Hello, I need to put new sheaves on the deck of my boat. One of the bolts unscrews but the other does not. I tried a bolt loosening product plus electric drill plus tapping with hammer but it still is stuck. Does anyone have a good method to loosen the sheave bolt? Pic attached.
Seized Halyard Deck Sheave Bolt
- Thread starter QCI
- Start date
Penatrating oil, patience and then more penatrating oil. These sort of things can take a few days. An impact screwdriver (the kind you whack with a hammer) will help you to not strip that screw head any further.... something like this...
At some point you may find the head of the screw is stripped and you can then cut a slot with a hacksaw and use a flat head screw driver (until you strip that one
)
If you strip that one also, then you need to tap and drill out the screw and use one of the corkscrew bits seen in the first photo. you wind those into the hole you drilled and then it grips the metal and you can back out the screw with a power drill. You might also try (be very careful) to touch the head of that screw with a propane torch.
At some point you may find the head of the screw is stripped and you can then cut a slot with a hacksaw and use a flat head screw driver (until you strip that one
)If you strip that one also, then you need to tap and drill out the screw and use one of the corkscrew bits seen in the first photo. you wind those into the hole you drilled and then it grips the metal and you can back out the screw with a power drill. You might also try (be very careful) to touch the head of that screw with a propane torch.
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The best results that I have had for loosening small fasteners like yours is to use penetrating oil. I normally use PB Blaster, but there are others. The first problem you have is getting the oil into the threads below the assembly. Using a tube on the spray nozzle can help. You might want to remove the lines first so that they don't get soaked with the oil.
Tapping down on the head of the bolt can also help by encouraging the oil to penetrate.
But the real trick is to use a small impact driver like the 18V Ryobi tool. They turn and pound at the same time. A plain old electric drill will just strip the heads. It is this shock plus torque in concert with the oil that is most effective. And the bonus is that with limited torque the heads are much less likely to strip. I have twisted the head off of bolts and then using a impact driver on a similar bolt having it backed out without breaking.
YMMV, of course.
Those screws are stainless and they are likely threaded into an aluminum plate that is glassed into the structure. Aluminum and stainless don't play well together, hence the corrosion and jammed up threads.
And once you get the bolts out, re-install with Tel-Gel or some other anti-seizing compound to avoid future difficulties.
Tapping down on the head of the bolt can also help by encouraging the oil to penetrate.
But the real trick is to use a small impact driver like the 18V Ryobi tool. They turn and pound at the same time. A plain old electric drill will just strip the heads. It is this shock plus torque in concert with the oil that is most effective. And the bonus is that with limited torque the heads are much less likely to strip. I have twisted the head off of bolts and then using a impact driver on a similar bolt having it backed out without breaking.
YMMV, of course.
Those screws are stainless and they are likely threaded into an aluminum plate that is glassed into the structure. Aluminum and stainless don't play well together, hence the corrosion and jammed up threads.
And once you get the bolts out, re-install with Tel-Gel or some other anti-seizing compound to avoid future difficulties.
Another consideration: If you grind the head of the screw off, the sheaves and plate will come up and off, leaving the bolt sticking up alone ..then you can apply heat to the bolt alone and grab it with vice grip pliers. With some pen oil where it enters the deck, you could VERY Carefully rotate the bolt back and forth being careful that ya don't put side loads on the bolt .. It should unscrew from the embedded aluminum plate. First, try an impact driver.., something like this:
6 Bit Impact Screwdriver Set With Case (harborfreight.com)
6 Bit Impact Screwdriver Set With Case (harborfreight.com)
It is easy to give advice on patience... an entirely different beast when applying it myself.
I think this is the one idea that gets right to the crux of the matter. The bolt is screwed into an embedded aluminum plate in the deck. That is how Hunter affixed everything to the deck. Good idea but absolute hell if you want to change anything. THAT is where the corrosion is occurring. THAT is where the SS bolt to aluminum bond is located. THAT is where the penetrating fluid has to reach.
STOP twisting and banging, and torquing on the top of the bolt. You stand a good chance of breaking off the bolt right at the deck level. Get down to the deck level first and wiggle, apply penetrant, apply heat, apply anything else you can dream of to breal the bond. Break the bolt off at the deck and then the fun REALLY begins.
If the bolt head is still fairly undamaged you could try drilling the head off by using a bit just slightly larger than the diameter of the bolt body, similar to removing the head off a rivet. Grinding may mar the surface of the organizer. As others have said you’re likely facing corrosion due to dissimilar metals that penetrating fluid will not really help with. Alternating heat/cooling and occasional impacts may help to get it free. Take it slow! While you can drill out and use a helicoil or larger diameter bolt after removal, drilling the existing stainless bolt out of the embedded backing plate can be quite challenging.
Whether you are using a screwdriver or impact, you want to use 90% of your strength to push the tool into the head of the fastener and 10% to turn it to prevent it from slipping. This is why the impact tool that @rgranger suggested works well. I've also done the tactic I mentioned with a plain screwdriver as well as electric impact wrenches. If all else fails, applying heat works. There's also cans at the automotive store that will freeze the bolt but I haven't tried them
Now that's something worth trying as you really want to shrink the diameter of the bolt by rapid cooling. Have not heard of this before.
From the label, it looks like extreme caution is required when using this product.
I purchased the manual impact wrench. I will try it this weekend. I really appreciate all of the advise on this matter!
Some days ya can't win for trying
.As you say, with the coeff. of exp. for aluminum being greater than that of SS, then the procedure would be to S-L-O-W-L-Y heat the bolt and buried aluminum plate together and then try to unscrew the unholy mess. Only doable on a hot day in August.
Once had to remove a forward cleat on the toe rail and wound up destroying the two holes in the alum. plate. SS bolts came out with a few kinks as well. By a one in a billion chance, was able to get under this particular cleat and install backing nuts on the new bolts. Could not have gotten within a mile of the other five cleats to install backing nuts. Buried alum. plates are a good idea, unless you have to remove the bolts somewhere down the line and then they are a terrible idea.
I think the main idea is to break the bond which is most likely to happen when the two fasteners expand/contract at different rates