Van, Thanks very much for the in-depth diagnostic of the M96 engine.With all the internet,publication editorial and various forums on the web about this particular Porsche engine we can see for ourselves what's happening here.Great piece of machinery and engineering by Porsche in light of the necessity to produce newer and more efficient designs that define what the iconic sports car is all about!
just fyi bore score starts at the bottom of cylinder 6, you really need to rotate piston 6 to bdc and/or look at the underside from the sump to confirm presence of bore score
Thanks for the greatly instructional video. I am thinking about buying a used Porsche so I am learning about their engines. I so like your slow pace and calm voice, the great amount of real content in your videos, a welcome change from all the hype and fluff of most UA-cam car videos. On another note, do you have a recommendation for a good medium-duty engine hoist and engine stand? Thank you.
Cylinder 6 is scored beneath the ring line, it's the piston skirt slapping the wall you can hear. Not the lifters, nothing to do with the heads, the reason the valves are carbonised up is there is oil being burned in the combustion chamber bypassing the oil control rings.
Interesting. I was surprised to not see lifter trickery that allowed the valves to be opened more. I have a 968 head on the bench and its "VarioCam" includes this feature. I guess the big 6 cylinders don't need it! Very cool look inside the 996 engine nonetheless.
It's not an injector problem. If the intake valves were loaded up it would be a different problem and possibly an injector. If the exhaust valves are loaded up it's because there's oil getting on the exhaust valve and or the valve isn't closing all the way because either the lifter is fully extended or the valves crashed into the piston. He needs to put the valve in a valve cutting lathe spin it and see if it's warped. If not put your lifters into advice and see if they're collapsible because one of those two is your problem. Now if the exhaust valves crashed into the piston you have to determine why only the number 6 exhaust valves crashed. It's not likely to be a warm timing chain in this case because you have two exhaust valves on number six that are crashed and no others and it would have been the intake valves that would have crashed if you had a warrant chain. So you're most likely cause his probably bad lifters because their clogged at number six. And just to be ultra clear when I say bad lifter I don't mean that they're collapsed I mean that they're fully extended and not draining.
Enjoyed this video....pity there was not some follow up videos going through fault finding and testing 👍🏻 What was the root cause to the issue with No.6 cylinder?
those valves are not burnt. That appears to be oil fouling from a leaking valve guide or piston rings. that would cause an incomplete burn, resulting in excess carbon fouling. there is the cause of your compression leak. your knocking noise is probably a clogged oil passage, or bad lifter. resulting in lose of oil pressure in the lifter, causing a tap. a tap that you are hearing as a knock.
Van Svenson That's harder to diagnose in a flat engine. The evidence is easily dissipated out through the exhaust. In a vertical or "V" paturn engine you would have noticed a heavy gasoline smell in the oil when drained.
a good clue is how the whole combustion chamber is extra clean.. like its been STEAM CLEANED..HELLO !! There is only one way it would be THAT clean....there was water entering the CC for sure Naturally coolant being burnt along with fuel in the combustion process isnt going to contribute to a quiet running engine..duh i would have to hear the noise before i called that one .. u better thank gawd u didnt have to put THAT engine back together...they sure come apart easy enough LOL
Typical issue for 3.6l 996, 295hp 3.4l Cayman S (pre-facelift), and 3.6/3.8l 997.1 engines. Hartech has made a lot of studying and the reason is most likely poor cooling of the 6th cylinder causing too much heat on it, so the oil looses its abilities to provide lubrication film causing metal to metal contact between cylinder and the rings/piston. There's no easy solution (double up the oil sprays and change head gasket with larger water passage hole for 6th one, which basically are only viable to do when rebuilding a failed engine), but apparently changing to a lower temperature thermostat can help prevent the issue. Doesn't help you, but anyone else there with those engines should seriously consider this.
