As Buccaneer noted, patience is the name of the game here. My 1972 Evinrude was a salt water motor and it took me the better part of a week to get all 10 head bolts out. Enclosed pic shows how rough these head bolts looked. I had the best luck with the following process using a propane torch:
– As Buc noted, heat the head of the bolt first, rap the head of the bolt, then apply a good penetrating oil and walk away for awhile.
– Heat the area of the block where the bolt threads into the block. I’m not afraid to apply lots of heat here.
– Heat the area of the cylinder head where the bolt passes through it
– While still hot, apply copious amounts of penetrating oil around the bolt head. Be careful as the oil can ignite on you.
– Only after applying the heat and the penetrating oil, try to tighten the bolt just a bit before trying to back it out,
– If the bolt starts to move, just rock it back and forth a little bit at a time. This is not the time to get greedy and back it out all at once. Keep applying heat and oil.
Many times, the bolt is frozen not just by the threaded part of the bolt but by the unthreaded portion of the bolt right under the bolt head where it passes through the cylinder head.
I had 7 of the 10 head bolts that backed out pretty quickly with this approach. Two more came out after a full day of alternating heating and cooling while using lots of penetrating. oil. The last bolt took 3 more days to get it out. I finally got it to budge by using my impact gun on it’s lowest setting, just slowly hammering away back and forth until it finally backed out about 1/8 of a turn. I then went back to the torch, lots of heat and a socket wrench to get it out.
I know I applied tons of heat from the torch to get these head bolts out and it did not warp the cylinder head.
PATIENCE is the key, slow and easy does it – if it won’t move, don’t force it. Just walk away for awhile (or a day or two) and keep applying heat and oil. Also found it best to use a 6-sided socket wrench rather than a 12-point box end wrench to avoid rounding off the bolt head.
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20
1982 Evinrude 25hp
“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."
