Noise after cold start

So, yet another noise thread.... Its been quite cold spring here and my -98 C2 has been making some ticking after cold start. Engine starts with no ratles or tick tocks, but after 10 sec noise starts. sounds like lifter, but rpm has no effect to frequence. If I raise rpm about 200 up from idle noise goes away. And returns after 1-3 sec when back at idle. Out side temp has direct correlation to the symptoms. Colder means louder and longer noise. This is not my vid, but same symptoms.

Not sure if the video works, lets try again https://www.youtube.com/watch?v=37OKzG78WSA

Ahh, the very same noise that keeps me up at night and taking my car to different techs. Unfortunately, I bought my car in the summer, so I never really heard this noise until September when the mornings started to cool off a lot. I recently picked up my car from a tech who checked everything possible to find out why it was making the noise. This tech was expensive, but he has a great history of over 40 years with Porsche and learned everything he knows working for the racing team in Germany, so I trusted him very much. He drained the oil, removed the sump and found what he described as the cleanest engine he has seen on a 19 year old Porsche. He said there was no evidence of any debris and it was apparent that the car had frequent oil changes. He borescoped the engine from the bottom and found no scoring. Both good signs. The engine runs very well after only a minute or two and continues to run well on spirited drives of any distance. There were no loose spark plugs and he did not think the chain tensioner was causing this noise (that should only last a few seconds). His final diagnosis was that is was piston noise and he thinks it may be a "lazy" MAF that is causing it. He told me to drive it home and enjoy it, but keep my eye out for any MAF sensor codes. When I bought the car in July, I had a fully intrusive PPI performed at another very reputable shop. The car was borescoped then, also, and they could only recommend servicing the IMS bearing for $4000... I declined. It seems everything about the engine is mechanically perfect, but I still cannot stop worrying about it. Like Jake says, no engine should be noisy, even if intermittent. I am surprised by the amount of posts regarding this issue that I have found here on rennlist, and not even one has an explanation or conclusion. All the threads just stop.... One last little point. This particular noise that our cars are making appears to only happen on early 99 and 98 cars. Every thread, video, or person I have talked to that has this exact noise with the same characteristics is driving around in early builds. I find it very interesting. I hope someone has even a little more information so we can pinpoint what this problem is. Mason

Thanks Mason, On the video comments, there is one german owner that says the noise is coming from the oilpump. That the pressure release piston in oilpump is knocking when the oilpressure is high. I have new oilpump thou, well 4 years ago, so not sure if the model year would have any affects. But it might be same pump that the original was.

My 99 C4 makes this same noise when the ambient temps below 60 F or so. It's a later build, I think it was made in 3/99 or so....would have to check. Another lister came over to my house last weekend and said his 99 makes the same exact noise. The quicker it gets some heat into it, the quicker it goes away. I just drive away. I'm not loosing sleep over it.

Sorry, I just meant 99s and earlier model year in general. It could very well be a coincidence, but you and someone else having a 99 that makes the noise seems to show earlier 996s are the most susceptible to this issue. Good to hear someone else living with the issue and having no other problems. How long has your car been making the noise? My tech said he has seen cars make this noise their entire life with higher mileage.

I've had my car since November 2014, so a little more than 2 years. I don't drive it in the winter, it's just in storage. I did not notice this until a few weeks ago on a 40 degree day or so when taking it out of the garage. I don't know if it made the noise previously, but I just recently noticed it. The car presently has 46K miles, I bought it was 31K miles.

Use 0-40 oil in cold weather??

I have DT40 in my car. Put it in just after I got it. Will be sending out the latest oil sample that I took a few weeks ago for analysis....but the filter and magnetic drain plug were clean as a whistle.

I also use DT40. Did not do a sample yet, but I probably will next oil change. During the PPI they did some kind of test of the oil, although not a proper analysis, they stated it was clean of debris.

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Have you checked if the cats are rattling? Good oil pressure at idle? It would really help if you can upload your own clip.

I read translated that comment and it is interesting and it completely makes sense. Unfortunately, it has been a much colder than usual May, but once it gets warmer I am interested to see if the noise stops all together. I have not had my car a full year yet, so I am not sure if the noise will go away once it is warm. It is weird, even now when the mornings are 45 degrees, the car still starts sometimes with no audible noise at all.

Another thing to test. Does the noise go away with clutch in and transmission in neutral.

I recorded a cold start up just for fun, and got extra footage my dog's butt on accident. Sorry, I know that's not helpful.

Check all of the fans. I thought I had something going on a year or two ago; turns out the seed ball from a sweet gum tree found its way through the wing opening into the fan shroud for the engine compartment fan. When it would spin up, seemingly scary noises were produced.

