3M 4200 will work, but why not drill out the holes over-size, full in with marine-tex, and re-drill?
Now you have covered any bare wood, and have no worries.
Go ahead and coat the bolt with 4200...... when it is pushed through the hole (and if the hole is the right diameter) and as it it pushed through is when it collects the sealant at the head of the bolt..... when you install the washer and nut put some sealant on the washer.
Just be very careful when bolting through a transom. Most of the bolts used are fine thread stainless steel and if you "bull" them they will crush, deform and run the risk of ripping through a transom.
Thanks. Heres the issue though....The lower engine mount bolts go through the bracket on the engine (outboard), and since this bracket is slotted it seems rather difficult to seal...Any ideas?
The procedure mentioned will work. Just a little rotation while you're feeding the bolt through helps spread the sealant around. Also, if you counter-sink the holes a little you'll get better sealant build-up around the edges.
Drilling the hole 1/16 to 1/8 larger and filling with thickened resin, then drilling the proper sized hole is the best way.
But if you properly seal it as others have described you'll be perfectly fine. I also like to put a thick bead of 4000 UV on the entire transom bracket before installation. When you install the engine and tighten the mounting bolts the excess 4000 will ooze out with which you can make a nice smooth fillet with your finger.
THe problem is I have the motor on already, just have the bottom bolts removed. I put sealant on the bolt, and filled the slot with sealant....I purposely put no sealant on the inside of the transom so I could see if it was leaking. I took to the lake and found that it WAS leaking so Im going to do the oversize trick as I dont want to constantly wonder if my transom is getting soaked again...
Can I drill oversize and fill with epoxy filler (purchased from rot doctor) then drill to size?? Do I need anything special other than a drill and a bit to drill these holes??
