Rounded allen bolt - Help !

HF2

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I am in the prcess of taking my cylinder head off for a head gasket replacement, however I am now stuck because I have managed to strip one of the allen bolts. I have tried heat and mole grips but no joy.

I need advice on the best way to remove the bolt without damaging the chain cover. :wallbash:
 
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John

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Hmm, your light on room there.

If you have high quality sockets, you can try and hammer one slightly smaller onto it.

Or, cut the face of the bolt perpendicular to the thread direction with a hacksaw enough to get in a stubby screwdriver head in and then twist that?
 

John

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Or maybe hammer in a slot head which is just slightly wider than the widest point within the head (although you might struggle with the length of driver with that size of head)...
 

Colin_b

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Small Stillson (pipe) wrench. But gently, there is plenty of room.
 

hotrodjon

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What I have done in the past on other cars in desperation is to weld a nut on. Quite often the direct heat generated can help free the bolt and then with a nut welded on you can use a ring spanner or socket. Once it is out you can replace it with a new bolt.
 

Mercsys

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Take a similar bolt along to a good tool outlet and get a socket to be driven over or into the head, you could get lucky with a big torx, bi-hex or bi-square socket, the act of hammering the socket on/in could make it an easy removal job. While you are at it get a set of these they are the dogs, the best quality I have used.

WERA|950 PKL/9 BM N|HEXAGON WRENCH SET, BALLPOINT | Farnell United Kingdom

WERA|967L/9 HF TORX|TORX L KEY SET, WITH HOLDING FUNCTION | Farnell United Kingdom
 

lupi

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If it was mine, I would spray generously penetrating oil,at pionts where it is
possible to penatrate, leave it over the night.

Next step, will use sharp ( i.e not strong enough to damage the chain cover) rubber mallet blows on the head of the bolt ( the idea is to free the corrossion from the lenght of the bolt ) first action try a tightening movement on the bolt, ( use tools as defined on the other posts) followed by untightening movement, repeat this procedure for several times, the least movement will mean the bolt has surrendered, don`t try to unbolt in one attempt, you must have patience, with every anticlockwise turn go back to a clockwise movement.

If the bolt is that much stubborn, then go to plan 2, use a good hacksaw
and cut from the back side of the bracket, i.e. the aluminum water jacket,
when you have the cover on workbench,then you can continue to cut
the aluminum water jacket and so freeing corrosion on stem of the bolt
keep using penatrating oil,eventually it will come off.

Obviously you will need to buy replacement water jacket.

Good Luck.
and if necessary
 

janner

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Mole grips and allen key together.
 

Druk

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Does that bolt absolutely need to come out to get the head off? Looks like all it holds on is a lifting eye and the water elbow.
 

Will

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As above - or worst case, cut the head off flush with the bracket and deal with it once the cylinder head is off the car :)
 

Dieselman

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Try cutting both sides of the head off about 1/4 the way in and use a regular spanner on the rest of the head, but as already said, does it need to come off at this stage?
 

Tiff

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Vise Grips. Not Mole grips or vice grips. The proper real deal ones would get that off in a jiffy.
 

Stratman

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These are worth their weight in gold. I have a set and can confirm they'll remove a perfectly rounded bolt. They give both grip and leverage.
 

jepho

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Loads of good advice here. You could try the good idea from Dieselman ( I love that avatar) and I would add using Plusgas penetrating oil. My other advice is before loosening very tight nuts or bolts, set-scews, studs, cap-heads and the like, I like to break the seal first by tightening them a very small amount.
 
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horgantrevor

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a torques socket set use one bigger and tap home then put on socket ratchet now as you try to open tap the socket ratchet with a hammer directly over the bolt and out she will come
 

kth286

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those bolts need to be undone as they screw into the head.

the water return goes through the timing cover and into the head via a seal so that water does not leak into the timing cavity.

torque applied to bolts is (I think) 21 Nm.
 

A-AvantGarde

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These are worth their weight in gold. I have a set and can confirm they'll remove a perfectly rounded bolt. They give both grip and leverage.

Are they really that good? Some of the JML tools I've tried in the past haven't been of the greatest quality. For £6 that looks like a useful tool to have.

Just be interested to hear how durable / well made they appear to be.
 
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OP
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HF2

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These are worth their weight in gold. I have a set and can confirm they'll remove a perfectly rounded bolt. They give both grip and leverage.


I had a set of those, the large one broke when I sued it in anger one day. I've still got the smaller one in a tool box somewhere I'll dig it out and have a go with it.
 

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