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Join Date: Oct 2007
Posts: 249
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block is ruined
Just pulled the head off the engine that I have been rebuilding for the last 2 years to check on the cylinders before I torqued the head down and something must have fallen inside cylinder 2. The bores looked great and I gave them a final coat of oil then cranked the engine over a couple of times and now I have a huge groove in cylinder 2. It almost looks like something gouged the coating as there are two small bubbles like protrusions at the top of the gouge.
@ years of work down the drain in less than a minute. Not a good day! |
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09-08-2011, 11:50 AM
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Join Date: Mar 2008
Location: Chicagoland
Posts: 2,695
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ouch. what tolerance group is the block? if it's 0 or 1, still a change it could be rescued
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09-08-2011, 11:59 AM
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tolerance group 2
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09-08-2011, 12:05 PM
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 Picture of the damaged cylinder |
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09-08-2011, 12:16 PM
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Garage Helper
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Oh pfooey - Sorry to hear of your accident with the block. The Porsche 944 Motor is an Alusil Alloy block. It is one solid casting including the cylinder bores - there is not a coating or a cylinder liner there, just one block solid (Well except for oil and water passages, etc.). The process of re-boring and installing new cylinder sleeves is very expensive if that is necessary. The original cylinders can be bored slightly, but it may be that tolerance group 2 is as far as you could go...Any more over bore and the motor tends to over heat easily. Sorry to say but it may be time for a different block, as it is less expensive to re-condition a good used block than to repair yours...
It's a sad picture above...
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78-924 traded for 80-931 traded for 84-944 traded for 85.5-944 (7th one now).  UAV-M1 (Urban Assault Vehicle - Model 1) Bless the lowered, and pass the nitromethane. Pedal to the metal till you see the gates of hell then brake NLA - No longer available is a four letter word Last edited by Cocacolakidd; 09-08-2011 at 12:47 PM.. |
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09-08-2011, 12:45 PM
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Kind of what I figured. Just thought it was strange the way it looks.
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09-08-2011, 01:27 PM
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Garage Helper
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Not for sure but it looks like there was a burr or burrs on the ring gap ends - or that ring may be in there upside down, according to who made the rings. Could be that ring was broken also.
If those gouges are not to bad do you think they could polish out with Sunnen AN-30, a Alusil honing compound. What I mean about not to bad is will they catch a finger nail when dragged over the bad spot - Wishing you the best of luck
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78-924 traded for 80-931 traded for 84-944 traded for 85.5-944 (7th one now). UAV-M1 (Urban Assault Vehicle - Model 1) Bless the lowered, and pass the nitromethane. Pedal to the metal till you see the gates of hell then brake NLA - No longer available is a four letter word |
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09-08-2011, 03:36 PM
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The engine had been turned over numerous times before today and no damage to the cylinder. The only thing I can think of is that something got between the top ring and the cylinder. I was going to try and get some AN-30 and hone it out as i can't make it any worse at this point. Going to pull the pan off next week and pull the pistons out. Cant wait to see what caused it.
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09-08-2011, 04:57 PM
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Join Date: Jun 2005
Location: backwoods, alabama
Posts: 331
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did you have the pistons out? looks like the end of one of the rings are out of the groove.
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86' 951 k26/27 hybrid turbo 01' audi s4 98' TDI jetta 96' 933tt AWD LS1 |
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09-08-2011, 05:26 PM
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No, I had assembled the engine and coated the cylinder walls with oil. I then turned the engine over about 6 times and checked the cylinder walls and everything looked good. Put the head to protect the cylinders as I new the engine would be sitting for a few months. Pulled the head off today and checked the cylinders and all looked good. Put a light coat of oil on the cylinder walls and then cranked the engine over once and noticed the damage. The damage has to have been caused by the top ring because of where it stops in the bore. Just can't figure out what caused it and what caused the bubbling affect on the top. Almost looks like something dug into the metal but the engine turned over really easy.
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09-08-2011, 05:54 PM
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Garage Helper
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Let us know what happened - very interesting...
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78-924 traded for 80-931 traded for 84-944 traded for 85.5-944 (7th one now). UAV-M1 (Urban Assault Vehicle - Model 1) Bless the lowered, and pass the nitromethane. Pedal to the metal till you see the gates of hell then brake NLA - No longer available is a four letter word |
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09-08-2011, 05:58 PM
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Anyone know where I can buy some sunken an-30?
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09-08-2011, 06:30 PM
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I hate auto correct! Sunnen an-30
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09-08-2011, 06:31 PM
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Garage Helper
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__________________
78-924 traded for 80-931 traded for 84-944 traded for 85.5-944 (7th one now). UAV-M1 (Urban Assault Vehicle - Model 1) Bless the lowered, and pass the nitromethane. Pedal to the metal till you see the gates of hell then brake NLA - No longer available is a four letter word |
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09-08-2011, 08:00 PM
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Architect / Car Guy
Join Date: Jan 2009
Location: Atlanta, Ga
Posts: 699
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how does it run?
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Looking Forward to getting my First "car" Porsche 951 |
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09-09-2011, 05:55 AM
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Toofah King Bad
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Bummer. . .hard to believe that much damage from turning the engine by hand.
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» 1987 924S Turbo - Got Boost? « "DETERMINATION. Sometimes cars test us to make sure we're worthy. Fix it." - alfadoc |
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09-09-2011, 06:23 AM
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I had a similar issue when I rebuilt my 928,(but I caught it) When I installed my pistons the rings actually shaved slivers off the piston ring compressor tool that wedged between the ring and piston. I had one fine scratch but I imagin continued rotation of the motor may have resulted in something similar
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1979 928 85 Euro 2v motor,S4 Brakes and suspension, 1988 951 street legal track car(sold) Neon SRT4 track car |
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09-09-2011, 06:43 AM
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Eureka912
Join Date: Aug 2010
Location: Northcoast of California in Eureka
Posts: 115
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Those 'bubbles' look to stand proud of the cylinder wall. It almost looks as though you have uncovered some porosity in the casting as opposed to a 'groove' from a mechanical source.
Just a possibility I did not see mentioned in the thread.....just sayin' dws
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1966 Porsche 912-1966 Studebaker Commander V8 1981 Mercedes 380SL-1984 Porsche 944 1986 Jaguar XJ-S V12-1986 Corvette C4 Z51 2007 Audi A4 Quattro Cabriolet(wife's ride) 2010 BMW 328i/M Sport(my daily) |
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09-09-2011, 07:52 AM
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I am going to pull the piston out over the weekend and hopefully will have some answers in a couple of days
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09-09-2011, 08:09 AM
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Banned
Join Date: Apr 2011
Posts: 683
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I'd just try running the ****er once to see before you throw it all away
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09-09-2011, 08:37 AM
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ORACLE
Shaggy
Red
Chumpy
Weiße Scheiße
1988 Porsche 951
