[aag]

There is a "clicking" sound that is coming from my 968 engine and the frequency increases with RPM. It sounds very much like it is coming from the valve train (and reminds me of the sound one would hear from a mechanically adjusted valve that is too loose). I think I have isolated the sound to the rear exhaust valve (using an engine stethoscope) and assume that the sound is due to a failed hydraulic valve tappet <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" /> . Before I order new tappets, does anyone have any experience with these tappets failing or could it be something else? Thanks for your help.

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[968workaholic]

Has the car been sitting for awhile and this just started? Often with these engines the lifters bleed down after a week or so of not being driven. The good news is that after driving them for about 30 minutes they pump back up and the noise is gone. If that doesn't fix it, then one of them probably blew a seal and isn't holding pressure.

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[968rz]

+1 on the lifter bleed, my will do this (especially if the front is on stands for a bit). I just let it run a few seconds shut it down and restart it and the noise is gone. If it never stops and the oil pressure and level are good I would think collapsed lifter or broken spring.

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[PhilG968]

[quote name='aag' post='42693' date='Oct 21 2007, 08:46 AM']There is a "clicking" sound that is coming from my 968 engine and the frequency increases with RPM. It sounds very much like it is coming from the valve train (and reminds me of the sound one would hear from a mechanically adjusted valve that is too loose). I think I have isolated the sound to the rear exhaust valve (using an engine stethoscope) and assume that the sound is due to a failed hydraulic valve tappet <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" /> . Before I order new tappets, does anyone have any experience with these tappets failing or could it be something else? Thanks for your help.[/quote]





Hope its not serious, I had a clicking much like that one afternoon, and my timing belt failed while trying to start the car afterward. Valves were clicking, got lucky no damage.

I'd check your belt too.

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[aag]

[quote name='968workaholic' post='42694' date='Oct 21 2007, 09:04 AM']Has the car been sitting for awhile and this just started? Often with these engines the lifters bleed down after a week or so of not being driven. The good news is that after driving them for about 30 minutes they pump back up and the noise is gone. If that doesn't fix it, then one of them probably blew a seal and isn't holding pressure.[/quote]



Hi - and Thanks. The car has been sitting for about a month so you are probably correct. It was still up on jack stands since I had just finished changing the oil and filter and then started it, which is when I heard the tappet noise. What I did not realize is that these hydraulic lifters actually bleed down. I thought they were sealed units with oil in them. It is still not clear to me how they "recharge".

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[968rz]

Engine oil pressure just pumps them up.

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[4matic]

I used Rislone. Tapping gone.

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