Just a thought, as cylinder 6 had the classic bore scoring, all that carbonisation could be the oil entering the combustion chamber and due to incomplete combustion of th oil it fouled up the exhaust values on the exhaust stroke, compromising the seating? High oil consumption is one of many symptoms of scoring. My understanding is it’s a very localised coolant rate thing that causes hot spots on the thrust side of cyl 6, causing the bore oil to fatally thin, allowing the piston to fragment bits of the Nikosil liners off on the thrust side of cyl 6. It’s the fragments that then score the liner. I really don’t like those open deck cylinders, they look so thin to my layman eyes :D
@@vsvenson interesting! Once you pulled the piston, was the bore visually bad? Did you get rid or have it rebuilt elsewhere? Keen to hear your thoughts and the outcome... Cheers Russell
Hi Van, given the unfortunately diagnosis (i.e. bore scoring) and knowing the history & investment in this car, would you purchase another 996. If so, what would you do differently? Thanks for all the helpful videos!
RE: Cold weather 996 - is that because of the common issues surrounding driving in cold weather (i.e. salt/sand corrosion) or storage issues? Or, is this based on theories that claim people with cold weather 996 Porsches are more prone to common M96 problems like IMS failure, cracked heads, bore scoring, etc.??? Thank you for your time and advice! btw: I have a southern 996. Live near Jake Raby (Flat 6 innovations) for point of reference.
Hi! Thank you for the very detailed video! I have the same sound but I think it's on cylinder #4, were you ever able to determine what was the cause of the knocking? I'm wondering if I should fix this engine or just replace it. My guess was a rod bearing, but it isn't as loud as I remember hearing it on the inline 4 engine. And I couldn't find the follow-up video.
You mentioned there are no bearings on the camshafts, could it be that the camshaft is wobbling a thiny bit which is just enough to change timing at the furthest cylinder? Just thinking loud here. Let us know the cause anyway.
P3t3rG1 The camshaft bearing surfaces look clean and smooth - if they were out of spec enough to cause that kind of noise, I'd expect to see visible scratching and wear. But keep the ideas coming!
Next time maybe rotate the engine to show the bore score we all know is there is in cylinder 6. It’s 2024 if M96/M97 goes knock knock on number 6 you don’t even need to scope it, just pull it, strip and send it for nickies.
The outcome was scored cylinder walls and piston slap - due to wear likely from cold-starts. I ended up selling it to a fellow who was going to rebuild it.
Van Svenson thank you for getting back ,,, it was a wonderful video very interesting and detailed,,,so sorry for your loss,,,, that’s something I would love to do one day, a strip down and rebuild, ,,, what oil were you using at the time make and W number ,,,, , did you ever try a w10 40 to help with the noise ? Did you ever do an engine flush and injection cleaner to help get rid of the carbon buildup ,,, and did you ever invest in another Porsche,,,as you seem to have the ability to tackle anything cool with a Porsche engine... from your new subscriber RONEDEE best of luck out there.... thanks again for the super video....
is running BG44K or Techron frequently a way to prevent all of this crazy carbon build up? Can you over due it on a new 911 engine in order to prevent it from ever building up in the first place?
Fuel additives should help reducing carbon buildup in the combustion chamber. But I'd say the better solution is to avoid short run times (let everything come fully up to temp) and be liberal with high RPMs (once it's warmed up) - don't drive it like a granny.
I'm surprised you sold the engine. You had it out and broken down already. A trip to a machinist, new sleeves and pistons and the thing would be like new for a couple grand (if you know where to look). Everyone keeps quoting outrageous numbers that scored cylinder costs 15k, but that's if you go with a well known builder. If you can do the work yourself and a little research, no reason to spend more then 5-6k with many new parts. But just cylinders and pistons would be around 2-3 grand,assuming you have the tools and do the work yourself.
if one buys a brand new car, and from day one runs a quality fuel additive like Chevron Techron, CleanBoost MAXX, (or whatever you think is better)... will it keep the engine from getting this fouled up inside? Carbon built up etc?
I have no actual data to back this up, but I think the answer is no. I'm sure the additives will help, but the fact remains that gasoline is a hydrocarbon-based fuel that can only burn so clean. The explosion comes from the chemical reaction of the hydrogen and the carbon splitting (in the presence of oxygen) - much of that carbon will bond with the oxygen (making CO and CO2) during the process, but some carbon atoms remain unattached and/or bond with other carbon atoms.
