Propane or MAPP

[Rekusu]

What ho one and all,

Will probably have to use heat to remove my car's suspension strut, pinch bolt as it is now rust 'welded.'

I have a standard plumbers torch with a cannister of propane (or may be butane?) but have been advised that MAPP will be hotter. First question, would either butane of propane get the knuckle sufficiently hot to hopefully, release the bolt? Second, if I buy a cannister of MAPP, is it likely to be the same screw fitting as my torch? More specifically, do all these torches have the same fitting? Finally, can I use a hotter gas in the standard torch?

Thanks and toodle pip

 

[Mottie]

I use the yellow canister (Mapp?) with my Rothenburger torch for heating up siezed bolts and nuts on cars.

 

[Stivino]

I've freed off siezed bolts with a Primus 2000 bottle, sometimes I've used two of them on a bolt. It has always done the job.
You can try it and it you can't get enough heat into it, try with MAPP.

 

[Tigercubrider]

I believe that MAP is hotter.
Although allegedly a Bulfinch torch on propane gets hotter

 

[Stivino]

Having just Googled it, MAPP heats up to only 100 degrees Fahrenheit more than Propane so, it probably won't make any difference.

 

[Old Salt]

I think your plumbers torch will be sufficient. I would also soak it in some penetrating oil overnight. If you don't have penetrating oil try some diesel but do be careful when subsequently using your plumbers torch

 

[Rekusu]

Gentlemen,

Thank for your replies. One thing I am not clear about, the general consensus is to heat the bolt. I know everything will expand, but surely one should heat the surrounding area in a attempt to expand the hole rather than expand the bolt?

Your thoughts appreciated.

 

[Burnerman]

Use Mapp, heat the bolt but keep the heat away from the bottom of the strut.
Take your time, you don’t want to snap it!
Use a full hexagon socket and heave away.....but replace the bolt with a new one once you’re done.
John

 

[Rekusu]

Thank you, beery grateful for the information. In applying heat, does it make any difference that it is a pinch bolt, so not only is the threaded part rusted together but probably also the non-threaded part?

Unfortunately, previous attempts to loosen is while the strut is on the car, has resulted in both strut bolts becoming rounded. And that was suing a 6 sided socket! I do have a bolt extractor and may have to hammer it on. The alternative is to get a local gent with a welder to weld another nut.

 

[Burnerman]

The main resistance will be on the threaded part, but corrosion may well have crept up to the pinch end too.
This is where oxy acetylene comes in......you can get the affected area red hot and keep the heat away from the rest.
For heat to be really effective, the bolt needs to be getting towards red heat.
You may be able to hammer on a socket that is smaller than the original bolt head - even an imperial size may rescue you.
Be lucky!
John

 

[blup]

Rothenberger with MAPP

 

[Burnerman]

Since I sold on my BOC Portapak, that's what I use.......2 of them in fact.
John

 

[Mottie]

The alternative is to get a local gent with a welder to weld another nut.

Be careful when applying heat to a shock absorber. I was welding a bracket on a motorcycle shock once, the oil got too hot and the damn thing exploded!

 

[Burnerman]

Very good advice.
I would have thought that if someone could MIG another nut on, there would be enough heat around for the damn thing to undo anyway.
Maybe Rekusu could have someone standing by just to chill the bottom end of the strut as the work progresses.
John

 

[Mottie]

I would have thought that if someone could MIG another nut on, there would be enough heat around for the damn thing to undo anyway.

Ah, yes. I was using gas when mine exploded. I don’t think MIG's were about at that time!