Is this chain slap on a cold start?

Any help would be very appreciated!

Sound is ~10Hz and it sounds like a valve tappet or scored cylinder. Should also check for a loose spark plug and the cats. You need to jack up the car and use a mechanic's stethoscope to pinpoint the noise better. Why are you using 15w-50? That's not a Porsche approved oil. Was this sound there before the oil change?

I recently had the same tapping. It sounds like a lifter to me. Mine still does it on occasion but the more I drive it the less it happens. You probably have a partially blocked oil feeder hole in the lifter. Once the oil warms up the lifter pumps up and begins to function again. If it sat all winter it can happen. I too would move to a Motul 5 w 40 oil and see what happens.

+3 for tappet. I would try 0-40 or even 0-30 for a short time to see if it pumps up quicker. The oil in m96 engines does more then lubricate it also acts as a hydraulic oil in tappets and chain tensioners among other things.

My car made almost the exact same noise after I started it for the first time after it sat for several months through the winter. I was pretty concerned as the noise was new but after the car fully warmed up the noise went way and never returned. I had also just changed the oil. My theory is took some time for the oil to fully lubricate all the engine components. I have been driving the car for about a month with no problems and the noise had not retruned. I often have a few seconds of chain slap as oil pressure builds. I have read that the chain tensioners are hydraulic and the oil pressure needs to build for the tensioner to work. My cold start chain slap is not the same as your noise. I use Red Line 0W-40 oil and am very happy with it. I recommend staying with the factory specified oil weights no matter the brand. I think the oil you are using is too thick when cold (on startup) which is why it is rapping so long until your engine starts to get warm

As described above, my understanding of tensioner related chain slap upon startup is that the noise is quite loud immediately and goes away (or nearly so) within a few seconds at the most. At least that is what I experienced on my '01 3.4L C4. This noise happened at every first startup of the day and it was worse the longer the car sat between startups. After the engine had already been run on a given day, subsequent startups did not produce the chain slap, or if so it was so brief that it was nearly indistinguishable from the initial "roar" of startup. As others have said the noise in the video sounds like a lifter. I have a 987.1 Cayman 3.4L that produces a similar sound. The noise is intermittent (happens infrequently), is more likely to occur the longer the car sits between uses, and goes away in 2-3 minutes. I have always used Mobil 0-40 in all my modern-era Porsches. As others have suggested, try running a thinner weight oil (0-40 or 5-40) and see if the noise changes. You can watch your oil pressure for signs of the oil getting too thin and change to a 5-50 if necessary.

On another thread I believe that you mention that you recently bought this car and it had an oil change to Motul 0-40 just before you took possession. Do you know if it sat for long before you bought it? Are you driving it everyday? My 2003C2 has a tappet that is slow to pump up, sounds like yours, if it sits for a few weeks during the winter. During summer when it is driven almost every day it is quiet.

Was this car driven this past winter, or stored?

Yes, Jake, the car was purchased by me in December 2014 with 86200 miles on it. I drove it through this last winter, oblivious to the stress of multiple cold starts on the M96. The car had Motul 5W 40 oil in it at that time. Thinking that I was protecting the engine for summer driving, I upped the weight to its current 15 W 50, also Motul. The tapping is more prolonged now, since adding the heavier oil. Today I will change back to Castrol Edge 0W40 and see what happens.

The rhythm that I hear is NOT a lifter. All the proper constants are in place for a classic cylinder failure. Before you spend a dollar on a lifter job, you better get some trained M96 ears on this one that knows the differences in the sounds and where they are generated from. The higher visq oil is making it worse for a reason, which is another constant with most cylinder failures. Approach with great care.

Well, that is reassuring... I will change the oil back down to a zero weight and new filter and I guess we'll just see what happens. My impression of the independent Porsche mechanic that I have been using is that he is quite competent with the M 96 engine. Whatever is happening with my engine would seem to be in the initial stages. Two days ago, I posted on my other thread that he had the car up on a lift, warm and idling. He used a mechanics stethoscope and listened in multiple places on the engine. No obvious source was found. If I have scored one or more of the cylinders there's not much I can do about it. The brutality of the cold temperatures in February does give me concern. I wished that I had been warned in time. What confuses me is the fact that the start up noise that I recorded on video and shared here, virtually disappears when the oil has circulated and warmed slightly. If there was a defect created in the cylinder wall of one or more of them, why would the sound decrescendo and finally go silent? I will change the oil back to an approved (A40) Castrol Edge 0W40 this afternoon keep you all posted. Pensively, Bob