My IMS BEARING collapsed and I bent ×6 exhaust valves I'm going to change front and back timming chains and ims bearing retrofit, pistons look fine I've decided not to split the case ,I really enjoyed your very informed videos and trust your experience please tell what should I beware of thank you
Van,
Thanks very much for the in-depth diagnostic of the M96 engine.With all the internet,publication editorial and various forums on the web about this particular Porsche engine we can see for ourselves what's happening here.Great piece of machinery and engineering by Porsche in light of the necessity to produce newer and more efficient designs that define what the iconic sports car is all about!
Trivia, Variocam was first introduced in the 1992 Porsche 968, a 240 NA I4.
Nice walk-through. Nice hardware. It looks to be made out of 100% unobtainum :O) at least for my pocketbook. Thanks for posting. Cheers.
Very interesting and clearly spoken. Thank you for the video
just fyi bore score starts at the bottom of cylinder 6, you really need to rotate piston 6 to bdc and/or look at the underside from the sump to confirm presence of bore score
Thanks for the greatly instructional video. I am thinking about buying a used Porsche so I am learning about their engines. I so like your slow pace and calm voice, the great amount of real content in your videos, a welcome change from all the hype and fluff of most UA-cam car videos.
On another note, do you have a recommendation for a good medium-duty engine hoist and engine stand? Thank you.
Hi Van did you get to the bottom of the knocking noise ?
Cylinder 6 is scored beneath the ring line, it's the piston skirt slapping the wall you can hear. Not the lifters, nothing to do with the heads, the reason the valves are carbonised up is there is oil being burned in the combustion chamber bypassing the oil control rings.
That's a great analysis!
the noise was probably piston slap . the skirts sure bad
Interesting. I was surprised to not see lifter trickery that allowed the valves to be opened more. I have a 968 head on the bench and its "VarioCam" includes this feature. I guess the big 6 cylinders don't need it! Very cool look inside the 996 engine nonetheless.
Great video!!
Thanks for the video!
It's not an injector problem. If the intake valves were loaded up it would be a different problem and possibly an injector. If the exhaust valves are loaded up it's because there's oil getting on the exhaust valve and or the valve isn't closing all the way because either the lifter is fully extended or the valves crashed into the piston. He needs to put the valve in a valve cutting lathe spin it and see if it's warped. If not put your lifters into advice and see if they're collapsible because one of those two is your problem. Now if the exhaust valves crashed into the piston you have to determine why only the number 6 exhaust valves crashed. It's not likely to be a warm timing chain in this case because you have two exhaust valves on number six that are crashed and no others and it would have been the intake valves that would have crashed if you had a warrant chain. So you're most likely cause his probably bad lifters because their clogged at number six. And just to be ultra clear when I say bad lifter I don't mean that they're collapsed I mean that they're fully extended and not draining.
Nice job. Hope you found another one.
amazing video, thank you for posting
Enjoyed this video....pity there was not some follow up videos going through fault finding and testing 👍🏻
What was the root cause to the issue with No.6 cylinder?
I think the cylinder scoring was due to excessively cold winter starts. I sold the car to a guy who planned on rebuilding it.
Great video. I am an engine idiot, but I am learning. This was a great info video
those valves are not burnt. That appears to be oil fouling from a leaking valve guide or piston rings. that would cause an incomplete burn, resulting in excess carbon fouling. there is the cause of your compression leak. your knocking noise is probably a clogged oil passage, or bad lifter. resulting in lose of oil pressure in the lifter, causing a tap. a tap that you are hearing as a knock.
Turns out the cylinder was scored up pretty bad - allowing oil to get past the rings.
Van Svenson That's harder to diagnose in a flat engine. The evidence is easily dissipated out through the exhaust. In a vertical or "V" paturn engine you would have noticed a heavy gasoline smell in the oil when drained.
repr26 n
Followed along with intrigue on these great videos, systematically deconstructing where the problem lay but did I miss a conclusion or solution ? Thx
I don't think I did a final video - but the cylinder was scored.
Van Svenson I have a 2003 911 Carrara with a scored cylinder, there is a loud piston slap noise.
Can the cylinder be resleeved?
a good clue is how the whole combustion chamber is extra clean.. like its been STEAM CLEANED..HELLO !! There is only one way it would be THAT clean....there was water entering the CC for sure Naturally coolant being burnt along with fuel in the combustion process isnt going to contribute to a quiet running engine..duh i would have to hear the noise before i called that one .. u better thank gawd u didnt have to put THAT engine back together...they sure come apart easy enough LOL
i agree with repr26 the valves were ok.. the oil is probably comin from stuck and/or clogged oil control rings
It was scored cylinder walls. It ended up becoming a project for someone else.
