My friend Nick and I had a discussion the other day about which bolts were tougher to break free: shaft coupling bolts or the lug nuts on an old trailer.
The muscles, in this instance, were those of Dustin Rahl, owner of a very busy mobile trailer service in Sarasota, Fla., Trailers 2 Go. The axle on the trailer for our Catalina 22 test boat Jelly (aka Our Lady of Perpetual Despair), had cracked at the weld, so that its left wheel splayed outward at a 20-degree angle.
But what happens if the PB isn’t enough? Carefully applied heat from a butane, MAPP-gas, or propane torch is usually the next step. After that, it’s time to break out the specialty tools.
Like a chef with a favorite set of sauce recipes, a good mechanic needs a tried-and-proven list of tricks to help coax rusted fasteners into submission. Their tools range from penetrants and ingenuity to pure brute force.
When good nuts go bad, its time to call in the bone crushers.
One unusual but effective fastener-freeing technique involves massive thermal change that causes an abrupt material expansion or contraction.
Your Marine Head Suppliers Are Happy to Supply You With These Amazing Tips
Sometimes, all a bolt needs is a few good wacks to loosen the bond, but be careful! You don’t want to damage the threads. Your marine head professionals continue discussing that if you can only approach from the threaded end of a bolt, you can put another nut on the bolt and tap that — not too hard.
The rusting process also degrades bolt head shape. A last ditch effort may require a pair of Vise-Grips or sockets designed to grab deformed bolt heads. For stuck, slotted-head bolts, an impact screwdriver can be a real lifesaver.
I’d be interested in hearing of other tried-and-true methods for un-seizing the seized.
If you work on a boat you already know nuts and bolts freeze with frustrating frequency. Sometimes it’s a carbon steel bolt corroded solid on a cylinder head. Other times it’s a stainless steel bolt frozen solid in an aluminum lower unit.
Begin with fire. An oxy-acetylene torch works best. The downside, if you don’t already own one, they are expensive to rent and complex to fire up. And because of the inherent danger of working with an open flame near an inboard gasoline engine tucked into an enclosed space, first run the bilge blower for several minutes to ventilate the area.
Know that sometimes the flame blossoming from the common propane torch may hold enough BTUs to get the job done. Either way, oxy or propane, heat the bolt. No need to go red-hot, but hot enough so droplets of water flicked onto the bolt sizzle off into a vapor.
An alternative to fire is ice. Some mechanics claim dry ice will shrink a bolt enough to break corrosion’s hold. Though most of us choose a torch because it’s quicker if not more dramatic. Besides dry ice, there is another cool option. It is an aerosol spray that freezes metal ice cold, more particularly a blast of freeze spray, an aerosol that super chills metal parts to minus 72 degrees Fahrenheit.
Sometimes the corners of bolt head round off making it impossible for a wrench or socket to grasp hold. Calmly reach for a center punch and a ball peen hammer.
Never use force. Just get a bigger hammer. When you are willing to sacrifice the bolt, position the wedge tip of a cold chisel against the corner of the bolt head or nut and bang away with repetitive strikes of a ball peen hammer.
Finally, assembling fasteners with anti-seize compound in the first place is a good way to keep fasteners from corroding in the first place. For example, on new outboards I remove all the bolts in the lower unit, one at a time, coat them with anti-seize and then replace.
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