I am not OP, but just to clarify, because it appears we have the exact same noise based on the video and his description of the noise, here is everything I can say about it: 1) The noise does not go away whether in neutral or with the clutch depressed 2) The noise definitely changes with outside temperature (slightly louder and longer duration when cold) 3) The noise will go away when the gas is blipped even as little as 200 RPM as if it smooths out, but does come back after a few seconds. No change in frequency. 4) I have never heard the noise while driving, after a drive or after consecutive start ups throughout the day. The car really has to sit for a while before it happens again. 5) Oil pressure is perfect and idle is as smooth as butter. Tech confirmed my car felt absolutely perfect when driving in city conditions and spirited. Again, I am not OP, but I can be certain these are the exact same symptoms OP is having. The video posted really does display the sound perfectly. The sound is all too familiar to get it mixed up with another issue.

Check the cats

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Yep, exactly like you describe. I allso have litle heavyer 5-50 motorsport based oil.

My 1/99 C2 makes the exact same noise as Paul's. Sounds like a piston slap or faint rod knock or wrist pin or chains, who knows. It only happens on a cold start and goes away in 1-3 mins. If I carefully drive it slowly, it goes away faster than if I just let it sit and idle. I'd rather get the oil flowing and heated. It actually sometimes sounds like more than 1 piston and even sounds like a rattle. Sounds scary, but... Honestly, I wouldn't worry too much if it goes away in a few mins. And keep the ear out if the sound changes over time or gets worse. I think it's important to get the car warmed up fully before putting the hammer down. Here's a link to a video with my car's cold start noise: You Tube

Ok, tapped the catalysators with my hand this morning. Right side cat did make some noise, but I couldnt pin point the source. Left mufler did make some loose baffle ratle. murphyslaw1978: Sounds like the same noise. Does your car have the same symptoms that twitchett posted? It seems that the noise is getting quieter as my oil is getting older. 1500kms after oil change. Outside temperature was 32F this morning. Yep... So it could be the oilpump, or piston slap caused by the heavyer/stickyer oil. And why the 5W50 motorsport? The chain noise on hot start is allmost non existent. Planning to open the engine (again, last time was 90k kms a go) next winter for changing the all the chains and ims paddle.

It's very easy to pinpoint such an obvious noise. Just use a mechanic's stethoscope to poke around the suspected areas when the car is making that noise. https://m.harborfreight.com/mechanics-stethoscope-69913.html?utm_referrer=direct%2Fnot%20provided

Yep, will test that.

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I have the exact same noise, if not very very similar. I spoke with a reputable Indy Porsche mechanic where I live and he was not too concerned. He stated lifters and piston noise would go up with the RPMS. Mine does not. He suggested possibly a bearing noise coming from the water pump since the noise goes away after about 30 seconds. I'll be keeping an eye on the water pump for coolant leaks, but so far I have not seen any.

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If your does not go up with RPMs, it�s probably not the water pump. Could be cats, cold air/secondary air motor or something else. By the way, it�s been over 3 years and 15,000+ miles, and my car STILL makes this cold start noise, but if I drive off immediately, it doesn�t happen. So I drive off immediately, always, lol.

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For what it�s worth, but car made the exact same noise as Mike�s and I never had an issue. I put on 17,000KM and when F6I opened up the engine they said it was rather clean. Wear expected with the mileage the car had at the time. Just drive it!

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Thanks, that helps. Although I have gotten past the sinking feeling that something is terribly wrong and instead, I don�t worry about it. Some of the early 996 turbos sound terribly noisy right after cold start, and although that�s a totally different engine, I suspect some of these noises might just be common in some of the early cars. I�m sure some customers may have complained and Porsche would have to certainly fix it, even if nothing is actually radically wrong. The design of the 5-chain engine and tensioners isn�t the best, and so improvements have been made. The old saying �buy the newest 911 you can afford� is often the best advice, as Porsche makes sometimes dozens of small improvements over the years of the same model designation. IMSB changes from 00 to 05 notwithstanding, they usually get it right. Speaking of which, I can�t wait to see what the 992 GT3 is actually going to look like and drive like.

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If it�s the cats, hopefully it doesn�t create a smog issue. This next year will be my first time smogging.

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If you poke around YouTube, Chris Harris got a pretty darn good look at the new GT3. The good parts are that it will still be a NA screamer and come with a manual option. I think they further increased the front track at the expense of the car getting bigger but not much of a weight penalty.

could be a slight exhaust leak that seals up when it gets some heat and expands shut

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If it�s cats or the muffler, I�m guessing it�s a loose piece somewhere that doesn�t affect the operation of these units. But I don�t know because Illinois doesn�t sniff the exhaust for emissions testing.

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Yeah, I saw that video. But want to see more!