Outboard Motor screw clamps stuck due to corrosion.

[RxBoat]

My 1976 Evinrude 6 hp outboard motor screw clamps were completely immovable, corroded by salt water.
I was able to get one of them unstuck by soaking in CLR 50% solution for 5 days. (See photos)
Now working on the 2nd one using WD-40's Specialty Penetrant. Will see how that does.

 

[jakedaawg]

Pretty ingenious soaking method. Like it.

If you were to drive out the pin that holds the handle part of the screw on you might be able to figure a way to put an impact on the screw.

 

[racerone]

Cut it off.---Drill it ( 3/8" ) to allow it to collapse / ease the pressure and try and turn it out.

 

[Scott Danforth]

Pick up a can of kroil vs the wd-40

 

[jrttoday]

haven't tried it personally, but am hearing rave reviews about PB Blaster - think that's what it's called and available at autozone. The drastic measure? would be to apply heat w/propane torch, just not cherry red!!!

 

[StarTed]

I've had pretty good luck using a propane torch concentrating the heat on the part with female threads and cooling the male threads as much as possible. Dry ice could be a big help on the clamp's threads. A few cycles may be needed. Don't overdo the heating as stated above. Repeating a few times usually does it.

 

[racerone]

?????---Aluminum does NOT go cherry red !!

 

[F_R]

After spending half my life repairing salt water motors, I gotta say you were lucky to get the one out by soaking. Usually, those things are hopeless. My method in such cases is to drill it out, purposely drilling it off center till one side of the hole touches the threads. What you have left is a C-shaped piece that can be turned out because one side is missing. Heat alone is virtually worthless because both parts are aluminum and expand at the same rate. Add dry ice? Interesting, never tried that (nor had any).

 

[jrttoday]

racerone you are correct! it's been a ton of years since I've seen heat applied on outboards to get bolts out. Most of my bolt extraction has been on heavy equipment - undercarriages and such. The dry ice, maybe; used to weld a nut to whatever was left of the bolt and drip water into the nut while still hot. Then spin it out w/ratchet.
And propane won't heat like acetylene anyway.... guess I was just being graphic to advise caution. You can destroy metal with too much heat

PS: heating and rapidly cooling WILL affect strength of the clamp; may be stronger, maybe weaker as it may be brittle? I would heat it and let it cool naturally

 

[StarTed]

I try not to cool the external threads because I want them to remain expanded while I try to rapidly cool the internal threads. Sometimes that works and sometimes it doesn't. Drilling it out is the last act that I hesitate to do because it seems to me that the softer metal tends to attract the drill leaving a less then ideal thread left. If the parts won't separate then both pieces will need to be replaced anyway so you only loose time which is very important to a business but not so much to us back home mechanics.

Good luck with your frozen parts.

 

[racerone]

Rx has made no more posts , I assume the problem has been solved here.----And as stated both parts are aluminum so heating will not help much.--Drilling is the way to proceed on this and will reduce the chance of damage to the bracket !!