Engine Oil Filler Dirt

Hi All, Having just had a look at the oil filler pipe for my C4, it has a nasty covering of dirt and grime/bits which I can't imagine does the engine much good. I cleaned around the top with a rag and the cap itself, but am wary of cleaning into the flexible pipe as dirt could get into the engine itself. Has anyone seen this before and is there any method for cleaning this or it is best to just leave it alone? Thanks, Steve

Do you mean mayo-like substance? If so, it is just an emulsification of water vapour and oil mist that collects in the tube, and is very common. If you mean dirt - the abrasive stuff - then it needs looking at. I've never heard of it before.

Hi Richard, I would describe it as a covering of oil with small mineral/dust particles (old mineral based oil i guess which was never wiped away and dirt has stuck to it) which are quite well stuck to the solid plastic pipe itself. There is no mayo type stuff at all. Looking down the tube with a torch it looks clean further down into the flexible pipe, just dirty at top of the pipe where the cap is. Strangely engine itself is fairly clean, but not has not been steam cleaned in a long time judging from build up of general dirt in the engine bay. Do you think a Indy would be able to clean it up without it getting into the engine? Thanks, Steve

I can't think why dirt has got in there in the first place. It is quite a lot of faffing around to remove the filler tube. The airbox, throttle body and centre air distributor have to come off, and the alternator swung out of the way. Book time is about 1 hour & 40 minutes. If it is clean further down the tube, I would just work at it bit by bit with some paper towel on a stick, trying not to let anything fall down the tube. Personally, I would want to get it out one way or another, rather than it get washed down into the sump by oil fills or top-ups.

Thanks Richard, I would say the oil residue is quite well stuck to the plastic pipe and I had to really scrub the pipe to remove it next to the cap. So normally you would not expect to see any oil residue at all on the plastic pipe at all - it is perfectly clean even on the older 911s? It is definitely old mineral oil (judging by smell of my hands right oil)..... I will try the cleaning bit by bit option i think, but am worried that some of the bits could fall down into the sump during my cleaning. Thanks.

Silly question, but anyone confirm if there is 1 or 2 oil filters on the 3.4 996 (1999) engine and should both be changed under a 24k service? Does anyone also have a list of standard items to be changed at a 24k service for reference? Thanks, Steve

There is only one oil filter, and the service schedules are outlined in your maintenance booklet. Complete maintenance schedules and part numbers for service items are available for PCGB members in the Technical Articles section of this forum. [ ] [ ]

Thanks Richard, Slightly dissapointed as the knocking noise at hot idle returned and I am trying to figure out where to go from here... I am a little worried about looking at valves, tappets etc when the engine is running perfectly except for the knocking noise at idle (and only once engine has been running for a while). It never happens on startup. Could lifters/broken valve spring be a possibility?? Is it likely to be damaging the engine having this noise at Idle? you can hear it above the engine noise at idle when standing at rear of the car, but oil pressure is perfect. Thanks, Steve

It could well be a tappet. I would have thought that if it was a broken valve spring it would happen when cold, and at all engine revs. What oil are you using? If it is a 0W-40, you might want to try a 5W-50, which might give you a bit more pressure at idle when hot.

The car was recently major serviced by Paragon in Sussex who couldn't replicate the noise after the service and gave the engine/car a clean bill of health - they seemed to think fresh oil would do the trick. Must say I have been impressed by their info/customer service. Service details show: mobil synt s 5w-40 It is actually running at quite high pressure especially when cold (5 bar) dropping to 1-2 bar when hot on tickover, so maybe the lower pressure when hot is the issue.... Paragon suggested a lazy tappet, but my major concern is would this be causing any major damage to the engine if the tappet is making this noise. Also can individual tappets be replaced in 3.4 engines if the noise could be isolated. Thanks, Steve

5W-40 is the same viscosity as 0W-40 when hot. That's why I suggested 5W-50. 5 bar when cold is normal, as is 1-2 bar when hot. I think Paragon are correct, that it is a lazy tappet, so the thicker oil may help. Porsche approve Mobil 1 5W-50 for worldwide use, so it won't do any harm to give it a try. Worst case, yes the tappets can be changed individually, and an indy will do it with the engine in place. I would doubt that they could track it down to one particular tappet, but if it is present when they look, then they should be able to hear which bank it is coming from. The tappets are £30 each, and there are 12 on each bank. Plus labour and gaskets, etc.

I do wonder whether it will settle down by itself. Assuming running it as is, is not doing any damage to the engine it seems to make sense to see if the individual tappet can be identified by an Indy. Strangely it first happened after a 250 mile run including 45mins in a traffic jam although the engine temp stayed perfectly normal throughout. Thanks for your help - it this a typical issue on 3.4 engines specifically?