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Omega Help Area => Omega General Help => Topic started by: Terbs on 28 January 2016, 13:43:30

Title: Strange noise
Post by: Terbs on 28 January 2016, 13:43:30
Hi all,
The 2.5 Elite has been stood for a month. Battery was a flat as a witches tit. However, attaching a starter pack gave a first time start.
But although the engine sounded sweet, there was a noise coming from the front...Bonk, bonk, bonk, very loud. After throttling, the noise disappeared, but came back at idle....bonk bonk......bonk.....bonk, bonk, bonk, but got softer, until after the engine has been idling now for an hour, with the odd revving up, you can barely hear it. I know its there....very very soft, and intermittent. Can a water pump bonk as well as squeal. Is the water pump on the 2.5 the one to the right of the auxiliary tensioner. TB told me once, but I have forgot !!! The noise seems to be somewhere in that area :y
Title: Re: Strange noise
Post by: Diamond Black Geezer on 28 January 2016, 13:51:02
Same issue myself, it appeared one day, and pretty noticeable. Not all the time, maybe only when cold. Before I was able to trace it the bleeding thing's disappeared again! Water pump's directly above the crank, sorry to not be of more help.
Title: Re: Strange noise
Post by: Terbs on 28 January 2016, 13:59:05
No probs, DBG. At least I am on the right pulley. However, its hard to locate exactly where the noise is. For one nasty moment I thought the cambelt was breaking up, but that is new, and I am sure the noise is not that. If the water pump was bonking, would that sound vibrate against the cambelt cover. :y
Title: Re: Strange noise
Post by: Diamond Black Geezer on 28 January 2016, 14:03:21
It's a thought. I had a 'psh psh psh' noise which I think MarkDTM recommended loosening and then drifting up the timing belt cover, as they cometimes catch. The noise seems to have gone away, too, as my car does tend to cure herself if you wait long enough  :D

Another method of diagnosing noises is to remove the Aux belt (for a short period of running only, of course) if the noise persist, then it's not coming from said belt/associated pulleys.
Title: Re: Strange noise
Post by: Terbs on 28 January 2016, 14:12:15
Did think that, about the belt. Is that just a case of levering the tensioner nut with a spanner, then slipping the belt off. Obviously make sure its clear of everything. Then just start the engine :)
Title: Re: Strange noise
Post by: Diamond Black Geezer on 28 January 2016, 14:15:08
Yes, simple as. I've got a 1/4mile long breaker bar which I use. Not a nancyboy thing, it's just you can control the amount of pressure on the tensioner so easily. It's not pretty when they slip off the socket and spring back! Loud noise = new underwear!

There'll be a diagram on here somewhere but to make life easy for yourself just make a quick note of the routing. I was mucking about 15 mins when I changed my belt before relenting and googled it!


Note: depending on your car, but at the time I had all the air con and intake junk out of the way when I changed my belt, so you may have more of a fiddle getting the belt out yours. But in essence, as above, release tensioner and pop belt off.  :)
Title: Re: Strange noise
Post by: Terbs on 28 January 2016, 15:33:05
Thanks DBG....TB did a belt for me a short while back on this car. He made it look easy... ;D Did take a few bits off though. I'll give it a crack tomorrow....got it charging now :y
Title: Re: Strange noise
Post by: STEMO on 28 January 2016, 16:14:10
At least your car is still capable of bonking, Terbs.  :)
Title: Re: Strange noise
Post by: Terbs on 28 January 2016, 16:37:21
At least your car is still capable of bonking, Terbs.  :)

That's more than I am, matey ;D ;D
Title: Re: Strange noise
Post by: 05omegav6 on 28 January 2016, 16:48:40
Might simply be lifter noise... Takes a while for the oil to get back up into them if stood for a while ;)
Title: Re: Strange noise
Post by: STEMO on 28 January 2016, 17:46:28
Might simply be lifter noise... Takes a while for the oil to get back up into them if stood for a while ;)
I don't think lifters 'bonk'. More of a 'tap'.  ;D
Or a 'clack'  ;D
Title: Re: Strange noise
Post by: Terbs on 28 January 2016, 17:49:02
Might simply be lifter noise... Takes a while for the oil to get back up into them if stood for a while ;)

I did think that possibly, Al....but they usually make a clacking noise, and this was not in the right place. I have had that happen with the lifters (I assumed) with the other car, but this noise was different. 'Bonk' is the only way I can describe it. I'll try tomorrow again....and if it is 'bonking', I'll try to record the sound. :y
Title: Re: Strange noise
Post by: 05omegav6 on 28 January 2016, 18:34:40
Might simply be lifter noise... Takes a while for the oil to get back up into them if stood for a while ;)

I did think that possibly, Al....but they usually make a clacking noise, and this was not in the right place. I have had that happen with the lifters (I assumed) with the other car, but this noise was different. 'Bonk' is the only way I can describe it. I'll try tomorrow again....and if it is 'bonking', I'll try to record the sound. :y
When I fired up the white one after six weeks, I thought the cambelt had jumped such was the racket :o
Title: Re: Strange noise
Post by: RolandL on 28 January 2016, 18:49:00
Hi terbert, just a thought. Have a good look at the aux belt tentioner pulley. Look for signs of the pulley breaking up,melting. A couple of years ago i had a pulley fail,the inner rubber wore, melted and there was a similar sound. I never realised what was going on until i started to loose electrics and power steering. When i had a good look, the pulley had created a larger hole so was not running as it shoud,hence the "bonk" . Suprisingly the pulley never parted company with its fixing.


Might be worth a look.
Title: Re: Strange noise
Post by: Terbs on 28 January 2016, 19:42:54
Thanks Roland....
I don't think its the tensioner, and I have had a new one...like yours, melted, and fell apart. Worth a closer look though :y
Title: Re: Strange noise
Post by: TheBoy on 29 January 2016, 18:10:09
Pop the aux belt off, and start car, checking for noise. If its no longer present, either belt, or one of the devices it turns. If still present, you need further investigation.

Obviously don't run it for more than 30s or so with no aux belt, as waterpump wont be running.
Title: Re: Strange noise
Post by: Terbs on 31 January 2016, 14:28:04
Did as suggested....ironically, I could not hear the noise in either circumstance :-\
For the moment, I'll have to put it down as one of life's ironies :-\
The engine sounds as quiet as a church mouse now. Sitting in the car, its hard to distinguish whether its actually running. So I don't think there is a major problem (at the moment) and I think lubrication was slow (be it water or oil) to reach its destination. :y
Title: Re: Strange noise
Post by: sjc on 31 January 2016, 14:44:16
Since it was stood for a while... could be a hump formed in the belt around the tensioner which took a little time and heat to straighten out since its so cold outside?
Title: Re: Strange noise
Post by: terry paget on 01 February 2016, 08:57:08
I always aim to run a spare car once a week. As baggers points out in the above 'battery drain' thread, after one week standing a car should start, after two it probably won't. Internal battery leaks, small consumption (clock, alarm, radio, etc.) drag it down. Leave it 6 months and all sorts of things go wrong; flat tyres, brakes sticking on, etc. A neglected car can get damp inside, grow mould, mice can nest in the air intake, etc.

If road legal I take the spare for a local journey of 4 miles or more, to get the oil and exhaust hot. If not road legal, I run the engine for 15 minutes and run it up and down the drive.

Apologies if you already do this, but you did day it had been standing for six months.