Cylinder wall cracking thought...
#17
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Originally Posted by Tippy
Magnesium nor aluminum would hold up to the heat and stress of a cylinder. It has to be steel, cast iron, or chromium lined (like aircraft cylinders) which I do not know what Porsche uses. Every aluminum engine I know of uses a disimilar metal sleeve and I have never heard of a reaction of the two causing issues, I believe there is more to it like, fits and clearances. Although I dont claim to be an expert, just my knowledge of engines over the years.
#18
Race Car
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Originally Posted by Russ Murphy
That's just plain wrong. Every Porsche I've owned has had aluminum cylinders.
#19
Race Car
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Originally Posted by Tippy
You are wrong, you have to have some kind of coating (nikasil, chrome) or the alunminum of the piston and the aluminum of the cylinder would gall, not to mention the steel rings on the pistons would tear the aluminum cylinders instantly. Not to mention forged pistons are a harder aluminum than the aluminum of the cylinder. The piston would seize in the bore without a hard coating over the aluminum.
#20
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Originally Posted by Tippy
You are wrong, you have to have some kind of coating (nikasil, chrome) or the alunminum of the piston and the aluminum of the cylinder would gall, not to mention the steel rings on the pistons would tear the aluminum cylinders instantly. Not to mention forged pistons are a harder aluminum than the aluminum of the cylinder. The piston would seize in the bore without a hard coating over the aluminum.
#21
Race Car
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Originally Posted by Russ Murphy
How about Aluminum and silica? Alusil. 951 motors. And in your post it appeared to me you were stating that aluminum cylinders wouldn't hold up without a sleeve or chromium plating. Saying that a nikasil coated cylinder isn't aluminum is silly. Kinda like saying your wheels aren't aluminum because they're anodized to protect the finish.
Aluminum cylinders would not hold up. You cannot claim that your cylinders are aluminum when it is sleeved or coated with another material. The cylinder is the inside of the bore and since it is sleeved or coated, the cylinder is not aluminum. The block may be aluminum, but not the cylinders.
Is a wooden baseball bat that is corked, a wooden bat or cork?
#22
Burning Brakes
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Originally Posted by 99firehawk
99/100 TIMES INTER MIX IS A BAD OIL COOLER, IVE NEVER SEEN OR HEAD OF THE PROBLEMS YOUR DESCRIBING. DO SOME RESEARCH BEFORE YOU CASUE PANDEMONEM OVER AN IMPORPER DIAGNOSIS ON A ONE TIME SITUATION
EVERY 996 IS NOT A TIME BOMB
EVERY 996 IS NOT A TIME BOMB
#23
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inermix is a docmented problem. Headgasket failure, oil cooler failure and sleve failure. im yet to take one apart that had broken down passage ways or material from block break down in the the coolant or oil. 18k is too much, engine is about 9k + labor 2-3k
#25
Race Car
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Originally Posted by Russ Murphy
So that round thing that sticks up from the bottom of the block isn't a cylinder?
The pistons do not touch any aluminum, regardless of what you want to call the material that makes up a cylinder. If you want to be percise, the piston touches nothing in a properly setup engine.
Aluminum with Silicon, is no longer aluminum. Aluminum to aluminum pistons to cylinder would not last long before the engine seized up.
Last edited by 1999Porsche911; 10-10-2006 at 05:15 PM.
#26
Race Car
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Okay, I dont want to get into a pissing match, but those pictures do not prove anything. Where the carbon build-up is (very top of cylinder) would show if the cylinder is lined or not. Let me back up, I am a aircraft mechanic and the horizontally opposed motors of aircraft are of very similar design of the air-cooled 911 variants. YES, the cast cylinder is made of ALUMINUM, but the inside lining is of thousandths thick chromium in SOME but not all engines. They first plate the bore of the ALUMINUM cylinder with chromium, then they reverse the polarity and the chromium cracks, leaving a nice crosshatch for oil to cling to. If you had the cylinder completely cleaned to a shine, I believe you would see a parting line, showing where the aluminum ends and the plating of whatever material (nikasil, steel) begins. If that cylinder does not have some type of coating to protect the ALUMINUM, I will not know what to say other than I was wrong, I apologize, and you learn something everyday.
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#27
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Well, my cylinder #1 intermixed the coolant with the oil - WHEN THE CYLINDER CRACKED IN 2 PLACES. Instead of guessing what the problem was and buying a new motor, I paid a guy to tear the motor apart so I could see EXACTLY what went wrong. At first we figured it was a slipped cylinder lining (as they cannot be aluminum as posted above), but that did not turn out to be the case.
Newport 996 - how did you get PCNA to replace the motor at 74K under warranty? Was it CPO'd? Are you the original owner? They told me to pound sand when mine had only 52K miles.
Newport 996 - how did you get PCNA to replace the motor at 74K under warranty? Was it CPO'd? Are you the original owner? They told me to pound sand when mine had only 52K miles.
#28
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hard to tell what the casue of failure was after the fact, if the head gasket fails it will flood the cyinder and hydro lock usually destroying the piston or the cylinder wall or valves or rings ro all of the above
#29
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Hi I have a 2001 c4 cab which has recently suffered from a cracked cylinder 1. Porsche really screwed up with these engines! does anyone know whats the cheapest fix for this? and how much it would cost?
#30
Three Wheelin'
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A used engine is the cheapest route and will cost between 6-10k.
Tearing the engine down and having the cylinders fixed will cost minimum 6/7k DIY (4k alone for the larger bore), assuming that is the only problem... having a shop do it will be in the 15-20k range.
Used engines
http://www.flat6innovations.com/shop/home.php?cat=394
Sleeving
http://www.lnengineering.com/boxster.html
"In either situation, we can upgrade your engine to use our Nickies™ as long as there are no cracks in the case that protrude deeper than the bottom of the water jacket, where in that case, the integrity of the whole crankcase has been compromised! (see below). If the damage on the crankcase side, the damage is not repairable."
Tearing the engine down and having the cylinders fixed will cost minimum 6/7k DIY (4k alone for the larger bore), assuming that is the only problem... having a shop do it will be in the 15-20k range.
Used engines
http://www.flat6innovations.com/shop/home.php?cat=394
Sleeving
http://www.lnengineering.com/boxster.html
"In either situation, we can upgrade your engine to use our Nickies™ as long as there are no cracks in the case that protrude deeper than the bottom of the water jacket, where in that case, the integrity of the whole crankcase has been compromised! (see below). If the damage on the crankcase side, the damage is not repairable."