Siezed Precat Bolts? There might just be another way...

[Tem]

Going from ambient to -40 in a few seconds will make them very very brittle.

I really doubt that, but I could be wrong, I'm not a metal engineer  s8) s8)

I've used cold sprays and blow torches to make stuff fit and undo stuff and they never seem to mind it. Now I'm not sure if metal becomes brittle near 0K, or is it just the movies, but with a sudden 60 degree temp change around 0C...?

Cryo treatments are actually used to make metal bolts harder and they last longer under load. Also remember that steel "freezes" at 1500C, so once it cools from 1500C to 20C, I doubt even a sudden change from 20C to -40C will make much difference. It's kinda like changing ice cubes temperature from -100C to -110C.

[heathstimpson]

On a bolt though i'd be surprised if it didn't make it too brittle to undo without snapping it off.

I doubt that makes much difference to metal. Remember that some people actually drive their cars at these temperatures and they don't snap either  s;) s;)

driving is not an issue though, even in cold climates, the bolts would never see such a thermal shock, they'd go from cold to hot as the engine's heat transfered to the bolt. Going from ambient to -40 in a few seconds will make them very very brittle.

Who want's to test it   s:shock: :shock: s:shock:

It won't cause any issues as the studs, nuts etc have been tempered previously and would easily withstand this low temp easily  s:?: :?: s:?:

[Anonymous]

Tried this stuff to get my manifold off for pre cat gutting.

It works. but not really much better than ordinary penetrating oil. Also the tin says to use for 5-10 secs but this doesnt get things that cold. it needs about 15-20 secs which doesnt make the can last that long and at 5 quid a can its not that cheap compared to halfrauds £2.99 penetrating oil spray.

All in i would say if you are in a hurry it may help but it still took me 4hrs to strip my heatsheild and manifold off (only 1 sheared bolt and 1 rounded off and removed with molegrips bolt, both on the heatshield)  s:roll: :roll: s:roll:  

BTW my precats were still in perfect nick at 70,000 miles   s:) s:)   but now i have none  s:D s:D   still got to put it all back together now though - i take it refitting is the reverse of removal? but takes less time

[Anonymous]

got to put it all back together now though - i take it refitting is the reverse of removal? but takes less time

yup, took me a day n a half to strip, but 45mins to put it all back together

[Anonymous]

Sorry to drift slightly again....i'm just finishing a chemistry degree so i've seen a lot of doctors trying to impress with this stuff....best trick i've seen yet is pouring a bucket of l.nitrogen into a container full of hot soapy water......makes a massive explosion of bubbles that completley freezes in mid air! Well worth 3 years of boredom to see!