Typical issue for 3.6l 996, 295hp 3.4l Cayman S (pre-facelift), and 3.6/3.8l 997.1 engines. Hartech has made a lot of studying and the reason is most likely poor cooling of the 6th cylinder causing too much heat on it, so the oil looses its abilities to provide lubrication film causing metal to metal contact between cylinder and the rings/piston. There's no easy solution (double up the oil sprays and change head gasket with larger water passage hole for 6th one, which basically are only viable to do when rebuilding a failed engine), but apparently changing to a lower temperature thermostat can help prevent the issue. Doesn't help you, but anyone else there with those engines should seriously consider this.
Just a thought, as cylinder 6 had the classic bore scoring, all that carbonisation could be the oil entering the combustion chamber and due to incomplete combustion of th oil it fouled up the exhaust values on the exhaust stroke, compromising the seating? High oil consumption is one of many symptoms of scoring. My understanding is it’s a very localised coolant rate thing that causes hot spots on the thrust side of cyl 6, causing the bore oil to fatally thin, allowing the piston to fragment bits of the Nikosil liners off on the thrust side of cyl 6. It’s the fragments that then score the liner.
I really don’t like those open deck cylinders, they look so thin to my layman eyes :D
@@vsvenson interesting! Once you pulled the piston, was the bore visually bad? Did you get rid or have it rebuilt elsewhere? Keen to hear your thoughts and the outcome...
Cheers Russell
Impressive and interesting video
Great video.
Great video Van.
3.6 L...always wanted to one of these broken down. Interesting.
Hi Van, given the unfortunately diagnosis (i.e. bore scoring) and knowing the history & investment in this car, would you purchase another 996. If so, what would you do differently? Thanks for all the helpful videos!
I'd jump at a turbo or GT3, if I could afford it. :) Or, perhaps a southern 996 that didn't see cold weather.
RE: Cold weather 996 - is that because of the common issues surrounding driving in cold weather (i.e. salt/sand corrosion) or storage issues? Or, is this based on theories that claim people with cold weather 996 Porsches are more prone to common M96 problems like IMS failure, cracked heads, bore scoring, etc.??? Thank you for your time and advice! btw: I have a southern 996. Live near Jake Raby (Flat 6 innovations) for point of reference.
My car suffered from scored cylinders - presumably from the pistons heating up and expanding faster than the case on very cold startups.
The best 911 Porsche ever built
You are kidding 😳.....My 997 has more common faults with the same engine piston slap bore scoring etc...
what's the solution then??
How many miles did this engine run ? Lots of track ?
Thank you very interesting…great video
Hi! Thank you for the very detailed video! I have the same sound but I think it's on cylinder #4, were you ever able to determine what was the cause of the knocking? I'm wondering if I should fix this engine or just replace it. My guess was a rod bearing, but it isn't as loud as I remember hearing it on the inline 4 engine. And I couldn't find the follow-up video.
My issue was scored cylinder walls - likely from cold-weather starts
Carbon buildup on your exhaust valves is from shortshifting the car and not running cleaner through now and then...nothing looked cooked.
Maybe on a carbureted engine from 30 years ago.. and short shifting would put carbon on the intake too because of valve overlap.
Thank you for the video. Can you tell me how many solenoids are in the PORSCHE engine?
Thanks for your effort. Would like to hear and/or see how it went on. rgds tom
I ended up selling it to a guy who wanted to rebuild it.
You mentioned there are no bearings on the camshafts, could it be that the camshaft is wobbling a thiny bit which is just enough to change timing at the furthest cylinder? Just thinking loud here. Let us know the cause anyway.
P3t3rG1 The camshaft bearing surfaces look clean and smooth - if they were out of spec enough to cause that kind of noise, I'd expect to see visible scratching and wear. But keep the ideas coming!
Well explained video! I did a 3.6 teardown after an IMS failure. You can see this on my channel. Did you resolve the knocking problem?
I ended up selling the car to someone who wanted to rebuild the engine.
