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Renault 1.2 8v Tapping (possible piston ring)

6K views 15 replies 7 participants last post by  olds98 
#1 ·
Hello, Would welcome some help on this one, if any one has a clue to this problem. My 1.2 8v engine has a tapping noise coming from what sounds like the rocket cover. Today i took off the rocket cover and ajusted the valve clearances to the specifications. None were way out only slightly. But i ajusted them anyway. Put every thing back together, but the tapping is still there. It sounds like a single tap, and gets no better with temperature rise. Tapping increases with speed, but seems to die out slightly above 3500 revs. Could the problem be a brocken piston ring? If so how do you locate the right piston. Can the piston be removed, with the sump removed only, or does the cylinder head need to be removed.
 
#2 ·
I doubt very much that it is a piston ring,but if it is the head and sump will need to be removed to replace them.:(

Have you tried an oil flush and filter change?.I think that would be the next thing I'd try.

How many miles has the car done?.
 
#5 ·
Thanks for getting back to me. The valve clearances were done with a stone cold engine, using the E1-E3/A1-A3 etc marks on the cam shaft sprocket. After ajusting i turned the engine over and checked them all again. All spot on. Engine very clean inside no black sludge or carbon deposits. Also this tapping has been there for quite few thousand miles, it has'nt just come on.
 
#6 ·
Tapping

You can use a long screwdriver as a stethescope to try and isolate which cylinder the noise is coming from.

Put the blade on the rocker cover and your ear to the handle and as you work up and down the cover the noise should sound loudest near where the problem is.

One possibility is a sticking valve. Clearance may be OK but as it closes (under spring pressure) it sticks part way and loses contact with its rocker, then suddenly snaps closed.

May not be the problem but if you can find which cylinder, you are one step nearer finding the problem.

HTH
 
#7 ·
Doesn't sound like a piston ring (sorry for the pun).

But a compression test would help, do a test on each cylinder, then put some engine oil down the spark plug hole and rerun the test. if it is a piston ring the compression will be greater, cos the oil will create a better seal.
 
#8 ·
Just to update on the tapping noise. Ive replaced the oil and filters, plus added valve and tappet cleaner. But still the tapping is there. The tapping is only there when you put your foot on the exelerator, release the exelerator and no tapping. The engine is still rotateing at the same revs but no tapping, Could the problem lie with the injection system an injecter or similar.:eek:
 
#9 ·
Wondering how you got on with this Paul, while searching for possibilities with my megane 1.6 8v came across your thread and your last post describes similar symptons to which I have been experiencing.
I have actually removed the head now and was expecting to see a pisto ring sitting on top of one of the pistons but alas no.. because at least i would of known what it was.
 
#12 ·
You wouldn't find a piston ring on top of a cylinder as the ring can't pass through between the cylinder bore and the piston.To see if a ring is broken you have to remove the pistons.As you tap the piston out the ring will fall out in a number of pieces.:)
 
#10 ·
Since my last reply i've eliminated the possibility of the injectors being the problem, Compression is fine. Going to take the rocker cover off again and examin the rockers/cam/rollers. and check the clearances again. It does sound like a single tap that increases in frequencey as the reves go up, possably on or around cylinder 3.
 
#11 ·
Hi Paul, My first thoughts here would be lack of lubrication in the rocker area. Ok so I see you've had services with history but can you always trust the garages? I would check to see if the oil is circulating. If the oil is black change it anyway. My engine is the same as yours with 102K on the clock and the oil is clean and golden. Start with a new oil and filter. If you can do the tappets then this should be easy for you. I recently repaired my car with a broken cam belt. New valves etc but when all was done it started first turn of the key but clattered like hell. It all quietened down when the oil got circulating (new oil of course) and now runs sweet as a nut. If you have circulation problems you may need to go to the oil pump which means sump off (I think) Forget about piston rings. They are not likeley to be your problem and they very rarely fail on modern engines. Hope this helps. Shout if you need any more help.
 
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