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Yes, very initial, thats why the heavier oil aggravated it and made it apparent. YES THERE IS!!!! Why? Because the first thing that occurs during a cylinder failure is actually a failure of the piston coating, then piston failure, then cylinder failure is collateral damage from that. We have saved several engines from this in the past when caught early on, before cylinder damage occurs This is a super critical stage of the failure. If you change the oil and the noise goes away, trust thats only temporary and may give you false hope that the noise is gone for good. When the noise comes back, it'll be too far gone to repair it by swapping/ coating pistons. This one was properly diagnosed and caught in time to be saved. Time isn't on your side. No noise is a good noise when working with an engine. Please don't drive it to death.

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Jake is not often wrong. You have a chance to save your engine.

Your Rennlist membership fee just got reimbursed by Jake's free advice. Good luck.

Ok. What would be the definitive method of diagnosis short of dropping the engine and removing the heads? Is there a way to be conclusive without disassembly? Is one way to remove the oil pan cover and scope the cylinders to check for any streaks?

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Hi Jake, As I posted, I think my car (2000 C4 with 58k miles) made a similar noise, but only once, on a cold start after the car sat for a several months. I THINK it was the same noise but I can't be sure comparing a video on line to the actual car... It went away after the car warmed up and has never returned. I also had the IMS bearing replaced with the LN Engineering parts and installed an IPD intake plenum right before I put it away for the winter. I have been driving the car for about a month (spirited street driving only) and it has never driven better, its just been great. Is there anything I should be doing other than "shut it down fast" if the noise returns?

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Jake, What is it that we are hearing when there is a cylinder failure? In other words, what is making the noise? Also, why would higher visc oil make it worse? And finally some questions that have bothered me since I've first heard about bore scoring - -Why are we seeing/hearing so much about bore scoring now, 10-15 years after these cars were built? -Why did we not see and hear of this the first, second, or at least third winter these cars went through? Even if there were failures that were covered under warranty (should have been), what about the 6th,7th, 8th, etc. winters after warranty? TIA

This is NOT a new failure and we've been seeing this from the beginning. The difference once I connected it directly to cold weather operation, I didn't share that for years. Many of these filures were misdiagnosed as other issues in the early days (just like they are today), but when a lifter job didn't fix them, the engine ws just exchanged and was never torn down. No one learns anything from changing engines. We don't do that, we get to the root of the problem. I'll reply in detail and answer each question later tonight. I was forced to go to the beach for something called a vacation, and wish I was back in the shop finishing the 930 engine.

Jake, I can't tell you how appreciated you are by us anxiety-ridden M96 owners. You have made it your (current) life's work to service and support this particular ilk of Porsche owners when the company itself has simply kept its secrets, retrieved the damaged engine and charged the warranty-less owner more than the current price of their cars to replace the engine. I think your contribution reflects a passion for the car and a deep integrity that you extend to us. Your work isn't cheap but you quality isn't either. I will get to the bottom of this issue as best as I can here in Rochester. I think my guys at CDI in Victor, NY are competent and fair and honest. We will go from there. BTW, the engine has become more quiet with the 0W 40 Castrol Edge replacement oil from this afternoon. Thanks, Bob [phone removed]

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I hear you!!! I would rather be working on a motor vs being at the beach any day of the week. Thanks for your time, patience and guidance as we dedicated 996'ers try to keep our cars on the road and enjoying them.

Vacation has been tiring... Disney and my 3 year old about killed me today. I'll try to find some time to get some details together in the coming days. Its about all I can do just to keep up with my office work and email from here.. Don't ever own a business, unless you want to take an IP phone with you just so you can keep up with the chaos.

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This is funny, I own an association management company for managing professional and trade associations. I have an IP phone at the office and house and both also ring to my cell phone. Sometimes there is just no escape.

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The only place I don't have an IP phone is in my R&D lab. That building is 2 hrs away from the main shop and the only time I turn on the wifi is during class weekends. Otherwise I have zero contact with the world as there's no cell signal or land line.

