Trim tab removal on a 1970s(?) Merc 500 Thunderbolt 50hp

[Blake013]

Hi there, can anyone advise how I remove the trim tab to get the lower unit off this engine?

There is a small hole above it which is just large enough to get a thin 5/16 socket in but I am not sure if there is a bolt or Allan key inside it.

Picture of engine and bolt I am referring to attached.

Thanks for reading!

 

[roscoe]

It’s an allen head.

 

[Blake013]

It’s an allen head.

Thank you! Will keep trying with Alan keys then. There was some decay in there so hoping it isn’t rusted out as can’t seem to find the head and can’t get a good look inside.

 

[racerone]

Flashlight helps.

 

[Scott Danforth]

Worse case, drill head of bolt off then pull lower and replace bolt

 

[Blake013]

I couldn’t see inside so I ended up drilling a small hole on the side so I could blow all the gunk out. This then exposed a rusted head so looks like I’ll be drilling it…

Thank you all

 

[Chris1956]

Crap, the zinc is much softer. Destroy the zinc anode and replace the bolt. Drill a few holes in the zinc and break it off with a chistle.

Older Mercs often had hex head bolts there. Sometimes you needed a specific thin wall 3/8" drive socket to get to 'em. The right size socket would just fit in the hole.

 

[1960 Starflite]

My 1965 (65) hp was like yours. I ground the six sides of a 3/8" Allen until I could drive it into socket. I still have the wrench for special occasions.

 

[Blake013]

Crap, the zinc is much softer. Destroy the zinc anode and replace the bolt. Drill a few holes in the zinc and break it off with a chistle.

Older Mercs often had hex head bolts there. Sometimes you needed a specific thin wall 3/8" drive socket to get to 'em. The right size socket would just fit in the hole.

Thank you, yes, will cut from the back and then try and cut it or chisel it. Hopefully it breaks off easily!