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Rebuild advice needed after teardown
Ok, I tore my 80' SC 3.0L down today, and I was suprised at what I found. I expcted to find Aluisil cylinders, when in fact I found Mahle Niki's. The part number is 95ZN1W4, which I can't find anywhere. I'm guessing they are standard 95MM niki's for 3.0L, here are the pics:
![]() ![]() Now, I'm dropping these off at the machine shop to have them checked out for round and such. But, what should I do? Have them honed a bit and replace the pistons? Compression was down across the board, 120 ~130 and two cylinders with 35%+ leak trough the rings. It appears that the jugs were replaced, but not the pistons. What would you do? Next... I found that all of the lower studs are Dilivar according to Wayne's book. They are not magnetic, and they are of the correct color. The uppers are steel, and one of them pulled out: Do I do any replacement on this stuff? Other than the upper that pulled out? It's very clear to me that the engine has been gone through on at least one occasion, which direction so I go?
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2021 Model Y 2005 Cayenne Turbo 2012 Panamera 4S 1980 911 SC 1999 996 Cab |
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I think those need a re nichol job ( EBS ) not a hone. do they have a slight yellow hue to them ??
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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2021 Model Y 2005 Cayenne Turbo 2012 Panamera 4S 1980 911 SC 1999 996 Cab |
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3.4 Bigger is better
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Scott,
I would replace all the dilavar studs while you have them out with steel. The dilavars will break at some point. The 993 steel studs are around $10 each. I replaced the lower 12 when I did my rebuild, due to two broken dilavar studs. Cheap insurance! See how the measurements come out on the P & C's. Afterburn was talking about having the cylinders replated with Nakasil. If they are in spec you should just be able to clean the cylinder up with scotchbrite (do a search on scotchbrite in this forum, lots to read about nikasil cylinders) and re-ring the pistons. Are you looking at just rebuilding or are you looking for more HP?
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Michael 88 911 Diamond Blue CE Carrera 3.4 HC3.4 member 2020 Honda Passport Last edited by 88-diamondblue; 09-24-2006 at 09:25 PM.. |
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GAFB
Join Date: Dec 1999
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Interesting...never seen a stud pull out of an aluminum case before.
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EDIT: Forgot to mention four of the lowers three on one side and one on the drivers side are already steel studs. Looks like headstuds were the nature of the original repair.
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2021 Model Y 2005 Cayenne Turbo 2012 Panamera 4S 1980 911 SC 1999 996 Cab Last edited by Scott R; 09-25-2006 at 05:23 AM.. |
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You do not ever hone those, Like Diamond blue says ,a cyl rebuild is in order EBS might be a good choice ,all new studs will make you sleep better...............
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On to the lower end, what prompts a lower end rebuild on a 3.0L? I'm on the stand down to the case right now, I'm just worried that I'll never get the surface to reseal. Wayne's book makes it seem like it might be something I would mess up. The rods all seem great, bushings are within spec... What should I do?
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you are 2 hours away from a complete inspection.......it will open the way for more stuff...new chain and sprockets, crank polish, rod rebuild, rebalance....etc
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If your pistons are in spec, you could have the skirts coated and then re-plate the cylinders + match hone. This is as close to new as you will get with your oe P+C's. You could also put in JEs, but I don't think it's worth spending the extra money since the cylinders can't be opened up for 98s reliably with the sealing grooves. EBS Racing does this (as do I), or you could go with new P+C's in a 98mm bore and get some more displacement. There are lots of choices. Do a search.
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Charles Navarro President, LN Engineering and Bilt Racing Service http://www.LNengineering.com Home of Nickies, IMS Retrofit, and IMS Solution |
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Ben 89 944,85.5 944 914-6 2.4s GT tribute. 914-6werkshop.com |
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Yeah, I've done alusils as well. The only quesion there is ring compatibility with the re-ring on the original pistons on nikasil, but i'm sure it's been done.
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Charles Navarro President, LN Engineering and Bilt Racing Service http://www.LNengineering.com Home of Nickies, IMS Retrofit, and IMS Solution |
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What I am thinking of doing is replating my aluisil cylinders and buy JE pistons
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Ben 89 944,85.5 944 914-6 2.4s GT tribute. 914-6werkshop.com |
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That would work too. For what it's worth, as long as the original factory cylinders are in ok shape (not overheated or severly out of spec), they make great candidates for a re-plate.
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Charles Navarro President, LN Engineering and Bilt Racing Service http://www.LNengineering.com Home of Nickies, IMS Retrofit, and IMS Solution |
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For example, I won't replate a set of half-finned 97mm turbo cylinders, regardless of condition - they are a bad design to start with.
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Charles Navarro President, LN Engineering and Bilt Racing Service http://www.LNengineering.com Home of Nickies, IMS Retrofit, and IMS Solution |
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Thanks Charles, depending on what my mechanic says about the cylinders I may contact you for the plating.
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