I just picked up my car from the Indie mechanic who started the car cold ( I left it with him overnight) The noise began five seconds after ignition and lasted just under two minutes until the engine was absolutely noise artifact-free. I authorized a leak down test and the pressure loss scores ranged from 8 - 12 %, the highest on cylinder 5. He scoped the cylinders while the plugs were removed and found no evidence of cylinder scoring whatsoever. He suspects a timing tensioner on the right bank. I note that Jake's order of cylinder failure sequence begins with the piston coating beginning to deteriorate. There is no way the tech could see that with the engine intact in the car. If I want to proceed further, the engine would need to be removed and disassembled. I do not think I am at that point now. Since there is no loss of power, no smoke, no CEL, trace particles (numbering 5-6 glitter sized particles in the filter paper pleats on the first oil filter change and no particles on the second oil change when I erroneously added 15 W 50 for a few days...) to spend thousands at this point seems unnecessary. Famous last words, but I have a son to help with getting through grad school at Juilliard and NYC is not a cheap place to live! All Porsche owners must assume some monetary risk, have a maintenance account for unexpected issues, do as much preemptive work that they can afford and drive the damn car! Bob

12% is a lot for an M96 engine. I bet he performed the bore scope test by accessing through the spark plug hole. If he did this he DID NOT see the full picture. Cylinder scoring starts at bottom dead center. The only way to see it is by pulling the sump plate and moving the piston to TDC, then maneuvering the bore scope through the bottom of the cylinder. People that don't know this engine fail to find this wear all the time because they don't inspect the engine correctly. You should not have to tell him these things. If you do he doesn't know the M96 as well as he should to be doing this invasive work. If you have 12% leak down on #5, then go deeper on that cylinder and see what can be found. Give me 45 minutes with it and I'd find the issue. No disassembly necessary. Your explanation of the noise continues to sound exactly like a failed cylinder.

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Jake, you said the scoring starts at the bottom dead center. Is that because the rod angle is the most severe (not parallel to the piston's line of motion) at that location so it's exerting the highest thrust load on the cylinder wall?

The rod angle exerts the most force at mid bore. The issues start at BDC because the skirt dwell time is the longest there and because that's the portion of the cylinder that warms up last. This means the cylinder stays contracted most there, aggrevating the issue even more. There's not one single thing that leads to these cylinder failures. The issues have several contributing factors and one of those has proven to be winter blend fuels. As fuels have seen more and more ethanol we have documented more and more failures.

Thanks, Jake. That makes sense.

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Bob, I may have a similar sound on cold start, sounds like a loud popcorn machine. Your video is no longer available on youtube, if you could repost it would be much appreciated. .

If the engine is in process of "cylinder scoring failure", should we see something in a dissected filter and removed sump plate? I would not have a problem making this a routine thing at 3-4K oil changes.

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The debris generated by this is very fine and hard to see. The only thing we find in oil that's if notable size is the iron skirt coating and that's very seldom. Like most failures, by the time debris is found the engine is already compromised. fine debris is more damaging than large particles as it suspends easily in the oil and is delivered throughout the engine.

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So, are you saying the debris is so fine it is not trapped by the oil filter and continues to circulate constantly through out oiling circuit?

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Sometimes the debris doesn't see the filter and is circulated int he splash oil before it ever sees the oil sump. Keep in mind that oil goes through the oil pump first before seeing the filter, so debris will take the oil pump out and create collateral damage even with the best filter on the planet. Also, the stock filter housing has a bypass and every time the engine is cold started or sees more than 4.8 bar oil pressure a portion of the engine's oil is bypassing the filter and going straight to the primary oil system. Its a horrible design.

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Isn't that a more normal design for an engine and oil filter?

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No, the oil thats bypassed should be directed back to the oil sump, where it can be recirculated and then filtered. Bypassing the filter is just plain stupid.

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Then wouldn't you be running low pressure on cold oil?

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No, because this is BYPASS oil, the oil that the pressure relief setting has indicated as being too great. This is done to keep the factory filter from collapsing due to too great of pressure. The issue is, when a filter collects debris and becomes slightly restrictive, the pressure relief will pop sooner. This is a double negative since debris is what makes the filter clog, so the more debris it collects, the more bypass oil is generated. That bypass oil is debris laden and goes straight to the rod and main bearings. This only makes sense to an accountant.

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Edit: "...to a short sighted green visor wearing accountant" Some of us do have mo better sight- I felt the need to defend our knot + knot profession a bit...;0

Jake- Thanks for your insight on this thread, it was very informative to me!

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My wife is an accountant.. Probably the only female in the profession that holds 4 Land Speed Records in a 911!