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Old 05-04-2017, 05:34 PM
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996 Neunelfer
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Default Intro and Dismay...

I've been meaning to post an introduction on the forum since purchasing my first p-car; an Atlas Gray 2004 911 C2. Car had basic options; Bose stereo, heated/power seats, and 18" wheels. Simple, just the way I wanted.

Since experiencing some issues with the car since the purchase I thought I'd kill two birds with this thread...

The Good:
Purchased the the car in October 2016 with ~72k on the clock. The car was a two owner vehicle, with the 2nd owner putting the vast majority of miles on it (50k+). The car had a binder full of service records since new. Oil was changed every 3-5k miles. IMS was proactively done by the 2nd owner upon purchase. Coolant tank and water pump had also been proactively replaced. Anything possibly wrong with this car the prior owner had it promptly taken care of. It appears the car had been tracked a few times (track pad swap service in the records) but there were no Type 2 over revs present. Overall the car was in darn good shape compared to others I looked at and the PPI report had no major revelations. I decided I would take the plunge and buy it for $24k. Funny enough I purchased the car 2 weeks after my wedding. I was more nervous buying my first Porsche than I was getting married... go figure!

The Bad:
The car has consumed oil since purchase. I've personally only put about 1,300 miles on the car. The dealer I purchased from changed the oil with Mobile 1 0W-40, so I thought it best to swap with a better quality 5W-40 to improve consumption. Went with Joe Gibbs DT40. Car was still going through oil faster than the 600 miles/qt. I've seen cited on the forums as "normal". I didn't put a ton of miles on the car after the oil change as I put the car away for the winter. Now that it's back out for the spring I have been able to gather some better consumption data. I'm going through a quart of DT40 in ~200 miles. Drive side tail pipe is BLACK. There was often puffs of blue smoke out of that tail pipe at startup. Per that recent Jake Raby post on BAT, I started using LiquiMoly Jectron in the tank which helped with the blue smoke, but not consumption. All signs point to scored cylinder on bank 2 unless I missed something searching these forums. Time will tell...

Car was driving perfectly fine other than the oil consumption. Pulls hard, engine sounds pretty quiet to me, and runs smooth. On a recent drive I had the check engine light come on (P2098 - Post Catalyst Fuel Trim System Too Lean bank 2). Thinking that the oil burning is finally doing in my cats or O2 sensors (or both). Still drove fine getting back home, but I'm not driving it anymore until it's checked out.

Living in Southern CT, I have a few highly regarded Indy's within driving distance, so I'm going to give Daniel Jacob's a call and hopefully drop the car off this weekend. Pretty devastated that my foray into P-cars has had such a rough start, especially after doing all the research to find the "right" car. Trying to determine the costs to fix a scored bore makes me a bit ill...
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Old 05-04-2017, 05:44 PM
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5CHN3LL
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The oil consumption could also be a less costly issue, like a failed AOS and the resulting intake coated with oil mist...

There is no shortage of "just buy a case of oil and keep it in the back seat" opinion on the Interweb, but that's a LOT of oil to be pushing through the engine...eventually, the cat for the dirty side is going to fail, which would still be better than hydrolocking after an especially big gulp of pooled oil. I think you're doing the smart thing...this sure feels like one of those issues where the estimated repair costs will grow in a nonlinear fashion. I'm imagining a parabolic curve with the arrow pointing toward the big end of the $$$ scale...

Here's to hoping it's a fix that requires no commas.
Old 05-04-2017, 05:46 PM
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808Bill
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Welcome to the madness...
Old 05-04-2017, 05:47 PM
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Always wanted 1
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I'm sorry to hear about the oil consumption. The car looks great, though. I just took the plunge into my first Porsche last week and reading things here terrifies me...
Old 05-04-2017, 06:02 PM
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996 Neunelfer
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Originally Posted by 5CHN3LL
The oil consumption could also be a less costly issue, like a failed AOS and the resulting intake coated with oil mist...

