924Board.org

seanski44 · Joined: 13 Mar 2006 Posts: 532 Location: Nottingham UK

Hi,

Quick background - bought 931 as project with failed cam belt. I have a spare 931 head, so am attempting to get the head off and replace it (all being well in the block). All the exhaust is off and the Jpipe etc is all out of the way, air box and all pressure pipes are off. Am down to the head bolts themselves, but....

Car is an '81 series2 UK spec (RHD), it has the 'allen' style head bolts on it though, so its either never had the head off (can't believe that) or the bolts were reused (I'm assuming this as I'd imagine they should have been replaced with spline type bolts) One of the bolts (number 6 in the unscrewing order) was chewed before I got to it.. anyway, I assume that someone has screwed it up when torquing it back on, or has had a go at removing it in the past and failed (or both)- hence selling the car..

I put an 3/8" Hex bit in and attached my 18" torque wrench with an adapter. First, the bolt chewed the adaptor into two parts. I switched to the 1/2" hex bit (probably should have used this in the first place) and this time it rotated inside the bolt.

What's my next step? - any advice welcomed!

Arghhh, thought I've have the head off over Easter! (happy easter by the way)
_________________
1998 BMW Z3 2.8 arctic silver & red

1981 168HP 931 S2 blue/tan leather - SOLD

1985 121HP 924 2.0l na modded - SOLD!
1992 968 lux SOLD
1989 944 2.7 lux SOLD

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

Are you using SAE sized allen/hex key sockets? The head bolts use a 10mm key (for the allen/hex heads). Try it again with the 10mm key.

If that doesn't work, you're going to have to just drill the head of the bolt off - very carefully without touching the engine head itself.

Also - never use a torque wrench as a regular wrench. It's a precision calibrated instrument. I would not trust yours to read the correct torque anymore. The head bolts are very sensitive to the correct torque.

Get a new 1/2" torque wrench, a 10mm allen key socket (snap-on makes a strong 3/8" drive 10mm socket, other's I've had have snapped), a 36" breaker bar to take the bolts off, and a new set of factory head bolts (along with the triple-square socket key for them) or a set of raceware studs/nuts.

Good luck!
nick

seanski44 · Joined: 13 Mar 2006 Posts: 532 Location: Nottingham UK

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

Use a sharp drill bit, a little squirt of oil, and slow speed. You should be fine. The trick is - you won't be able to pull the head up off the remaining stud if the exhaust manifold is still attached.

You can either try and grab the stud with vice-grips if there is enough sticking up, or you might have to drill a pilot hole into it with a smaller bit and get a reverse thread to twist it out. Maybe somebody else has another idea?!

Anyway, definitely replace that torque wrench. A 1/2" click torque wrench works great. Loosen it up to 2-3lbs of torque when you store it too - so the spring inside the wrench stays healthy.

nick

seanski44 · Joined: 13 Mar 2006 Posts: 532 Location: Nottingham UK

mustangporsche · Joined: 08 Oct 2003 Posts: 283 Location: California Lodi

Well if you have a MIG welder you could tack a bolt to the head, than use a breaker bar with socket to get it off. Or just drill and use a easy out as someone else already said. Good luck, its not fun when stuff goes like this.
_________________
81 931
73 911

seanski44 · Joined: 13 Mar 2006 Posts: 532 Location: Nottingham UK

Smoothie · Posted: Wed Apr 19, 2006 2:29 am Post subject:

My guess would be that a fully torqued head bolt won't come out with a bolt extractor as long as the bolts' head is still there. You'll be left with the extractor broken off in the bolt... I think you'll have to drill off the whole bolt head first, then use the extractor on what's left. A 12mm drill bit should center itself nicely and remove the whole head. That should leave you with a V in what remains of the bolt for centering the smaller sized drill hole for the extractor.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

bulldog fred · Joined: 03 Mar 2006 Posts: 13 Location: uk - portsmouth

hi lads i agree with the mig welding idea i have used on many things in the past and you know you are getting a result if you do a good weld!!, try other ways first if they do not succseed then you know it can be done this way if all else fails....
_________________
bulldog fred
1980 931 s1 silver
1982 931 s2 red - moded intercooler, water injection, avo sports suspension 944 turbo sway bars,green stuff brakes (brilliant)

Paul · Posted: Wed Apr 19, 2006 9:20 am Post subject:

Get the next closest sized allen wrench and file a slight taper into the front of it. Then jam it in the headbolt with a hammer.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

nowivdunit · Joined: 08 Apr 2006 Posts: 6

These might worktoo.

http://www.sears.com/sr/javasr/product.do?BV_SessionID=@@@@1926639686.1145405908@@@@&BV_EngineID=ccjcaddhigghgkicegecegjdghldgfi.0&pid=00952160000&vertical=TOOL&ihtoken=1

seanski44 · Joined: 13 Mar 2006 Posts: 532 Location: Nottingham UK

thanks guys, all good advice, will try the 'next size allen' method first.

Sorry, sears catalogue link didn't work for me so I haven't any idea what you suggested!

as for the mig welding, well, that will be last resort as it'd mean giving in and paying for the car to be trailered to someone who could do that...
_________________
1998 BMW Z3 2.8 arctic silver & red

1981 168HP 931 S2 blue/tan leather - SOLD

1985 121HP 924 2.0l na modded - SOLD!
1992 968 lux SOLD
1989 944 2.7 lux SOLD

nowivdunit · Joined: 08 Apr 2006 Posts: 6

Paul · Posted: Fri Apr 21, 2006 12:39 pm Post subject:

I have a set of those and they are awesome! I don't know if there is enough space to use them on headbolts however.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Lizard · Posted: Fri Apr 21, 2006 2:18 pm Post subject:

actually once the head of the bolt is removed/drilled off it will be very easy to remove the rest of the bolt, as the washer which should be under it should leave enough of a grip for needle nose pliers to turn it. and once the head is removed all torque is removed from the bolt and it should turn with ease.
_________________
3 928s,