propane hot enough for broken bolt removal?

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dummyaccount@electricant.net - 29 Dec 2004 23:08 GMT

long story short, a small (1/4" 5/16" diameter?) thermostat housing
bolt broke. about 3/8" of it is sticking out of the aluminum engine
block, with the cap missing. i want to heat it up, but only have access
to a cheap propane torch. will this do any good? i was thinking that
heating, then one of the craftsman socket-like removal tools.

thoughts? there isnt any chance of damaging/warping anything with a
measly propane torch, right?

thanks,
anthony

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Glen Cooper - 30 Dec 2004 05:12 GMT

> long story short, a small (1/4" 5/16" diameter?) thermostat housing
> bolt broke. about 3/8" of it is sticking out of the aluminum engine
[quoted text clipped - 7 lines]
> thanks,
> anthony

If you can take a set of ViseGrip pliers and secure the pliers to the bolt
after being heated, and heat the area surrounding the bolt first til it gets
hot but not too hot to change the color of the flame of the torch or turn
the metal too red and then apply the heat to the bolt for only a second or
two then if you take it easy but not to easy then the bolt will come out.
Be carefull. Your problem is caused by the different properties of the bolt
compared to the aluminum manifold. It is a common problem. Consider
yourself lucky it exposed 3/8 inch to grab onto.

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pater - 30 Dec 2004 12:13 GMT

If you have the time, soak it with penetrating oil a few times a day
for a few days, whack it straight on with a hammer every time you do.
This will save heating an aluminum manifold or head where warpage may
occur if you do. Then carefully do the visegrip thing & work it til it
comes out. Just a sugestion.

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Ted Mittelstaedt - 31 Dec 2004 08:59 GMT

> long story short, a small (1/4" 5/16" diameter?) thermostat housing
> bolt broke. about 3/8" of it is sticking out of the aluminum engine
> block, with the cap missing. i want to heat it up, but only have access
> to a cheap propane torch. will this do any good?

Yes, it will. Aluminum expands at a higher rate than steel so even
just heating both parts will cause the bolt to be 'looser' in the
aluminum casting. Note that it is perfectly possible to -melt-
aluminum with a propane torch.

note also that it is quite easy to destroy aluminum threads in
this kind of operation.

> i was thinking that
> heating, then one of the craftsman socket-like removal tools.
>
> thoughts? there isnt any chance of damaging/warping anything with a
> measly propane torch, right?

There is a chance of warpage. What I would suggest is you go to an
electronics distributor or computer supplier and buy a can of "freeze spray"
this is sold specifically to find thermal intermittents on circuit boards,
the
can costs about 6 bucks.

Next, heat up the thermostat housing slowly, moving the flame around.
Aluminum conducts heat very well and will wick the heat away from the place
you
heat up, which is what you want. Let the entire manifold get hot, to
around 210 to 220 degrees. Use a thermometer, you can get laser
thermometers now that are pretty cheap. Once everything is nice and
hot, hit the stud with the freeze spray for about 15-30 seconds, try not
to get it on the manifold. Then, quickly before the stud can absorb heat
from the manifold again, use the vice grips to turn the bolt out.

If you can't get it out then the best bet is to use a grinder and flatten
the
top of the bolt, then use a center punch to make a good solid dimple
in the exact center of the bolt. Then use a well-sharpened drill bit to
drill down the center of the bolt, go very slowly, carefully, and absolutely
down the center. Use a large bit that it a slightly smaller diameter than
the
bolt. Then follow this with a heli-coil kit.

Ted

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The Cat - 31 Dec 2004 18:26 GMT

> Next, heat up the thermostat housing slowly, moving the flame around.
> Aluminum conducts heat very well and will wick the heat away from the
[quoted text clipped - 4 lines]
> to get it on the manifold. Then, quickly before the stud can absorb
> heat from the manifold again, use the vice grips to turn the bolt out.

You may have to repeat this over and over whenever the stud gets stuck as
you try to remove it. Work the stud back and forth as you remove it to
keep it moving better (turn, back a bit, forward a bit, back a bit,
turn...). Keep the piece turning as much as possible, working it back and
forth if it is sticking - keep it as loose and free turning as possible.
Use lots of patience, it is comparatively cheap to everything else.

> Then use a well-sharpened drill bit to drill down the center of the
> bolt, go very slowly, carefully, and absolutely down the center.

Avoid going here, if possible.

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