More Boat Tips: Unsticking Stuck Nuts and Bolts

Posted by Darrell Nicholson at 05:36AM - Comments: (17)

Dustin Rahl attacks Jelly's trailer with two squirts of PB.

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. Nick pointed out that lug nuts spend more time underwater and are usually torqued down a whole lot tighter than a shaft coupling screw. On the opposite side, I argued that shaft coupling bolts require you to assume the yoga pose “Downward Pretzel” just to see the bolts. The argument was never settled, but this week, I was reminded that even the most stubborn bolts can often be coaxed loose with a judicious application of penetrating oil and some muscle.      

PB Blaster

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. Dustin arrived early Tuesday to remove the axle, which was rusted beyond hope, so that he could measure it and order a new one. Alas, the lug nut bolts stood in his way.

He didn’t even bother to try them cold. “I’ll just give it a shot of PB Blaster,” he said.

We've tested spray petroleum products to a fare-thee-well. Some are good for loosening bolts, others for sealing electrical connections, and others for protecting against corrosion. When it comes to loosening bolts, we’ve found the PB Blaster works best. That’s not to say the others won’t work. It’s just that when it comes to the really tough bolts, PB rises to the top.

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. A breaker bar for sockets and the learned wisdom of just the right amount of torque works much of the time. For really stubborn fasteners, there are nut cutters, and a wide range of torque- and shock-inducing gadgets.

Ralph Naranjo
Ralph Naranjo

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. A piece of dry ice is pressed against a stubborn bolt head to shrink its dimensions. This results in the disruption of the rusty bond and more willingness for the bolt to turn.

Less esoteric solutions include box or socket wrenches with fewer facets, which afford a tighter grip on a nut or bolt head and allow more torque without stripping the hardware. The better your ability to apply force, the more careful you must be to avoid breaking the fastener.

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. 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. Alternately, you can use a rubberized mallet, or a piece of hardwood to insulate the bolt from the hammer.

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.

Frozen, rusted nuts present a similar problem, but there are tools that allow you to split the nut without destroying the bolt. Nut crackers use a chisel-like edge that is screw-pressed against the side of a nut. Once the tool is tightened, a machinist’s hammer is used to smack the tool, and its blade splits the nut.

I’d be interested in hearing of other tried-and-true methods for un-seizing the seized.

Comments (15)

I have used most of thw products mentioned though on old farm machinery. I personally favor Aero-Kroil then Nut buster( I do not believe it is now available) and then PB blaster. I read a semi scientific evaluation (you can only break a nut free once) which found a 50:50 mixture of acetone and ATF far superior. Acetone is difficult to keep in a dispenser. Eventually I settled on the judicious use of time . Cover the bolt with ATF and come back tomorrow. Possibly repeat and maybe again. I think it is better than all the spray cans. Remember if it really won't move that heavily marking (trying to split the nut) with a cold chisel is an effective last ditch maneuver.

Posted by: caryandras | January 18, 2017 7:36 PM    Report this comment

Someone else posted this below, but I want to emphasize that cracking the nut tighter will frequently allow it to be loosened when any amount of force will not allow it to loosen it otherwise. I read all the comments carefully. At one time or another I've tried them all but the "weld the race" and the "mini-doctor 2 induction heater". Good luck to all the readers of these posts!

Posted by: Annapolis Sailor | January 18, 2017 10:49 AM    Report this comment

ollive oil with a dash of balsamic vinegar on some arugula with parmesan cheese. eat slowly while waiting for PB blaster to work magic

Posted by: badornato | January 18, 2017 10:16 AM    Report this comment

"Mini-doctor" won't work on non-magnetic stainless steels, which greatly limits its value for boat work.

Posted by: ROBERT D | March 5, 2013 8:44 AM    Report this comment

As mentioned by one of the respondants, use any size wrench that fits. Removing old exhaust manifold bolts in a northern vehicle that has seen plenty of salt proves that the bolts sizes were not the same as when they left the factory. What started out as an SAE is considerably smaller and now a Metric!!! Find the multifaceted (12point) wrench or socket that is just barely to small and beat it on with a hammer. Now there's a nice tight fit without any slop. Don't laugh it works!!! And finally, when all else fails and your stuck holding the bolt head in one hand and scratching your head with the other... Craftsman (and others I'm sure) make a straight fluke Easy Out that is hands down easier to use than the typical spiral easy outs normally seen for sale and if memory serves me correct they weren't much more expensive.

