Can I apply heat to head bolt? Johnson RDE-17 1955 25 hp

[outboardnut]

The cylinder head is still on the block.
If I apply heat to the offending bolt and surrounding area will I warp the cylinder head?
I would be using propane.

[crosbyman]

have you tried torquing it in …. just a bit then out

I use an impact screwdriver with a socket …. not those big 1/2 inch nut drivers but that is up to you !

as to heat i’ll let the pros decide

Joining AOMCI has priviledges 🙂

[Buccaneer]

I think if I used heat, via a torch, I’d keep a small flame tip
just on the bolt head for a while, spray a little penetrate
off and on, maybe smack the bolt head with a hammer
a few times, and keep trying to turn the bolt back and forth
a little.
That said, I have bad memories or snapping off 5 of the ten
bolts on a Johnson, and then trying to remove them.
Good Luck, and have patience!

Prepare to be boarded!

[frankr]

My 2c, I have removed many thousands of such bolts. And, admittedly, busted off a few also. My take on the subject is that most people are far too timid, and afraid of damaging something.

But nevertheless, I use heat. HOT heat, like from an acetylene torch. Propane usually is not hot enough. Heat the aluminum around the bolt, not the bolt. That expands the aluminum, loosening it’s grip on the steel bolt. While it is very hot, but short of melting, quickly remove the bolt (yes with air wrench).

Warp the head??? Not to fret, you were going to clean it up and resurface it anyway—weren’t you?

Good luck.

[bobw]

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
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“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."

• This reply was modified 5 years, 5 months ago by bobw.

[outboardnut]

Yes I was going to resurface the head (figure eight motion-sand paper on sheet of glass)
What type of grit should I use?
Time to heat it up

[bob-d]

Just saw a test of penetrants on YouTube, and Deep Creep by Seafoam came in first, and actually penetrated rusty bolts. Bought a can to give it a try.
I also agree with Frank and heat the hell out of the surrounding surface first. I use the yellow can mapp gas which works for me. Just did a 55 15 HP Evinrude and didn’t snap 1 head bolt!
Bob D

[fleetwin]

Like Frank says, the propane torch isn’t gonna cut it….Trying to rock the bolt using only the propane will probably snap it off….You will need to find a bigger acetylene torch for this job…
One more idea…..Are all the head bolts out except for the one frozen one? If so,, try tapping on the head (with a heavy plastic mallet) in the direction of loosening the bolt. Like others have said, oftentimes the bolt corrodes to the head where no threads are present. If the head and bolt move together, you will know that the shank of the bolt is corroded to the head.. If so, reheat the head and try rocking it back and forth with the mallet until it loses its grip on the bolt…

• This reply was modified 5 years, 5 months ago by fleetwin.

[bobw]

Frank and Fleetwin are right with regard to use of an acetylene torch if you have access to one and know how to use it without melting the block. I only have a propane torch and it’s easy to wring a bolt off if you’re not careful. I’ve twisted off a few in the past when trying to rush things. That’s why I take it slow and easy laying on the wrench after using just the propane and that’s why it took me a week to get the head bolts out of that ’72 Evinrude. As corroded as a lot of the bolts were on that motor, I’m still convinced propane will work with lots of penetrating oil but it sure takes a lot longer. Then there’s always the discussion about the best penetrating fluid.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“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."

[fleetwin]

Well, there is one thing we all agree on, slow and steady is the only way to go…. Rush it, overheat/melt, force the bolt, and game over….

[Author]

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