Broken Thumb Screw Removal

[Aidan Smith]

Hello! Working on a 1960 Evinrude Yachtwin/Lightwin, and I was attempting to un-seize the clamp screws, but ultimately failed.

Would anyone have any recommendations of how to remove it?

The rest of the motor is in great shape, other than it is missing the float bowl, if anyone has one.

 

Thanks!

"Shells sink, dreams float. Life's good on our boat."
1931 Johnson A-50
1950 Mercury KF-7
1951 Mercury KG-7
1956 Johnson JW-12R

[seakaye12]

Is there enough at the back to get a hefty vice-grip pliers on it?

The trick to getting those out is HEAT.  Lots of heat .  The HEAT and QUENCH techniques.  Don’t even try without heat;  if you do get the screw to move it might damage the threads.

In your situation…..if the heat and vice-grips is not the answer….then you have to drill it out.  I might be looking for another clamp if it’s a common motor.

1 user thanked author for this post.

Aidan Smith

[Aidan Smith]

Thanks,

I believe there is enough at the back I can get some vice grips on it, and try with heat.

I’d like to keep this whole motor intact and original, as it is a low serial number and has been in our family for a long time.

It is an early Yachtwin, the 3 hp but with a 90 degree lower instead.

Any solvent ideas for breaking it loose?

 

"Shells sink, dreams float. Life's good on our boat."
1931 Johnson A-50
1950 Mercury KF-7
1951 Mercury KG-7
1956 Johnson JW-12R

[crosbyman]

you could try to heat up the  bolt and  soak it with a release agent (WD40 and similar)   try to rotate both ways  and  resoak   ..repeat

takes patience

drilling with  gradually increasing drill sizes  will eventutally weaken  it but don’t  drill out the threads !

you can also try  extra cold  from a simple  Dollar store keyboard  spray can inverted.   the stuff will freeze  quickly and may break the bond.

Joining AOMCI has priviledges 🙂

[fleetwin]

You will need more heat than the standard propane torch, get the mapp gas torch.  Patience is the key to success, and not burning yourself.  You might consider removing that side of the stern bracket so you can clamp in a a big vise.  Having an assistant helps as well.  Let the assistant apply the heat while you apply pressure to the vise grip, hoping for even the slightest movement of the snapped screw.  Once it moves slightly, let it cool, then repeat the process until it moves some more.  In this case you have that nice little valley between the bracket and screw to add oil.  Be careful with the heat near the thin part of the casting, don’t melt it.

2 users thanked author for this post.

Aidan Smith, seakaye12

[wedgie]

Drill into side of the bracket to the depth of the threads. 1/8 bit or what have you.  Inject with acetone and transmission fluid mix. let sit overnight and try heating . Twist out from the back if there’s more to grab on to.

[fleetwin]

wedgie wrote:

Drill into side of the bracket to the depth of the threads. 1/8 bit or what have you.  Inject with acetone and transmission fluid mix. let sit overnight and try heating . Twist out from the back if there’s more to grab on to.

Great plan!

[Sam M.]

I would almost be tempted to drill a hole in it, tap it, and insert a strong (grade 8?) bolt or rod that you can put a lot of leverage on.  Then, after a lot of soaking with penetrant, try to twist it out.  If the penetrant has not seeped through the threads from one side to the other, put more on until it seeps through before trying to twist it out.  That would be my suggestion.

[Author]

Posts