Broken cylinder head bolts

clinton2006 · 30 December 2010, 19:37

Hello all out there, has any one got any idea on how to free up seized bolts. I would normally give them a good dosing of WD40 but are frightened of undoing them and breaking them as i have done in the past.
Come on chaps some one out there must have a good idea.

jyasaki · 30 December 2010, 20:13

1) Heat the area. I'm assuming you're using steel bolts into aluminum; aluminum will expand at a faster rate than the steel, hopefully breaking whatever seizing them.

2) Liberal doses of a good penetrating oil should help (be careful if you do this before resorting to option 1 above.)

3) An impact driver may break loose a bolt that a regular wrench won't. Problem is that you will have less "feel" for what's happening with the bolt. Not that that matters all that much: once you feel the give of the bolt failing, it's pretty much too late.

That's about all I've got. I'm sure there are other techniques out there.

jky

Bigmuz7 · 30 December 2010, 20:51

I like to follow the 'only get one chance' type of idea , cos if you bust the bolt head .. life is gonna get a whole lot more difficult... and expensive

,.. what are we talking for the bolt head, 13,14 mm ?

Ive developed a canny sense of how much leverage is good on my half inch socket wrench !

Whats the motor ,, why is it seized , what have you tried etc etc .. more info would be good

Nos4r2 · 30 December 2010, 23:11

This is one of the reasons I don't like Suzuki 2 strokes much-bolts rather than studs and nuts.
They should be M8 bolts
Here's how I deal with the really awkward ones.It takes a long time, but if it doesn't work, nothing will.
Wire brush,heat from a blowtorch directly on the bolt head, plusgas on the bolt, leave to cool. (in that order).Do this twice the first day, then,every day for 5 days.
Before you try and undo the bolts, using the tools listed below, give each bolt a shock (smart tap) in the wrong direction (ie, doing it up).
Undo by shocking using a 6 sided socket,a stiff, short breaker bar and a wooden mallet (It's more controllable than an impact driver).You don't need to really whack it hard- smarts tap are enough.

As soon as one moves, get the tension off it,get some plusgas onto it and move onto the next one. Don't remove them yet-you may need to retighten the loose ones in order to get the last couple of bolts undone.Undo each one as though you're cutting a thread with a tap as it's quite likely there'll be a load of crud in the thread. Use plenty of plusgas/WD40 (either will do at this stage) to keep the thread lubricated.

Downhilldai · 31 December 2010, 01:14

Quote:

Originally Posted by Nos4r2

This is one of the reasons I don't like Suzuki 2 strokes much-bolts rather than studs and nuts.
They should be M8 bolts
Here's how I deal with the really awkward ones.It takes a long time, but if it doesn't work, nothing will.
Wire brush,heat from a blowtorch directly on the bolt head, plusgas on the bolt, leave to cool. (in that order).Do this twice the first day, then,every day for 5 days.
Before you try and undo the bolts, using the tools listed below, give each bolt a shock (smart tap) in the wrong direction (ie, doing it up).
Undo by shocking using a 6 sided socket,a stiff, short breaker bar and a wooden mallet (It's more controllable than an impact driver).You don't need to really whack it hard- smarts tap are enough.

As soon as one moves, get the tension off it,get some plusgas onto it and move onto the next one. Don't remove them yet-you may need to retighten the loose ones in order to get the last couple of bolts undone.Undo each one as though you're cutting a thread with a tap as it's quite likely there'll be a load of crud in the thread. Use plenty of plusgas/WD40 (either will do at this stage) to keep the thread lubricated.

Spot on, Nos

(and stop slagging off Soozooks

)

Also, give the bolt a sharp clout with a hammer, directly onto the head before going at it with the socket. This shock helps to free off the fusion caused by the inevitable corrosion between the steel bolt & aluminium casting.

jwalker · 31 December 2010, 01:16

Hammer the heads too, (end on not sideways) it shocks the thread and helps break the seize in the block.

Downhilldai · 31 December 2010, 01:17

Quote:

Originally Posted by jwalker

Hammer the heads too, (end on not sideways) it shocks the thread and helps break the seize in the block.

Beatcha to it

jwalker · 31 December 2010, 01:46

Aye but great minds think alike.

verstappen · 31 December 2010, 16:24

SS bolts are soft, only hammer with red copper, aluminium or non metallic

free · 31 December 2010, 22:44

Personally I'd hammer them till they're a right odd shape (but still hex shaped) as JW and DHD said. I've been doing it for years and haven't broken a bleed nipple since I started. If they're accessible, then fit a ringer first and hammer till it's nice and tight. Breaks the corrosion and possibly some of the elastic tension in the bolt (but that might just be in my head.) Obviously don't re-use the bolts.

free