There is no shortage of "just buy a case of oil and keep it in the back seat" opinion on the Interweb, but that's a LOT of oil to be pushing through the engine...eventually, the cat for the dirty side is going to fail, which would still be better than hydrolocking after an especially big gulp of pooled oil. I think you're doing the smart thing...this sure feels like one of those issues where the estimated repair costs will grow in a nonlinear fashion. I'm imagining a parabolic curve with the arrow pointing toward the big end of the $$$ scale...

Here's to hoping it's a fix that requires no commas.
I've been hoping (dreaming) that it can all be traced back to an AOS. I don't have any vacuum data, but removing the oil filler cap does not cause the car to stall - idle gets a tad rougher - but it won't stall. Also, the single exhaust being dirty is really the damning part in my head. I'd expect an AOS to cause both pipes to be equally dirty. We shall see...
Old 05-04-2017, 06:03 PM
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I agree with CHN3LL. Don't assume it is a scored bore, or other very costly failure, resulting in high oil consumption. You may have a bad AOS and fouled one O2 sensor before the other side fouled. You do need to get it addressed though. Non-functional O2 sensors will cause all sorts of problems (based on my experience with other non-Porsche vehicles). I am sure the experts on this forum can tell you more. I hope it turns out to be a relatively inexpensive fix. I just purchased my 911 a couple of months ago. There seems to be a lot of posters on this site that are truly concerned about the longevity on their M96/M97 engines. I have to admit that the more I learn, the more concerned I am about my 99 996 with its original engine. I believe it has the original IMS bearing and possibly the original RMS. My car was tracked for the first 42,000 miles of its life, with a roll cage and all, but it runs great.

I re-read your post and see that one side of the exhaust is sootier than the other. That is a little more concerning.
Old 05-04-2017, 06:07 PM
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As I have learned recently, the scored cyl issue can't always(or often?) be seen with a simple borescope exam through the plug well. Apparently the damage is often further down in the swept area of the piston. So, the alternative is to drain the oil through a white rag, look for particles of metal. Then remove the sump plate and inspect the bores from the inside with the piston near the top of the throw(or partway up). This is a couple hour job, but any decent Porsche Indy mech should be able to perform it. Also, you get to look at your chain guides, and check for metal swarf with the sump plate off.
Old 05-04-2017, 06:27 PM
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996 Neunelfer
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Originally Posted by docmirror
As I have learned recently, the scored cyl issue can't always(or often?) be seen with a simple borescope exam through the plug well. Apparently the damage is often further down in the swept area of the piston. So, the alternative is to drain the oil through a white rag, look for particles of metal. Then remove the sump plate and inspect the bores from the inside with the piston near the top of the throw(or partway up). This is a couple hour job, but any decent Porsche Indy mech should be able to perform it. Also, you get to look at your chain guides, and check for metal swarf with the sump plate off.
I've been wondering that but couldn't find any definitive answers. That would certainly add some complications (i.e. $$$) to the diagnostic process..

I have been debating between Speed Sport Tuning (they did Ammo NYC's 964) and Daniel Jacob's to take the car. Both have excellent reviews, but know some people personally who have used Dan Jacob's.
Old 05-04-2017, 06:36 PM
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OP sorry to hear about your issues, keep as all posted. There is a very strong 996 brains trust on here that can help advise post diagnosis.

Originally Posted by docmirror
As I have learned recently, the scored cyl issue can't always(or often?) be seen with a simple borescope exam through the plug well. Apparently the damage is often further down in the swept area of the piston. So, the alternative is to drain the oil through a white rag, look for particles of metal. Then remove the sump plate and inspect the bores from the inside with the piston near the top of the throw(or partway up). This is a couple hour job, but any decent Porsche Indy mech should be able to perform it. Also, you get to look at your chain guides, and check for metal swarf with the sump plate off.
Draining the oil through a sive is what my OPC does when they service my car but they use pantyhose!
Old 05-04-2017, 06:44 PM
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I admit that it's been at LEAST a month since I've been elbow deep in the engine bay, and my urge to get in far enough to see how the AOS connects to the intake is VERY limited, but I don't recall the AOS's connection to the T being dead-nuts in the center. If it's offset one way or the other, or if the intake is canted to one side or the other, any oil that has pooled will drain to the lowest point...

