What was that tapping sound?

[mejulihn]

This morning when I started my '76 2.0 after it had been sitting for a week or so I got a very distinct tapping sound from the motor -- much louder than the usual valve train noise when cold. I drove it for about 10 minutes at low RPM's until it got warm and the tapping finally went away. I am running Mobil 1 and the oil level was normal. Should I be worried if this happens again?

[HMeeder]

Maybe an oil passage clogged and didn't loosen up until the oil was warm enough. No oil to some vital motor part. Or perhaps a loose valve rocker causing the pushrod to slap a bit until oil got to where it needed to go? Oil travels through the pushrods to lube the heads.
Herb

[Germain]

The oil idea could be correct. I would look at the consistancy of it. You just may have a valve thats gotten a bit out of adjustment. As the car heats up, the tapping slowly gets softer.

[mejulihn]

I started the car again yesterday and the unusual sound did not occur -- just normal valve train noise. It may just have been a one-time deal. I am relieved!

[John Rogers]

The next time you adjust the valves, check the shims on the rocker arm shafts and also check to see what amount of side-play the rockers have? The side-play should be minimal, but sometimes shims will break or even be left out during assembly and can result in the rocker arm moving off center of the valve stem. Surprisingly this seems to happen when the enging is shut off and will show up when you start the engine next time with a loud clacking and then misteriously dissappear with no explanation, but the rocker has lined back up it seems. This happened on our 1974 914 and when the rockers and shafts were pulled, two shims were missing. Once everything was lined up and shimmed correctly it never happened again. Hopefully it won't happen any more to you as it is scarey, good luck.

[Dave at Pelican Parts]

John, is this a stock valvetrain? Stockers have springs in between the rocker arms which keep them positioned. The later hydraulic-lifter Bus motors have the solid spacers and shims.

The spacers can be fitted to non-hydraulic engines easily.

--DD

[John Rogers]

To tell the truth Dave I am not really sure if they are stock or not. The heads on my daughters car are supposed to be stock 2.0l heads and they do not have springs? The rockers/shafts/etc may have been swapped, but I don't know. I do remember my 1973 bus had solid lifters and it also had springs and not the spacer/shim combo? That is why I did suggest a close visual inspection of the upper valve train.

[mejulihn]

Hmmmm, I have been told by a qualified Porsche mechanic who I asked to do a valve adjust that I do have (non-stock) hydraulic lifters. So now I am confused...

[John Rogers]

NOW, that probably explains it a little better. My daughter's 914 has hydraulics and if it isn't driven nearly every day, then the make some noise when starting up and I noticed it more with synthetic oil so I went back to 20-50 mineral oil and they don't do it much. Hydraulic lifters will tend to loose their oil from drainage and since there is not a huge amount of oil flow to the lifers, it takes a while to pump back up. Your mechanic is correct, hydraulic lifters don't get adjusted like the solid lifters. I would also recommend checking the rockers as I mentioned since a common mod when installing a hydraulic cam/lifters is to remove the springs and use spacers/shims to align things more precise. Good luck.

[This message has been edited by john rogers (edited 09-27-2000).]