SEIZED RUSTY BOLTS AND STUDS

[Jake]

SEIZED RUSTY BOLTS AND STUDS

Before risking shearing off those delicate exhaust fixings it is worth a look at this data.

The information was lifted from the Car Data pages of the Honest John website. I assume where lbs are quoted that this means foot/lbs of torque. I do not have the details of how the experiments were controlled, but bearing in mind there are no commercial vested interests involved with the most effective treatment it is well worth a look.

RUSTED BOLT RELEASE
Ave pounds required
516 lbs No Treatment
238 lbs WD 40
214 lbs PB Blaster
127 lbs Liquid Wrench
106 lbs Kano Kroil
53 lbs 50/50 mix of Auto Tranmsission Fluid + Acetone

CAR DATA
Honestjohn

[mark75]

I would love to read how they came to their conclusions. [research, procedures, etc.]

[Crazy_Russian]

I would love to read how they came to their conclusions. [research, procedures, etc.]

2nd that
all 6 bolts/nuts would have to be identical. on top of that, doing just one of each is not significant enough. n=3 should provide more accurate average...
anyone wants to do this experiment? :-D

[Flyingdog]

anyone wants to do this experiment? :-D

No thanks. Probly enough diverse info on the web to last a lifetime. Besides, don't really remember the last time I've somebody saying: "Holy Crap...that took 253# of torque to break that %@#*&^#@ 'n bolt free".

[XV535]

If I remember correctly the Honest John website did give the full info on how the experiments were carried out, I copied the results only a long time ago.

With reference to not caring about knowing what torque is involved in breaking the rust, I can understand that, but it is not about the numbers, but about what the shear stress of a bolt is. If the shear stress is for example 80 lb/ft and the rust is creating an 120 lb/ft grip on the thread then a sheared bolt is inevitable.

On a slightly different tack. I had some 6mm screws firmly jammed in a Mikuni carburettor yesterday, on both the lloat chamber and the diaphragm covers, and they really did not want to shift. I slotted them with cutting wheel in a Dremel, but they were still firmly jammed.

I had to put plasticine around them to make a well to put release fluid in, andafter a soak they were still tight.

With a carb (even when fully purged of fuel) you do not want to warp it by using a blowlamp, but I needed to try thermal shock. I found a very large 3/4 inch bolt and put it in the vice, heated its end to cherry red with a high heat gas torch, and then held the head of the screw firmly on top of the hot bolt, adding heat to the bolt from below to keep the temperature very high. I used release agent again, then heated again before attempting to undo it, and it worked. Standard 6mm socket screws with large hex recesses have gone back in, with a twist of PTFE plumbers tape to keep steel and alloy apart as thread bonding is often due to galvanic action.

[Flyingdog]

With a carb (even when fully purged of fuel) you do not want to warp it by using a blowlamp, but I needed to try thermal shock. I found a very large 3/4 inch bolt and put it in the vice, heated its end to cherry red with a high heat gas torch, and then held the head of the screw firmly on top of the hot bolt, adding heat to the bolt from below to keep the temperature very high. I used release agent again, then heated again before attempting to undo it, and it worked. Standard 6mm socket screws with large hex recesses have gone back in, with a twist of PTFE plumbers tape to keep steel and alloy apart as thread bonding is often due to galvanic action.

Saw the same thing on The Big Bang Theory. I also found those little screws have no chance against a soldering gun, liquid wrench and impact driver, if they wanted to be stubborn. Why one should also replace those fasteners with allen heads. Stainless if you find them.