Sure, probably fantasy, but here's to hoping there exists a less expensive explanation for why one side is sootier than the other.
Old 05-04-2017, 06:48 PM
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Both 0w-40 and 5w-40 oils have the same viscosity at high temps.

You won't cure an oil consumption problem by a change of oil. Be aware if you drive in cold temps -- -25C or colder -- Porsche says 0w-40 should be used.

The behavior of the engine with the oil filler tube cap removed is normal.

With no smoking or other signs of any problems the high oil consumption is probably due to a lousy -- but not failed -- AOS.

However, I would not could not recommend a premature AOS replacement.

My advice would be then to just live with the condition. Carry a quart or two of oil in the front trunk -- I use a larger plastic tub so if the bottle leaks it doesn't get oil all over the trunk carpets, etc. -- and add oil when the level gets low enough to take a quart of oil. Should be every couple of tanks of fuel.

Be sure you don't over fill the engine with oil. The oil level should be no higher than the max bar when you check the oil level with car on level ground and the engine/oil up to operating temperature.

At some point the AOS will go bad and then you will have to replace it and hopefully as a bonus find the oil consumption has gone down.
Old 05-04-2017, 06:50 PM
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Originally Posted by Always wanted 1
I'm sorry to hear about the oil consumption. The car looks great, though. I just took the plunge into my first Porsche last week and reading things here terrifies me...
Run away now and never look back!
Old 05-04-2017, 06:55 PM
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5CHN3LL
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The third option is to use a $40 Amazon manometer to verify the crankcase vacuum so you are not guessing whether the AOS is bad and you're not pouring quarts of oil into your cats (and subsequently the sky). See Ashai's DIY. Then proceed because you'll KNOW whether it's good or bad.

Originally Posted by Macster

With no smoking or other signs of any problems the high oil consumption is probably due to a lousy -- but not failed -- AOS
Did you actually read the post before firing up the TomeMaster 5000? At least one O2 sensor is probably shot (or an upstream cat is on the way out), and one tailpipe is obviously burning more oil than the other per OP's OP. Up there. ^^.
Old 05-04-2017, 07:12 PM
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996 Neunelfer
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Originally Posted by Macster
Both 0w-40 and 5w-40 oils have the same viscosity at high temps.

You won't cure an oil consumption problem by a change of oil. Be aware if you drive in cold temps -- -25C or colder -- Porsche says 0w-40 should be used.

The behavior of the engine with the oil filler tube cap removed is normal.

With no smoking or other signs of any problems the high oil consumption is probably due to a lousy -- but not failed -- AOS.

However, I would not could not recommend a premature AOS replacement.

My advice would be then to just live with the condition. Carry a quart or two of oil in the front trunk -- I use a larger plastic tub so if the bottle leaks it doesn't get oil all over the trunk carpets, etc. -- and add oil when the level gets low enough to take a quart of oil. Should be every couple of tanks of fuel.

Be sure you don't over fill the engine with oil. The oil level should be no higher than the max bar when you check the oil level with car on level ground and the engine/oil up to operating temperature.

At some point the AOS will go bad and then you will have to replace it and hopefully as a bonus find the oil consumption has gone down.
Can a "lousy" AOS cause that much oil consumption? Living with it and I'd be adding a quart and half every tank of fuel. Plus my sanity would probably go waiting for something else bad to happen. In the short term I have just been doing my best to keep the oil topped off. Also, curious, why would you not recommend a premature AOS replacement if it's on the way out?
Old 05-04-2017, 07:17 PM
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996 Neunelfer
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5CHN3LL - can you link the DIY? Is this the one where you need to buy an oil filler cap and modify it with a fitting for the digital manometer? Thought about purchasing one to check it out, but the symptoms don't seem to fit AOS exactly. I'm sure it needs to be replaced at this point and it's not helping the situation, but I'm not sure it's the entire cause of the issue. I couldn't see oil in the intake favoring a bank of the cylinders.

P.S. thank you for the all the replies everyone, awesome forum!


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