Posted by: | February 1, 2013 12:25 PM    Report this comment

I had to loosen some motor mount bolts on my sail boat. They were the ones used to align the engine. I finally had to resort to using the cold chisel to expand the nut. My favorite is the oxy-acetylene cutting torch. Worked in a junkyard as a kid...

Posted by: Raymond S | January 22, 2013 9:18 PM    Report this comment

PB Blaster is great I used it to help free the frozen piston rings on a 427 cc engine. Back to rusted nuts and bolts I always tighten slightly before I loosen,
if it wont come off then I use PB.
Try it you will like it.

Posted by: Unknown | January 17, 2013 12:59 AM    Report this comment

I agree with the 50/50 Trans fluid and acetone. PB Blaster has worked for me better than Aero-Kroil and is my second choice.

Posted by: BRIAN S | January 16, 2013 8:12 PM    Report this comment

I have drilled small holes in a nut's flat down to the stud's threads in order to introduce the Liquid Wrench or PB Blaster where it counts; directly to the threads.

Posted by: HERMAN S | January 16, 2013 6:52 PM    Report this comment

A pneumatic impact wrench can be very helpful. Keep the power turned down and use the vibration to help oil penetrate. A tight fit with the tool is important, six point sockets are great, and don't worry about whether it's english, metric or British standard, just find the one that fits tightest. For slotted fasteners you may need to file down an oversized screwdriver until it just fits, for stripped Phillips fasteners you may need to cut a slot. Occasionally an "easy out" screw remover will work if it doesn't break off in the hole and make the problem worse. If you can get hardened fasteners super cold and then smack them between two hammers they will shatter.

The best trick I've seen, though, is for removing frozen bearing races. Weld a bead on the inner face. When it cools the race will likely fall out on its own.


Dave Kallgren

Posted by: DAVID K | January 16, 2013 11:19 AM    Report this comment

many tests in the gearhead world of old car restoration agree: a much more effective penetrant than PB Blaster is a 50/50 mixture of Dexron type transmission fluid and acetone. I would not carry acetone on board because of flamability. Who knows what is in PB Balster? It may be acetone. Ignore myths about WD40; it is mostly kerosene, does not contain fish oil and is as toxic as all the others. Dick Warren

Posted by: Richard W | January 16, 2013 11:15 AM    Report this comment

And Auto Transmission fluid with either Acetone or Methyl Ethyl Ketone?

Posted by: JONATHAN K | January 16, 2013 10:34 AM    Report this comment

I have nothing in particular to add, except that the "Mini Ductor 2" that Phantomracer mentions in his comment is the coolest thing I've seen in a while.

Posted by: JFolkers | January 15, 2013 6:01 PM    Report this comment

An expensive, but VERY effective way is to use induction. After using it at an autobody class to remove some stubborn bolts, I had to own it! The "Mini-doctor 2" heats nuts or bolts up in a few seconds (2-20 seconds) and makes them so easy to remove! Far safer than an open torch, can be used near plastic! Less messy and far faster than penetrating oils.

I was crazy enough to buy one, as I am in the middle of restoring my MGB-GT. I know few people would spend the money ($450-500) for this tool, but it is, hand down, the most effective, fastest, and safest rust busting tool I have used. watch the videos on their site, and there are some on youtube, it does work that easily and fast!

It also helps save expensive fasteners that might be otherwise destroyed by other impact/cutting methods.

It is beyond the scope of the average backyard mechanic, but I had to mention it, as it is new to me and has a cool factor!

Posted by: Phantomracer | January 15, 2013 5:17 PM    Report this comment

I work for an amphibious vehicle tour company. Our mechanics often are confronted with nuts and bolts there since WWII. Years ago as part of a big "going green" effort, our company made a move towards using environmentally friendly products. One of the biggest surprises of this effort was a product called "Zep 70". By all of the mechanics, and my experiences, it works better that PB Blaster.

Posted by: Chris Makridis | January 15, 2013 4:34 PM    Report this comment

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