Next time maybe rotate the engine to show the bore score we all know is there is in cylinder 6. It’s 2024 if M96/M97 goes knock knock on number 6 you don’t even need to scope it, just pull it, strip and send it for nickies.
Valves not burnt to much oil around head cracked or liner problem water ingression inlet manifold crack ?
Scored cylinder walls.
So what was the out come of the noise in the end ,,, you didn’t do a part 3 video ????? I would of love to see more ,,,, thanks ...
The outcome was scored cylinder walls and piston slap - due to wear likely from cold-starts. I ended up selling it to a fellow who was going to rebuild it.
Van Svenson thank you for getting back ,,, it was a wonderful video very interesting and detailed,,,so sorry for your loss,,,, that’s something I would love to do one day, a strip down and rebuild, ,,, what oil were you using at the time make and W number ,,,, , did you ever try a w10 40 to help with the noise ? Did you ever do an engine flush and injection cleaner to help get rid of the carbon buildup ,,, and did you ever invest in another Porsche,,,as you seem to have the ability to tackle anything cool with a Porsche engine... from your new subscriber RONEDEE best of luck out there.... thanks again for the super video....
is running BG44K or Techron frequently a way to prevent all of this crazy carbon build up? Can you over due it on a new 911 engine in order to prevent it from ever building up in the first place?
Fuel additives should help reducing carbon buildup in the combustion chamber. But I'd say the better solution is to avoid short run times (let everything come fully up to temp) and be liberal with high RPMs (once it's warmed up) - don't drive it like a granny.
It all looks very expensive.
996 with 3,4L 300PS or 996 Facelift with 3,6L 320PS ?
Very nice Video!
It was the 3.4.
THX :)
Tubes only in 3.4
wow...you explain this amazingly well with a calming way. I learned a lot. Did you ever find out the problem on cylinder 6?
Yes, it was a badly scored cylinder. I ended up selling the car to someone who planned on rebuilding it.
Did this engine ever get fixed and put back together?
No - I ended up selling the car in as-is condition. The new owner planned to rebuild it.
was the bore scored?
Collapsed piston skirt causing knock and allowing excess oil past rings??
That's as good a theory as I have.
@@vsvenson i had that on a twin engine boat. Detonation in both number two cylinders caused collapsed skirt and scuffing
I was surprised to see an open deck block. Are the 997's open too?
I haven't had one open, so I don't know. But I think the general architecture is the same.
How many miles were on the engine
Only 60k. :(
Oh wow..
I'm surprised you sold the engine. You had it out and broken down already. A trip to a machinist, new sleeves and pistons and the thing would be like new for a couple grand (if you know where to look). Everyone keeps quoting outrageous numbers that scored cylinder costs 15k, but that's if you go with a well known builder. If you can do the work yourself and a little research, no reason to spend more then 5-6k with many new parts. But just cylinders and pistons would be around 2-3 grand,assuming you have the tools and do the work yourself.
Sometime I miss that car - you're right, I probably should have tackled it myself. But sometimes we don't always make the best decisions.
is it the 3.8L?
3.6
sir all engine timings mark setting 👆 thank you
if one buys a brand new car, and from day one runs a quality fuel additive like Chevron Techron, CleanBoost MAXX, (or whatever you think is better)... will it keep the engine from getting this fouled up inside? Carbon built up etc?
I have no actual data to back this up, but I think the answer is no. I'm sure the additives will help, but the fact remains that gasoline is a hydrocarbon-based fuel that can only burn so clean. The explosion comes from the chemical reaction of the hydrogen and the carbon splitting (in the presence of oxygen) - much of that carbon will bond with the oxygen (making CO and CO2) during the process, but some carbon atoms remain unattached and/or bond with other carbon atoms.
I build these Porsche Camshafts ^^
That's really cool!
For an American in 2019 you have a great vocabulary
all 996 and 997 will eventually suffer. scoring cylinders !! bad coating of walls an pistons by factory
electric car : no engine, no transmition....almost no high repair !
What a shame...never to run again...
T'is is the 991 engine
oh man engine's gone LS swap it like everything else in america
My IMS BEARING collapsed and I bent ×6 exhaust valves I'm going to change front and back timming chains and ims bearing retrofit, pistons look fine I've decided not to split the case ,I really enjoyed your very informed videos and trust your experience please tell what should I beware of thank you