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Stumble, Rumble, Hard-to-Start

Received the DIY Enema Kit today, time to get a look at those pistons.



[Image: borescope.jpg]
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Borescopes are great. The one I have is too big for the spark plug hole. If yours works good, please post a link where you bought it. Looking forward to pictures. The trick will be if you can see the valves. The top to the piston just isn't that interesting. <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" />
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Well, I can see the pistons well enough to see a large hole in the number 2 piston, and large chunks missing from the edge of the number 4 piston. <img src="/forum/images/smilies/968/ninja.gif" class="smilie" alt="" /> Big fat j/k there, but when I first put the borescope through the hole and it was still fuzzy, the deposits on top of the pistons looked exactly (to my untrained eye) like the aforementioned catastrophes. <img src="/forum/images/smilies/968/ninja.gif" class="smilie" alt="" />



Thank the Good Lord that it was oily black deposits, but now I need to figure out what the schmoo is on the pistons. The plugs are dry and look fine (albeit they are relatively new), and I want to ensure at all costs there is no damage from silent pre-ignition that would look like this:



[Image: Piston-Detonation-Lrg.jpg]
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Borescope is only 7mm, fits easily into the cylinder, and is very flexible. Took a lot of pics of the pistons so far, and I may work on bending it to get it to view the valves.



I got it on Amazon and it came in less than a week from Hong Kong. The software with it is pretty good - it measures angles, circles, distances, etc., and takes pictures and videos.



http://www.amazon.co...0?ie=UTF8&psc=1



Edit: I have a bunch of pictures of the pistons, but the forum software makes it too hard to include them, so screw it for now. Maybe later. This "bundling of replies" messes things up - you can add a bunch of photos, then if you have to edit the post, it tells you that you now have too many.
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Second crack at posting the photos.



[Image: piston_1.jpg]

[Image: piston_2.jpg]

[Image: piston_3.jpg]

[Image: piston_4.jpg]

[Image: piston_5.jpg]

[Image: piston_6.jpg]

[Image: piston_7.jpg]

[Image: piston_8.jpg]

[Image: piston_9.jpg]

[Image: piston_10.jpg]
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lots of oil in there. i'd be looking at your guides.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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[Image: piston_11.jpg]

[Image: piston_12.jpg]

[Image: piston_13.jpg]

[Image: piston_14.jpg]

[Image: piston_15.jpg]

[Image: piston_16.jpg]

[Image: piston_17.jpg]

[Image: piston_18.jpg]

[Image: piston_19.jpg]

[Image: piston_20.jpg]
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[Image: piston_21.jpg]

[Image: piston_22.jpg]

[Image: piston_23.jpg]
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Agreed, that's a lot of oil. My first theory though is the air oil separator, which was leaking pretty good.
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i doubt it, but it's worth checking.



besides the obvious, the issue now is that you have raised the compression ratio with that oil film on top. you would be amazed at how much of a difference that makes. you need to get that oil out of there. there are a few products out there to do that. it will require a couple of oil changes though.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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I figure it's best to check the easy stuff first, rather than assume it's the worst case. One reason I want to rule out the AOS is the article at https://sites.google...atorreplacement, which includes:





"The AOS is intended to reduce the pressure in the crankcase in an acceptable way by allowing some pressure created by piston ring blow-by to be vented into the engine air intake for disposal through the normal combustion process. When there is a hole IN the AOS, the airflow increases and more oil is sucked out of the crankcase in amounts that overwhelm the AOS's ability to separate the air/vapors from the oil droplets. The result is more oil through the AOS into the air intake, through the throttle body and into the combustion chambers. Of course while this is going on the Mass Air Flow Sensor (<acronym title='mass air flow'>MAF</acronym>) is totally confused because there is a source of air that is entering the airstream after the <acronym title='mass air flow'>MAF</acronym> has measured the airflow so the ECU (computer that controls the air-fuel mixture) is now totally confused. The result is a bad running engine."



... and ...



"One possible clue is to try and remove the oil fill cap while the engine is running. If the AOS is normal, you should be able to easily remove the cap. If the AOS is failing, the cap will be under very noticeable vacuum and harder to remove."



... and ...



"After checking all connections and inspecting the engine bay area I notice a "misty" build up on several areas surrounding the oil separator. Upon thorough inspection of the oil separator I could not find a leak or loose connection anywhere."



While I don't have oil sludge in the throttle body, my oil cap is pretty much impossible to remove with the engine running, but easy to remove with it off. I also have that oil misting all over the side of the engine, especially at or near the bottom connection of the AOS, which I thought was suspect when I was taking it off. I could see much of the green o-ring around the nipple, even when it was still fully installed in the engine, which I thought was odd. Usually you can't see much of an o-ring when it's fully seated.



I agree I have to get that oil out of there - I'm wondering what to do about that and all I can come up with is solvents and oil changes... I don't have excessive oil consumption, I've only added a couple of quarts in 10,000 miles, and I've never seen or heard of blue smoke coming out of the tail pipe, so it's yet another mystery to tackle one step at a time.
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[quote name='flash' timestamp='1377566139' post='148094']



besides the obvious, the issue now is that you have raised the compression ratio with that oil film on top. you would be amazed at how much of a difference that makes.

[/quote]

All agree the oil source has to be found, but I don't see the math that supports a raised compression problem. A cooked oil coating 0f 0.005" (which I think is unimaginably thick) would only raise the CR by 0.15. A still quite thick 0.001" would raise it by 0.03.
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he has more than that in there. i've seen oil coatings of nearly .030" a basic carbon coating from use will raise the compression about 2 tenths. i've seen oil coatings raise it a full half point. remember that even 1 tenth is a lot when you are talking about forced induction.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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Are you guys talking about the carbon that results from burned oil. I'm not sure I understand how oil can live as oil in a combustion chamber for any length of time other than starting and stopping the engine. Is it's flash point that high?
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lol - you should have seen how much was in my cylinders when we pulled the motor apart. it was a good slimey coating, probably about .030" thick. nasty stuff. had to scoop it off the pistons. i'd guess about 2 teaspoons full each. engine still ran well. it just smoked like a freight train.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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This oil is surprisingly liquid and thick.
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Two weeks and still waiting for o-rings from Auto Atlanta...
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this is why i never do business with them. any savings is long lost in hassle. also, their stock is "old new stock", which is stock that has gone past its shelf life according to porsche.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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Actually, that would be the "Home Colonoscopy Kit" not the home enema kit as nothing but the camera is inserted - lol....
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Just remember if you see the light in the back of your eyes you've gone too far <img src="/forum/images/smilies/968/blink.png" class="smilie" alt="" />
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