Knocking noise advice please.

[MMT]

Any ideas what this knocking could be please. It's a 2000 Carrera 4.
http://youtu.be/D9MXGtoEd0Y

[monthefish]

Sounds too low a frequency to be directly in the guts of the engine, sounds more like a secondary vibration from something surrounding the engine (but I'm no expert - be interested to hear what the experts think)

[Pope]

Sounds like a tappet issue to me from the short clip.

It's metallic with a ring to it - like a clearance is too great. Has it been sat for a while without running (week(s) rather than hours)? If it has lift the revs up for a while and it should jack the tappets back up with an bit of extra oil pressure. If it has occurred suddenly, then it may be more sinister. Check your water pump and or header tank too - there is a bit of moisture on the lower pump hoses in the vid.......

[monthefish]

Pope said:

Sounds like a tappet issue to me from the short clip.

I thought the frequency sounded too low to be tappety, but I could be wrong.

[MMT]

It's a car I've been to view today. No mention in the ad about any noise, but does say he thinks the oil cooler is degrading. He told me when I arrived that it's got a lazy tappet. The noise goes when the revs are around 1200, but even after a spirited run the noise was still there. There is also slight mayo in the oil filler cap.
The car has documentation from Hartech covering engine removal, re rounding liners and retaining clips, IMS upgrade and various chains and guides. Head strip, de coke and valve lapping.
That was 3 years and 12k miles ago costing £5k.

[Pope]

The oil cooler is degrading?!? Eh?

The oil/water heat exchanger is there to speed warm up of the oil when the engine is cold and to help cool the hot oil when up to temperature. If it's leaking then OK but they don't wear in a mechanical sense?

I have seen flat base tappets wear right through meaning the oil never takes up the excessive valve clearance as it should, hence the noise, but generally it is too noisy to ignore and without fear of further engine damage.

You can work out if it's crank or valve gear related - count the number of occurrences in a specific time and apply that to the idle speed.

[lukecollins]

Check your oil level and oil pressure, does sound like tappet noise to me. I know some have piston slap. Not sure what noise to expect but may be worth checking for the noise on YouTube.

[lukecollins]

Found this on you tube. Looks like piston slap I am
Afraid. http://youtu.be/LHKPqebCjpQ

[MMT]

Yes I had googled the oil cooler and watched a YouTube clip showing how it could be tested. To me it sounded a bit to loud for tappets, but I'm not familiar with Porsche engines, hence my question on here.

[mollytherocker]

lukecollins said:

Found this on you tube. Looks like piston slap I am
Afraid. http://youtu.be/LHKPqebCjpQ

So thats bore scoring?

[MMT]

I watched that clip earlier Luke and thought it sounded very similar.

[ras62]

Sounds like a bad tappet. Very unlikely to be bore scoring on a 3.4. Get the seller to have it fixed if the car is otherwise good? If it comes from the drivers side bank the its very labour intensive

[lukecollins]

I would expect that if the oil cooler was blocked you would get high oil temps or high oil pressures assuming it's on the pumps delivery side. I can see the coolant side fouling but not the oil side with crap. The noise sounds expensive to me. Does the car smoke under load?

[lukecollins]

I would expect that if the oil cooler was blocked you would get high oil temps or high oil pressures assuming it's on the pumps delivery side. I can see the coolant side fouling but not the oil side with crap. The noise sounds expensive to me. Does the car smoke under load?

[Mark A S]

Any internal mechanical engine tap like that is not good. I would walk away.

[systech]

+1 walk away!

That's way too loud for anything but an issue of concern. Also noticed a fluid leak during the video.