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Long story short, left car at well known exhaust place to get 1inch added to the length of the exhaust. Picked it up just now and first there are 8kms on the odo which the owner swears on his life he didn't put on there (where the eff did they come from then bud!?!?), but also there is a very loud knocking sound coming from the top of the engine. I put my ear to the cam cover and it sounded like it was hitting the cam cover. The sound was exactly the same kind of tick tick tick that you get when you put a stiff playing card in the spokes of your bicycle. I was talking with the owner of the shop for half an hour while one of his customers him and myself were playing with the revs, turning it off and on again, trying to work it out. Needless to say the car was more than warm enough while it was still happening. After a while it got a bit quieter (when the customer was unplugging spark plug leads to determine which cylinder, or rough location), but it was still present. I didn't have any other way to get home, so I drove it home (hour trip), and by the time I get home you can barely hear it, but it is still present. I have parked it for the night, going to try it again tomorrow when it's cold, see if it is still doing it. The oil was changed less than 500km ago, and it has never presented with this sound before, even from the countless cold starts that it has had, and from its weeks of inactivity. Any suggestions?

Is this an NA? Sorry, too lazy to go back and search your posts or your garage to find out... ;)

If it is, you could be hearing a lifter that has bled down. However, if you own an NA, i'd be mighty surprised if you had never heard that noise before...

I am also surprised that it is still making the noise after an hour of driving.

Sorry, yes NA6, and it has had a 100,00km service done by mania like about 5000kms ago. Oil is 5W30 Castrol sport, and as said was changed <500km ago

very thin oil = cold start tappet noise. if you go thinner than the original recommend, then it'll happen more. although you say you haven't had issues before. so dunno?

But it has never happened before, and I have been using this oil since I got the car. It also persisted for a long time, much after the engine was warmed

I have the same problem (however, my HLA's clogged up because I didn't really drive the car for 6 months). Correct me if I'm wrong but there is a product you can run through the engine to help 'clean out' the HLA's? Either that or it's time for a solid lifter conversion

As NA engines age, they start to get a cold start rattle. Generally it will disappear after warming up but it can persist. I hope this is all it is

Is the car running OK? No new misses or roughness? Those sorts of noises can come from things like sheared cam lobes, dropped valves or broken valve springs: all possible consequences of having the guts revved out of it.

Car is running fine, no real issues apart from that loud noise on startup. So, okay, it is a normal issue for older engines. Mine is not old! It has had all of its seals replaced not long ago, and it has less than 100,000kms on the clock (even once you take into account that it is an import and the odometer never tells the truth), so why happen now?

mitch_f1 wrote:Car is running fine, no real issues apart from that loud noise on startup. So, okay, it is a normal issue for older engines. Mine is not old! It has had all of its seals replaced not long ago, and it has less than 100,000kms on the clock (even once you take into account that it is an import and the odometer never tells the truth), so why happen now?

Just because the seals were replaced does not mean the engine is "new"
to make the engine "new" again, you would need to replace the rings and bearings in the pistons & overhual the tappets, with a machining of the block.

the noise is probably just lifter related, id suggest a thicker oil, 5-30 is a very thin start up, more for high end powered cars (imo)

Fair call. What do you think could have called it though?

old engine as that is what is it.

seems to be a general consensus that the oil is too thin. 10w-30 10w-40 15w-40, the last 2 being options better suited for older engines.

Okay, so I should change the viscosity of my oil, sure. But please can someone explain why this has happened now, and not after any of the 4 prior oil changes in the last 2 years, with a little over 10,000kms done since the first.

IF it is a tappet / lifter related noise, then you just answered your own question. The engine is 10000km older than it was. The oil change just brought it on. I find my car is noisier with certain oils over others.

Change your oil to a good quality 10 or 15w40 synthetic or blend. Change your filter at the same time and take it for a good blast somewhere fun.

If the noise is still there, or getting worse, let us know.

Good luck

mitch_f1 wrote:Okay, so I should change the viscosity of my oil, sure. But please can someone explain why this has happened now, and not after any of the 4 prior oil changes in the last 2 years, with a little over 10,000kms done since the first.

Couldn't have anything to do with this?