heat.

[roxylass]

how long can you safely heat the block up to get a seized bolt out, it is one of the four that hold the water jacket on,don't want to heat to much in case i damage the ally. i have had to take it off to clean the water passage.

[Horsley-Anarak]

I find that 8 out of 10 times they will just shear off.

If the heads of the bolts shear off, you are left with enough bolt to get some heat on.

Get the bolt red and then use molegrips.

I also have found that tapping the end of the bolt axially helps to loosen the threads.

Worst case you will need a 5/16 BSF tap.

Good luck

H-A

[Jerry In Maine]

aluminum melts at ~1200*F. you likely won't get it that hot (unless you're using an oxy/acet torch), especially when its firmly attached to a large heatsink like a cylinder.

As H/A says - heat the bolt red hot, then let cool.try this several times...seems the hot/cool cycles work the corrosion loose.

if you wind up giving up on the heat you might try flipping the motor and filling the water jacket with penetrant through the cooling water outlet, letting it sit for a few days then trying again.

[Hugz]

For the Aussies we don't have mole grips... they are called vice grips. Had me non-plussed there for a while. No moles down under... well, not the burrowing type anyway

[roxylass]

got the bolt glowing, vice gripes on then it snapped clean with the face of the block . seen a tool called easy out but will this be strong enough to free the bolt,also I'm not very mechanical so what exactly do i do with a 5/16 tap, i,m guessing it will put the opposite way thread in the seized bolt, then put a 5/16 bolt in tighten it keep turning it and that should wind the other one out.

[Keith.P]

Never liked easy out's, if one snaps off, that's your lot, centre punch the stud and drill it out, then re-tap.

[Horsley-Anarak]

Bad luck.

The century cylinder that I showed a picture of was the same, 3 out of 4 broke off.

Tapping Drill 5/16 BSF 6.75mm 0.2655 inch 17/64 inch, you need to drill out the stub of the bolt that is left in the cylinder.

This can be quite tricky, you need to drill down the exact middle of the bolt.

Once you have drilled it out you re-tap the thread. With luck the tap will follow the old thread, if it goes wrong you will end up with a 5/16th size hole.

If that happens, then I go up a size and make the thread 10mm (tapping drill 8.5mm). 10mm stainless bolts are cheaper than BSF.

If you think that you may not have the skills to do this, then take it down to your local engineering shop and ask them to do it for you. Where do you live? there may be someone on the forum that may be able to help you.

I would not use an "easy out" myself. In the past I have broken them off in the stud, which creates a whole new problem.

Before you spend too much time, I would clean out the waterways and make sure the cylinder is worth recovering.

Make sure that there are no cracks in the water jacket, these can sometimes show up when you start getting the rust out.

H-A

[roxylass]

dont see anyone on the forum near me, i stay in inverkeithing fife bonnie scotland.

[Horsley-Anarak]

inverkeithing only 444.8 miles from my house.

Might be a bit far.

H-A

[roxylass]

ah well gave it a go,small drill through the centre of the bolt looks like i went to far,sure it,s went through the ally casing.
was a lot more carefull with the other drill bits,thing is i thing there is still a sliver of the seized bolt round the sides will the 5/16 tap get rid of that, if so that will be the job done.

[roxylass]

finally got it done,tapped a new thread with the 5/16th tap, new bolt married the thread no problem cleaned all the waterways, reassembled ran it in the test tank, dear dear water coming out but less than what there was, now it is coming out of the top of the exhaust silencer.

[Horsley-Anarak]

is water jacket cracked?

H-A

[roxylass]

the water jacket looks fine,nothing escaping from there, thinking maybe the water pipe has come loose at the top.

[roxylass]

found the problem, the rotor cracked right through and only one vane left on it, many thanks HA and everyone else who gave advice. also going to re-new all the bolts with s/s ones. problem solved .