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Metallic Tapping Sound Only Under Load?!


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#1 Archived4

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Posted 24 October 2014 - 05:34 PM

Hi all,

 

My 1989 metro with original big valve head(refurbed if that makes a difference) taps like len goodman under load.

 

It sounds like a metallic tapping, but it isnt the tappets as it doesn't tap when idleing at 1000rpm.

 

It increases as the engine speed increases and has got louder recently.

 

Tappet clearences adjusted to factory settings

 

Any ideas what it is? I think it is without a doubt engine, but what?

 

It almost sounds electronic too, so could it be distributor? Or potentially alternator?



#2 carbon

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Posted 24 October 2014 - 05:43 PM

If this noise is when under load it may well be pinking/pre-ignition.

 

If you're not already using 99 octane fuel run the tank right down then put in half a tank of 99 octane. If the noise goes away then you have three main options :

- continue using 99 octane

- retard the ignition timing

- take head off and decoke / increase chamber size

 

Take it easy in the meantime, pinking/pre-ignition is very hard on the engine internals.



#3 Archived4

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Posted 24 October 2014 - 05:44 PM

Oh bugger! Will run the tank down tomorrow and stick some 99 octance in! Cheers!



#4 Archived4

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Posted 24 October 2014 - 05:46 PM

infact the plugs were very sooty, is that a symptom?



#5 carbon

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Posted 24 October 2014 - 05:48 PM

No, sooty plugs would suggest your mixture is set on the rich side



#6 Archived4

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Posted 24 October 2014 - 05:57 PM

Ah right. Just making sure. I knew it was running rich anyway and Ive now got the mixture weakened a lot since then. But will try higher octance fuel as I know the compresion ratio is quite high so if it might be pinking I'll see if this cures it. Cheers for your help



#7 Archived4

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Posted 25 October 2014 - 11:17 PM

Well isn't solved. I was driving it today, and it still persists even when using momentum 98 octane stuff. But one thing that did happen is the car started to stutter, and misfire once or twice, and the rev counter was bouncing around like no mans business. Yet I was doing a constant speed. Could this be coil issues or distributor issues?



#8 69k1100

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Posted 26 October 2014 - 02:58 AM

Check the rotor button for cracks.

#9 Dan

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Posted 26 October 2014 - 06:10 AM

When you say you leaned it off a lot did you do that with the help of any tuning aids such as a Colortune or did you just guess? If it's over lean it will be running hot inside the chambers and that is another cause of pre-ignition. Does it run on?

#10 albo

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Posted 26 October 2014 - 10:15 AM

metallic tapping under load, hope its not your big ends or even one



#11 Dusky

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Posted 26 October 2014 - 11:07 AM

Could me headgasket /airleak at the exhaust manifold gasket.

#12 Archived4

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Posted 26 October 2014 - 12:18 PM

The car's had a fresh engine rebuild, new big ends and mains, new oil pump etc etc, so it isn't them. Will have to double check the exhaust manifold gasket but shouldn't it do that at idle if it were that? Plus if the rev counter was bouncing all over the place then isn't it a coil issue? And we leaned it off after a trip to the mot station as it smelt a bit rich and wouldn't idle under 1200rpm but now idles perfectly, it's only when driving along and revs increase that the tapping does. Will try and get a video but I'm almost certain something is wrong. It isn't timing chain cover either as when we fitted a duplex chain the cover was altered to clear it.



#13 Dusky

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Posted 26 October 2014 - 02:01 PM

Well, ou rmustang does the same thing and people adviced the exhaust manifold gasket ( when th eengien works it pumps more air etc, so maybe a higher chance of air escaping via a bad gasket?)

Anyway, our problem is the headgasket :P



#14 Archived4

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Posted 26 October 2014 - 05:14 PM

Will have a look at the exhaust manifold gasket. But still doesn't explain the rev counter going nuts lol






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