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I went to change out the gearbox oil the other day. The vent screw loosened up fine but lower bolt is frozen. I sprayed WD 40 and left. Hopefully it will seep into the threads and allow the drain bolt to loosen, if not, what to do next? I don't want to end up breaking off the top of the screw with too much torque.

Carefully heat with a pencil tip blowtorch

impact driver, the kind you smack with a hammer,used at all motorcycle shops,for steel screws into an aluminum case

There are substances that are more effective than WD-40 for loosening frozen bolts. Might want to try one of those.

gregor wrote:I went to change out the gearbox oil the other day. The vent screw loosened up fine but lower bolt is frozen. I sprayed WD 40 and left. Hopefully it will seep into the threads and allow the drain bolt to loosen, if not, what to do next? I don't want to end up breaking off the top of the screw with too much torque.

dlandersson wrote:There are substances that are more effective than WD-40 for loosening frozen bolts. Might want to try one of those.

gregor wrote:I went to change out the gearbox oil the other day. The vent screw loosened up fine but lower bolt is frozen. I sprayed WD 40 and left. Hopefully it will seep into the threads and allow the drain bolt to loosen, if not, what to do next? I don't want to end up breaking off the top of the screw with too much torque.

I too would hit it with a little heat from a pencil tip flame, but do be careful, and do have another washer for it (which you should replace anyway). Gentle impacts should pop it right off. Steel on aluminium can get obstinate.

This stuff is the best I've used as penetrating oils go.

Definitely go with the penetrating oil mentioned above. Far better than WD! If your lower drain plug is a hex socket, insert the tool into it and lightly tap the side of it, around in a circle - after its had an application, or two, of penetration agent. Heat will help, but be very careful you don't blister the paint doing it. At first just use it moderately to wick the oil deeper into the threads, then try with the impact driver.

R.

Since my time in the aircraft industry, I have been using Kroil http://www.kanolabs.com/ - the stuff is great on frozed bolts and also in air tools.

Don't just put it on - give it some time - up to 24 hours - to work.

Crikey wrote:Definitely go with the penetrating oil mentioned above. Far better than WD! If your lower drain plug is a hex socket, insert the tool into it and lightly tap the side of it, around in a circle - after its had an application, or two, of penetration agent. Heat will help, but be very careful you don't blister the paint doing it. At first just use it moderately to wick the oil deeper into the threads, then try with the impact driver.

R.

"The April/May 2007 edition of Machinist's Workshop did a test of penetrating oils where they measured the force required to loosen rusty test devices. Buy the issue if you want to see how they did the test. The results reported were interesting. The lower the number of pounds the better. Mighty interesting results for simple acetone and tranny fluid!

Penetrating oil . Average load .. Price per fluid ounce
None ................. 516 pounds .
WD-40 .............. 238 pounds .. $0.25
PB Blaster ......... 214 pounds .. $0.35
Liquid Wrench ... 127 pounds .. $0.21
Kano Kroil ........ 106 pounds .. $0.75
ATF-Acetone mix.. 53 pounds .. $0.10

The ATF-Acetone mix was a 50/50 mix (1 to 1 ratio)."

~Rich

Thats interesting as I have always used blaster/ liquid wrench with heat and low pressure air tourq driver, but a 50/50 mixture with Tranny fluid and acitone gives a much less rated removel.
I always have used acitone to remove rust and free bolts that won't harm surface but needed to rince off with water less than 3 min. to neatullize the acetone and muriadic acid/ hydrocloric acid.(Hydrocloric will remove all yellow stains on hull, spray on , let sit for 2 min. and rince with fresh water. Like new).
Wonder if the Tranny fluid stabilize/furlong the acitone to leave on longer.
I will try this at my work as I run into rusted bolts to 1 inch diamiter all the time.(small drops of each at a time, don't want a mass build up)
Dave

Hamin' X wrote:"The April/May 2007 edition of Machinist's Workshop did a test of penetrating oils where they measured the force required to loosen rusty test devices. Buy the issue if you want to see how they did the test. The results reported were interesting. The lower the number of pounds the better. Mighty interesting results for simple acetone and tranny fluid!

Penetrating oil . Average load .. Price per fluid ounce
None ................. 516 pounds .
WD-40 .............. 238 pounds .. $0.25
PB Blaster ......... 214 pounds .. $0.35
Liquid Wrench ... 127 pounds .. $0.21
Kano Kroil ........ 106 pounds .. $0.75
ATF-Acetone mix.. 53 pounds .. $0.10

The ATF-Acetone mix was a 50/50 mix (1 to 1 ratio)."

~Rich

That's great. A liter of Acetone is really cheap!
It has really low viscosity and would penetrate any crack or pore, before evaporating. I think transmission fluid is a pressure resistant lubricant.

Yeah, but Liquid Wrench is pretty effective and has no acid/toxic issues.

Crikey wrote:That's great. A liter of Acetone is really cheap!
It has really low viscosity and would penetrate any crack or pore, before evaporating. I think transmission fluid is a pressure resistant lubricant.

dlandersson wrote:Yeah, but Liquid Wrench is pretty effective and has no acid/toxic issues.

Crikey wrote:That's great. A liter of Acetone is really cheap!
It has really low viscosity and would penetrate any crack or pore, before evaporating. I think transmission fluid is a pressure resistant lubricant.

Same here, it's worked every time for me as well. But, for the extremely small number of times you're facing down a snapped bolt, or stripped thread, you wouldn't be melting the polar cap keeping a small vial around. Actually, instead of buying a liter, you'd just need a small bottle of nail polish remover ..... Thanks' Admiral!

I think nail polish remover is usually a solution of either acetone or ethyl acetate in water.

I don't think that will have the penetrating qualities of pure acetone.

All you are really doing here is thinning the lubricant enough so that it can seep into small spaces and reach the threads through the corrosion. A water solution will have a lot more surface tension , although I always had trouble with tribblology....

Acetone is available in a half liter size bottle at hardware stores. Acetone is highly toxic and is linked to cataracts...use it outside or lots of ventilation, and nitrile gloves.

It is highly flammable...keep those torches away from it too.

Muriatic/Hydrocric acid will destroy rust. Be very carefull how you use it and rince off with water soon.
Dave

Catigale wrote:I think nail polish remover is usually a solution of either acetone or ethyl acetate in water.

I don't think that will have the penetrating qualities of pure acetone.

All you are really doing here is thinning the lubricant enough so that it can seep into small spaces and reach the threads through the corrosion. A water solution will have a lot more surface tension , although I always had trouble with tribblology....

Acetone is available in a half liter size bottle at hardware stores. Acetone is highly toxic and is linked to cataracts...use it outside or lots of ventilation, and nitrile gloves.

It is highly flammable...keep those torches away from it too.