all else fails we can make a combo - then it will do it in both directions ;)


Ok, as a final check, look under the back near the rear can at the heat shield above the exhaust back box....give it a wiggle....

Just tried that, but nothing - no movement at all. Looks like it's going to be one of life's little mysteries. :-/
Title: Re: Clonking from rear
Post by: raximax on 06 November 2007, 14:52:01
check your jack and cd compartment for loose items you never know :-/ :-/ :-/
Title: Re: Clonking from rear
Post by: bob.dent on 06 November 2007, 15:00:01
Quote
check your jack and cd compartment for loose items you never know :-/ :-/ :-/

Hmmmm.....this did cross my mind. I've got a few bits in the spare wheel compartment that I'm gonna try moving to see if it makes any difference.
Title: Re: Clonking from rear
Post by: gofwb on 07 November 2007, 08:54:14
I have had this twice knocking from one side at rear when going around slow corners.

Turned out to be a broken rear spring, a section of coil can break off at the bottom, at first glance you wont notice it, but if you look closely you can tell its broken.


Title: Re: Clonking from rear
Post by: Kaycee on 07 November 2007, 09:08:24
i had exactly same symptoms also broken spring its the tail wat goes into captive thingy hard to spot if you dont look closely
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 07 November 2007, 09:26:31
It is broken springs symptoms........but the user said hes checke that.

Perhaps its time for a closer check.
Title: Re: Clonking from rear
Post by: ians on 07 November 2007, 10:51:07
Mark et al,

I did consider a broken spring - I know how the broken bit can lie unseen in the collar at the bottom.  I had a feel around and nothing obvious.  I'll take the wheel off at the weekend and have a closer look.

I did notice that the diff is seeping oil - I think from the prop shaft connection.   I'll top it up of course, but is there any chance this is the problem?

Cheers
Ian
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 07 November 2007, 11:02:43
Quote
Mark et al,

I did consider a broken spring - I know how the broken bit can lie unseen in the collar at the bottom.  I had a feel around and nothing obvious.  I'll take the wheel off at the weekend and have a closer look.

I did notice that the diff is seeping oil - I think from the prop shaft connection.   I'll top it up of course, but is there any chance this is the problem?

Cheers
Ian

Unlikely to be the diff pinion oil seal causing it.

What you wil find is that when you remove the level plug, oil will come out......unlikely to need topping up at all.
Title: Re: Clonking from rear
Post by: ians on 07 November 2007, 11:07:44
I thought the level was supposed to be (9mm?) below the plug?
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 07 November 2007, 11:58:11
Quote
I thought the level was supposed to be (9mm?) below the plug?

No, thats the manual gearbox (8mm I think), the diff oil should be level with the plug but, as the oil ages the long chain molecules get chopped up which gives an increase in volume and hence why it runs out when you check it.
Title: Re: Clonking from rear
Post by: ians on 07 November 2007, 12:05:49
Quote
Quote
I thought the level was supposed to be (9mm?) below the plug?

No, thats the manual gearbox (8mm I think), the diff oil should be level with the plug but, as the oil ages the long chain molecules get chopped up which gives an increase in volume and hence why it runs out when you check it.

Ah - when I first got the car I did check the gearbox (manual) oil and it ran out when I loosened the plug - that would explain it.

Is the pinion oil seal a big job to replace?   I'm suspicious of Mr Haynes and his comments about setting up the pre setting on the pinion.
Title: Re: Clonking from rear
Post by: Marks DTM Calib on 07 November 2007, 12:09:26
Its not to hard as long as you are careful, I have two to do fairly soon (including one on AA's car but, I need to get my white gloves laundered first) at which point I will add some pics to the maintenance guide (which is currently all text)
Title: Re: Clonking from rear
Post by: TheBoy on 07 November 2007, 19:57:37
Vaguely remember something in TIS about a rear clonking - something to do with panelling under rear seat iirc...
Title: Re: Clonking from rear
Post by: lee4206 on 07 November 2007, 20:57:38
I had a similar problem on mine turned out to be the rear anti-roll bar bushes worn and gone hard.
Worth a check
Title: Re: Clonking from rear
Post by: Glenn on 08 November 2007, 20:30:20
Could be rear subframe bushes.........