Porsche Enthusiasts Club Forum

I don't always get this, but noticed it again this morning. Only happens from cold (i.e. 5:30am starts), and once the car is warm it stops.

Sounds like lifter noise, but rather than being a constant tap until they have pressurised, it will tap but then sometimes will come and go, almost like it is cyclic.

I'm almost certain this has only happened since an oil change, but I remember the previous owner saying he found it sensitive to oil type i.e. tapping on startup. I used Shell HX7 10w-40 with mahle filter.

Thing is, as I understood it, a lifter will tap until filled with oil, so why would it come and go? Does this mean it's likely to be something else? Oil pressure is full scale when cold, around 3-3.5 bar warm idle and runs fine otherwise.

I know it's not likely to be a big deal as it quietens down when warm, just the way it comes & goes seems odd to me.

Any ideas?

Possibly just a sticking lifter, there have been a few threads on here in the past re this, IIRC an engine flush may cure, otherwise you may need to replace the lifter(s)

Yeah, I expect it is just that, as it did clear quite quickly today and didn't come back. It's just odd how sometimes you can startup from stone cold, have no noise, then it will start to tap, then go away, then come back, etc.

I was always thought that once a lifter was pressurised it was quiet, but I suppose if one or more are sticky then they may be only partially pumping up initially.

I think I will try some engine cleaner first. I have heard good things about Forte top end treatment. Not sure if you can still get it though? A mechanic friend of mine offered me a bottle of Forte engine flush, but it would mean dropping the oil again afterwards, but I've only just replaced the oil & filter. I think I read that the top end one can be left in.

Hi Andy, Once I got my S back on the road I too noticed a tapping sound that started from cold and then went away once the car warmed up. It had a distinct sound similar to dropping a marble on glass! I seemed to come from the top of the engine, but it was difficult to pinpoint exactly where. It was not a clatter (tappets), it was not the injectors, and although it was cyclic it wasn't continuous, it would come and go. Does this match your symptoms?

Anyway, as I didn't want it to go untreated I decided to take off the belt covers first and just check that everything on the front was OK. I started the engine and watched...what was actually happening was the cambelt was vibrating as it left the cam pulley and hitting the cam cover and the water pump guard fence. This was causing the tapping sound, basically the belt needed re-tensioning as it had stretched slightly. However, as the engine warmed up the tapping became less - as the alloy block expanded and took up the slack in the belt.

So, did a re-tension (purely by feel) and the sound has not returned...but I may have tensioned it just a bit too much as the belt now whirrs a bit like a washing machine.

If you think it might be this listen carefully to where the sound might be coming from, use the old screwdriver against the ear technique, or if you have a stethoscope so much the better. Obviously be very careful around the rotating bits!

All the best, Rhett.

Had exactly the same problem with my S2 cam belt had loosened off and was catching on the cover, don't think it was the belt going slack more the tensioner not being done up tight as the car had only done about 500miles since belt and roller change.

Thanks for the tip. It's something to double check, although my engine does whine a bit when on the move which has always lead me to believe the belts might be a bit on the tight side - but I'll take a look anyway.

It's not done it since - typical!