Blow lamps

Post by **Mick_Anik** » Thu Aug 06, 2009 11:18 pm

I was doing cars for decades before it clicked with me - I can't understand why. I've worked with mechanics in the trade and with various people, but never saw it done, although I'd seen guys use oxyacetylene to the same end - very odd, the whole business.

Blow lamps........if you're struggling with a nut or bolt, get the blow lamp on it, using the minimum of heat to get it moving. Then start with lubrication (not so quickly that it flares up!) and a backwards and forwards action with the socket or spanner - this cleans up the thread a little as you proceed - and only use more heat as necessary. Try to avoid getting anything red......a blue colour indicates a high level of heat.

Once the object is warm, a heavy hammer blow can help, or a blunted chisel on the side of the bolt head or nut if there no access for the hammer. Shock treatment!

I stripped an ancient Minor a couple of years ago, and got everything off intact, thanks to my trusty blowlamp.

The usual care advice applies - petrol, rubber parts, flammable materials in close proximity etc etc. Everybody else out of the workshop, or far away if outside.

Post by **alzax3** » Fri Aug 07, 2009 7:40 pm

Yup, you'd have a job dismantling a classic tractor without heat, so there's no reason why cars should be different..... basically you're just using heat to expand the hole in the nut breaking the hold that time/habit/corrosion have between it and the bolt. Bizzare thing is that it works on things like brake bleed nipples (carefully) so that must be a case of expanding the nipple thread, and hence the tapped hole, so that it's all a bit looser when it cools at a slightly different rate.......

Post by **rayofleamington** » Fri Aug 07, 2009 9:39 pm

Garages tend to use Oxy because that's what they've got.
I use my plumbing blowlamp for lots of non-plumbing things!
One of the last car jobs I used it for was to remove paint and underseal from an area the I was going to mig weld.

Post by **Mick_Anik** » Fri Aug 07, 2009 9:57 pm

Alzax3 here seems to have the right idea. You have to remember that things are softer when they're hot, so you have an increased chance of breakage if you're not careful with the spanner.
Sometimes its a good idea to go to hot and back to cold a few times before going in and trying to turn it, when it's just warmish.

Forgot to point out for the uninitiated......blowlamps can come with a range of tips - the thin pencil type for accuracy and very localised heating, a flat, wide one like a fan (ideal for Ray's paint and underseal removal), and the general flame-thrower type (mosquito annihilation!).

Blow lamps are also great for soldering up radiators and the like, either with the bare flame or with the copper tip that came with mine.

A 'must-have', really.

Post by **leyther8008** » Fri Oct 30, 2009 10:10 am

If you do get anthing red during heating dont re-use it as you,ve probably annealed, it losing any heat treatment properties it might have had, especially applicable to higher grade nuts and bolts used in the suspension.

Post by **edjones** » Fri Oct 30, 2009 5:56 pm

Any recommendations on a good lamp for DIY use or all they all much of a muchness?

Post by **MarkyB** » Fri Oct 30, 2009 8:46 pm

Much of a muchness I'd say.
Take a look at the price and availability of refills and buy a spare when you buy the blow lamp.
I'm on the lookout for one that fits on a camping gas cartridge as I can often pick them up for £1.

Post by **bmcecosse** » Fri Oct 30, 2009 9:34 pm

Yes - the Camping Gaz ones are very useful - not as powerful as an oxy torch of course - but ok for what they are!

Post by **Jefftav** » Fri Oct 30, 2009 11:02 pm

When I was stripping down a car for spares a mate said to heat bolts, nuts etc... until the colour was changing (bluey colured not glowing red) and either immerse or pour cold water on it. You hear a crack and hey presto usually the nut will come off. I did this a few times when I was really stuck and it did work.

Another useful tip though is wire brush the threads before starting and soak with plus gas and use lubricant when taking off the nut to make life easier. Especially if you want to re-use the nuts and bolts.

Post by **Leo** » Fri Oct 30, 2009 11:31 pm

Never found one yet that works in very cold temperatures

Leo 69 Traveller

Post by **bmcecosse** » Fri Oct 30, 2009 11:33 pm

Just keep the gas can warm!

Post by **billlobban** » Sat Oct 31, 2009 11:37 am

Really cold - minus 20 odd - stick the cylinder in a bowl of hot water for a few minutes. Repeat the process as as often as necessary. Works a treat.

Post by **MarkyB** » Sat Oct 31, 2009 5:50 pm

You can also get a blow lamp that fits on the large gas cylinders used in heaters.
Should be very cheap to run if you have one of those heaters in your garage.

A tip I saw on a US site was too heat the offending part up then hold a candle against it.
The theory is that the wax gets drawn into the threads.

The screech that things make as they come apart after many years is very satisfying.