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YOUR RESEARCHSave $100 bucks on head bolts if you want to
Leading reported evidence
Use arp carrier bolts in my build
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Recommend buying new factory bolts as they don't fail
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Suggestion
For the carrier bolts, when I was building my engine, the ARP bolts were hard to find and people recommended buying new factory bolts as they don't fail.
Leading evidence: 'Use arp carrier bolts in my build' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Recommend buying new factory bolts as they don't fail' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
Very early M96 engines up to year 97 used M10 X 234mm "Torque to Yield" bolts, but were changed in 98 to M10 x 230 "non-Torque to Yield" bolts, and can be re-used.
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Performed · outcome unconfirmed · Original poster
The "torque to angle" procedure can be used on both "torque to yield bolts' and "non-torque to yield bolts'.
Recommend buying new factory bolts as they don't fail
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Suggestion
For the carrier bolts, when I was building my engine, the ARP bolts were hard to find and people recommended buying new factory bolts as they don't fail.
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Suggestion
Are those re-usable or replaced according to the Porsche book?
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Recommend buying new factory bolts as they don't fail
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Suggestion
For the carrier bolts, when I was building my engine, the ARP bolts were hard to find and people recommended buying new factory bolts as they don't fail.
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Suggestion · Original poster
You may find it interesting that the Porsche shop manual will specifically tell you to replace numerous certain bolts, will even be so detailed as to tell you to replace o-rings, gaskets, even to the point it sounds like they are instruction 5 year olds on how assemble engines, but no where will it say to " replace head bolts"..or " install new head bolts".
Replace numerous certain bolts, will even be so detailed as
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Suggestion · Original poster
You may find it interesting that the Porsche shop manual will specifically tell you to replace numerous certain bolts, will even be so detailed as to tell you to replace o-rings, gaskets, even to the point it sounds like they are instruction 5 year olds on how assemble engines, but no where will it say to " replace head bolts"..or " install new head bolts".
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Suggestion · Original poster
You may find it interesting that the Porsche shop manual will specifically tell you to replace numerous certain bolts, will even be so detailed as to tell you to replace o-rings, gaskets, even to the point it sounds like they are instruction 5 year olds on how assemble engines, but no where will it say to " replace head bolts"..or " install new head bolts".
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Suggestion · Original poster
The "torque to angle" procedure is just a more accurate way of tightening a fastener than just "torque to spec" procedure because it reduces the effect of variable friction of the threads and bolt head or lube.
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Suggestion · Original poster
So, it was quite a shock when I saw the "can be re-used" pertaining to the head bolts, normally it is assumed if it doesn't say to replace, then they can be re-used, but this is the only instance where I have seen the "can be re-used" printed and not just assumed.
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Suggestion · Original poster
So, it was quite a shock when I saw the "can be re-used" pertaining to the head bolts, normally it is assumed if it doesn't say to replace, then they can be re-used, but this is the only instance where I have seen the "can be re-used" printed and not just assumed.
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I have known that the head bolts on M96 engines were not Torque To Yield Bolts, as an experienced Technician can actually feel the bolts yield as the torque /angle procedure nears the end. The M96 head bolts do not yield.
The "torque to angle" procedure is just a more accurate way of tightening a fastener than just "torque to spec" procedure because it reduces the effect of variable friction of the threads and bolt head or lube.
The "torque to angle" procedure can be used on both "torque to yield bolts' and "non-torque to yield bolts'. The difference is in the bolt material itself and the point at where it yields.
Very early M96 engines up to year 97 used M10 X 234mm "Torque to Yield" bolts, but were changed in 98 to M10 x 230 "non-Torque to Yield" bolts, and can be re-used.
You may find it interesting that the Porsche shop manual will specifically tell you to replace numerous certain bolts, will even be so detailed as to tell you to replace o-rings, gaskets, even to the point it sounds like they are instruction 5 year olds on how assemble engines, but no where will it say to " replace head bolts"..or " install new head bolts".
So, it was quite a shock when I saw the "can be re-used" pertaining to the head bolts, normally it is assumed if it doesn't say to replace, then they can be re-used, but this is the only instance where I have seen the "can be re-used" printed and not just assumed.
This is FYI only, so use the info to save $100, or not...BTW I have never seen a head bolt failure on the M96.( I can't say that about many engines)..
Part #20 head bolt
(#20) M10 x 234 and #20 M10 x 230
It's not surprising to me since there is an industry wide confusion on the topic, and the widespread misconception that if torque-to-angle method of tightening is used, it means it is a "torque-to-yield bolt" and must be replaced.
The manufacture is the only one who knows the metallurgy of the bolts and whether or not they are TTY bolts or non-TTY bolts and can be re-used. They are not marked "TTY" on the bolt head like ARP bolts are marked with ARP ARP for the standard 8740 bolts, and ARP 2000, ARP L19, ARP 625+ ect for their specific metallurgy properties.
But it is definitive here that the very early M10 X 234mm are TTY and should not be re-used, but the M10 X 230mm are not TTY and can be re-used. If in doubt, a simple measurement of the bolt length will confirm. A 4mm difference will be easy to tell.
Thanks for the info. This sure would have saved me almost $500 if I knew this the first time I had the heads off. Why $500? Each bolt is $10 and there are 24 of them......times this by two since I pulled the heads twice. That's a lot of unnecessary paperweight I have now.
WOW !! The price has gone way up, I remember when they were $4 bucks each, but I also remember when a complete "plug and play" reman M96 engine was 7k also. Maybe I need to correct the title to say "save $250"..
Resurrecting an old thread here. Has anything come out since this thread stating that head bolts can't be reused on a 2004 engine? If they can't be reused, are the Elring head bolts equal quality to the Porsche bolts?
You can re-use the head bolts in your 2004 M96 if you want to, Porsche has not changed their mind about this.,
I have no idea about Elring head bolts, ( personally I would prefer the known used Porsche head bolts over "new un-known bolts", I have never seen a head bolt or head gasket failure on a M96, which is a good testimate).
I have never liked TTY torque-to-yeild bolts, taking a bolt to "yield" (brink of failure) was never a good idea to me...Getting the tension and "spring" needed for clamp load can be done without yielding the bolt (through proper metallurgy).
Porsche has made no comment or instructions on the carrier bolts so in the age of TTY bolts to be safe I would say to replace them.. ( only the bolt manufacturer knows for sure)..
For the carrier bolts, when I was building my engine, the ARP bolts were hard to find and people recommended buying new factory bolts as they don't fail. For the cost of the factory bolts, I would replace the bolts with the ARP bolts. The ARP bolts are definitely reusable and cost $129.99 compared to $105.00 for the factory bolts.
I used the ARP carrier bolts in my build. When I bought the carrier and head bolts from LN I didn�t even realize the head bolts were actually studs. These little tidbits are part of what make building this engine so difficult.
I have been using Elring head bolts on VW VR6's for years, as OEM bolts are NLA. The VR6 takes 60Nm + 180 degrees, which is hella tight for an M10 fastener. Obviously these are TTY bolts - never had a problem with the Elring bolts in this application.
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