Can't loosen screw to change oil on sd-20 saildrive.

[jbinbi]

Boat is hauled for the winter. I want to change the saildrive oil. Unfortunately, this is a flat head screw that is probably close to 12mm in diameter. The flat head drivers I have are maybe half that at best. Tried turning, tried turning with a vice grips, can't move it at all.

Anyone have tricks for loosening this screw? Don't want to use heat.

This should not be a flat head screw!

[J.Kitchens]

You need a drag link bit and a ratchet.

[jbinbi]

Thanks. Just googled this. That probably will do the trick, just need to find the right thickness that will fit in the screw head. With a thousand tools on my boat and basement, I did not know of this product.

[Wotname]

Originally Posted by jbinbi

...........
Anyone have tricks for loosening this screw? Don't want to use heat.
........

Also try tightening it a tiny bit (a couple of degrees only). This often breaks the corrosion seal and usually the faces of the screw aren't damaged in the CW direction.

[Lepke]

A lot of hand power tools have a impact function. It works well for breaking loose screws w/o damaging the head.
Hammer impact wrench is a cheap way. About $20 on ebay. I use to use one on a motorcycle case.

[motion30]

Impact driver as Lepke suggested

[ferrailleur]

Originally Posted by Lepke

A lot of hand power tools have a impact function. It works well for breaking loose screws w/o damaging the head.
Hammer impact wrench is a cheap way. About $20 on ebay. I use to use one on a motorcycle case.

Excellent tool to have onboard..... I used it to free an outhaul slider on my boom (frozen stainless hex bolt in aluminum boom)

[out42]

Had the same problem and as everyone suggests, an impact screwdriver will do the trick. Although the leg is alloy, it won't be harmed as it's rubber-mounted.

[KeelMe]

An impact driver as recommended above is a wonderful tool but it does not replace the fact that you should properly size a screwdriver to fill the slot in the screw head. The widest bit I have seen for an impact driver is roughly 10mm wide and 1mm thick. This will not fill the slot in the screw head.

Use a properly sized drag link bit.

[hellosailor]

Another vote for Lepke.

But when you get the screw out? Maybe take it to a NAPA store or other good parts source, and see if you can get a simple hex-head bolt with matching threads. Do the upgrade.

[KeelMe]

It's not a screw it's a drain plug.

[Emptynest]

I used breakaway spray & let it soak in for a day that’s what worked for me

[Hesti]

Through the above mentioned bit or a fitting (big) screwdriver, giving it a whack with a hammer while applying torque with the bit or the fitting screwdriver may also work. To much of a whack and it can damage the casting though. But when lacking an impact screwdriver, it is an alternative worth trying.


Heat can also help, if you have a heatgun.

[Dooglas]

Purchase a large screwdriver that comes closer to fitting the slot. Craftsman makes large screwdrivers of that sort which have square shafts. That allows you to fit a wrench to the shaft and apply considerably more pressure to a better fitting bit. That will likely spell success.

[akprb]

My guy in Whangarai, Russ, just drained the oil by removing the whole shaft seal as he also replaced the O rings each haul out :-) That works to and ya get those never ending leaking seals done at the same time.