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jenevers

undoing exhaust manifold bolts

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If all else fails and you can get at them you might have to saw down the length of them without damaging the threads of the studs and try to fiddle the remaining bits off somehow. Worth a try or you can end up with broken studs and then you have to take the head off then you damage the head then you find you can't get one then you need a new engine then you might as well get a new boat ..........

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33 minutes ago, mark99 said:

Try plus gas. I did same recently and it worked.

If that fails, heating them up usually works. 

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Brass was often used for exh man nuts as it is less prone to seizing.

 

Also, being weaker, brass nuts will break and leave the steel stud intact.

 

And a bit of heat helps.

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22 minutes ago, jake_crew said:

Brass was often used for exh man nuts as it is less prone to seizing.

 

Also, being weaker, brass nuts will break and leave the steel stud intact.

 

And a bit of heat helps.

In my mini-owning days I always replaced the manifold nuts with brass ones.   Old A35 ones were best as they were deeper than standard nuts which made it easier to get a spanner on.

 

Of course you need to do this before the nuts are rusted onto the studs.

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Are they bolts? Not unheard of but fairly unusual.  If bolts use a flat ended punch and a small hammer.  With the punch on the bolt head and using light, rapid blows with the hammer.  If steel nuts and studs, forget what size they should be, instead use a spanner that can be persuaded to fit, even if you need to tap it on.  I don't usually abuse tools but this is an exception.

If time permits, build small "cups " under each stud/bolt, these can be out of blue tack or plasticine and then fill these with penetrating fluid.  Think Swallows nests......

 

To clarify, the punch method isn't to undo the bolt, it's to shock the threads, so used on the bolt head, axially.

 

 

 

 

Edited by NB Esk
Clarity

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20 minutes ago, john.k said:

Bolts or studs?-----big difference in outcomes.....#1 says bolts.

in the title, yes. In the text he says nuts so we are still guessing but nuts seem more likely.

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Everything said above by others.

 

Another method of shocking in order to break the seal is to try tightening it as well as untightening. I think I've said this before on here, more than twice times.

Best to use a socket if you can or a ring spanner, open ended ones slip easily and round off corners before letting you smash your knuckles and rip skin.

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Running the engine before trying to loosen them should help by providing heat in the area.

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39 minutes ago, BWM said:

Running the engine before trying to loosen them should help by providing heat in the area.

You would think so.  Practically, I've had little success using that method.  In my post above, I purposely didn't mention heat because the diy mechanic is less likely to have access to useful heat.  If you run an engine, everything will come up to temperature at about the same rate, whereas what's needed is for the nut to expand much quicker in order to release its hold on the stud.  A fine welding tip played onto the nut, bringing it quickly up to red, while the stud stays black would be ideal.

 

 

  • Greenie 2

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On 15/06/2019 at 11:09, john.k said:

Bolts or studs?-----big difference in outcomes.....#1 says bolts.

Actually both. Studs on the exhaust manifold and nuts on the water cooling manifold. Hope I don’t ever need to undo either but there are 2 short rubber hoses on the water manifold that will have to be changed sometime ( hopefully not in my lifetime!)

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8 minutes ago, jenevers said:

Actually both. Studs on the exhaust manifold and nuts on the water cooling manifold. Hope I don’t ever need to undo either but there are 2 short rubber hoses on the water manifold that will have to be changed sometime ( hopefully not in my lifetime!)

Cast iron head?

 

 

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15 minutes ago, jenevers said:

Hope I don’t ever need to undo either but there are 2 short rubber hoses on the water manifold that will have to be changed sometime ( hopefully not in my lifetime!)

You used to be able to get these as convoluted so they would compress and enable you to fit them with the head on.

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Doubtful hoses can be bound tightly with several layers self amalgamating tape, which in effect makes a new hose over the old. You may need to fit lager clips.  Everyone should keep a reel of it, amazing stuff.

Edited by bizzard

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On 15/06/2019 at 09:35, NB Esk said:

Are they bolts? Not unheard of but fairly unusual.  If bolts use a flat ended punch and a small hammer.  With the punch on the bolt head and using light, rapid blows with the hammer.  If steel nuts and studs, forget what size they should be, instead use a spanner that can be persuaded to fit, even if you need to tap it on.  I don't usually abuse tools but this is an exception.

If time permits, build small "cups " under each stud/bolt, these can be out of blue tack or plasticine and then fill these with penetrating fluid.  Think Swallows nests......

 

To clarify, the punch method isn't to undo the bolt, it's to shock the threads, so used on the bolt head, axially.

 

 

 

 

Mike Tyson used the punch method to knock a head off.

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13 minutes ago, bizzard said:

Doubtful hoses can be bound tightly with several layers self amalgamating tape, which in effect makes a new hose over the old. You may need to fit lager clips.  Everyone should keep a reel of it, amazing stuff.

Provided the hose isn't leaking to start with, or a bit of plastic is incorporated into the binding. SA tape eventually  balloons quite spectacularly if over a pinhole leak. 

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2 minutes ago, Iain_S said:

Provided the hose isn't leaking to start with, or a bit of plastic is incorporated into the binding. SA tape eventually  balloons quite spectacularly if over a pinhole leak. 

Yes, if the old hoses reinforcing is bust bind it closely with thin locking wire, even copper strands from a cable will do before applying the tape.

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18 hours ago, bizzard said:

Doubtful hoses can be bound tightly with several layers self amalgamating tape, which in effect makes a new hose over the old. You may need to fit lager clips.  Everyone should keep a reel of it, amazing stuff.

didn't see you as a lager man Biz.

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44 minutes ago, dor said:

didn't see you as a lager man Biz.

Iron Bru.  Made by bizzard.......from Meccano.

 

 

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On 16/06/2019 at 14:53, NB Esk said:

You would think so.  Practically, I've had little success using that method.  In my post above, I purposely didn't mention heat because the diy mechanic is less likely to have access to useful heat.  If you run an engine, everything will come up to temperature at about the same rate, whereas what's needed is for the nut to expand much quicker in order to release its hold on the stud.  A fine welding tip played onto the nut, bringing it quickly up to red, while the stud stays black would be ideal.

 

 

Your method is certainly the best with access to the necessary equipment but for someone without it is worth a try. I have also seen exhaust manifold nuts drilled parallel to the stud, allowing them to break before the stud - or split with a chisel along the hole.

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