Drilling out siezed bolts

[Brian]

What kind of drill bits, HSS, carbide, etc.... is going to have the best chance of drilling out snapped off, siezed up bolts from an outboard engine?

Got a couple of Chrysler motors I'm trying to make one good one out of. I've read up on the heat and penetrating oil methods but I'm expecting I might have to drill at least one of them out.

My boat? '59 Clippercraft, 17' cruiser. As soon as I figure out how to post images, I'll upload some pic's of the old girl.

thanks

[Tim McCrain]

Brian, welcome to the forum!

The method I found that worked for me was to use a Dremel with a tungsten carbide straight bit. I drilled a small hole in the center of the bolt, just a little larger than the bit, and then slowly circled the outside of the hole with the dremel, enlarging and deepening the hole gradually. This gives a lot of control and eliminates the problem of trying to stay centered in the bolt. After doing a couple of them I found that I could clean the bolt out leaving just the threads in the hole, and then pick them out with a sharp machinist's scribe. I had so many to do that I got way better at this than I ever wanted to!

[Tim_Mattson]

Seized bolts

Brian,
The drill bits meant for SS that work best for me have the shiny finish and a very sharp point.Watch out for some that are the pilot point which can hog out more than you need the first hole.
The Black Carbide do work well too ,but try drilling a broken one out.
Before breaking them, soak with Tri-flow or Fluid Film(from Fisheries in Sea.) and then hit it with another flavor that can be runnier or thinner....Aero-Kroil ,Freeze-Off or your favorite flavor(NOT WD-40,which is pure solvant,good for trailers you are disposing of once apart,or on fish lures,bait).
The oily stuff preserves paint ,rubber and decals from getting too wasted while heating and gives you a telltale of when things are ready to turn,say a puff of smoke or any bubbling seen at the threads of the stuck bolt.
Turn while still heating,if it tightens as it turns ,wait for the heat to catch up as the backside of a bolt can be cold.
The thick Lanolin is waxy and will hold the runny stuff at the desired bolt you are targeting.After a day or THREE of soaking,then start using heat from a yellow Mapp gas bottle,trying NOT to heat the bolt itself.
If a bunch of bolts are tight,start in an area where you can follow the heat to the next one or two.
Work the hardest ones first,check the others as they can loosen while working near them.
Parts motors you don`t care much about are best to practice on first,then work to the good one.
Being able to roll it so the bolt threads are below the head will get the pentrant going where it will matter.
Use a 1/4`` drive ratchet,(and only a few fingers at first)unless the bolt is bigger,hex drive sockets are a must,and use a hand impact driver after marking a line so you can see if they budge while tapping.
I`ve learned to not drill them out until trying to remove the head first,then try gripping it with vice grips after the head or water cover is removed,thus allowing direct application of the pentrant.
Heat and Cool,Heat and cool,then Heat and hopefully turn.

I have an engine/Tilt assy on my bench that has seen 3 -4 weeks of this stuff.

If you do get to drill ,do an 1/8`` pilot hole ,then work up until you get close to threads on one side,or hopefully you are dead center.A sharp center punch can help center the hole.Flatten it and start over if off center.
Use cutting oil or lube while tapping,use GOOD Taps,made in USA (or West GERMANY) and watch for slivers!
Goodluck,
Tim M

[Brian]

Ok, that sounds like a plan for the hard cases. I just needed a doomsday back-up method. As tempting as EZ-out's are, I've learned that lesson.

Got 70 and 75 hp Chryslers. The one I'm hoping to get running is the 75 I just got cheap. When the guy said the bottom cylinder was bad, I was thinking "yeah." But tearing into it, he was right. The piston was burnt and blowing by. Hopefully, that's all.

[Brian]

Other Tim, appreciate the heads up on the solvents and strategies. Currently there are 5 with protruding shafts and 1 broke off flush.

This'll be a weeks long project getting the block out and apart, but if I can get that old Chrysler going strong with good compression, I'll feel a little better out on that Columbia.

Thanks again all

[Tim_Mattson]

Bolts.....

Brian,
Went out to the garage with new enthusiasm ....and promptly broke the last stuck bolt "nubben" that had been soaking on my buddies engine as described above.Weeks of patience ,all for not.
Got to drill the puppy out and realized it took a 3/32`` to start and maybe 6 bits to get to the final size.
The easy outs always break so tapping thru the old mess with heavy cutting oil restored order after about an hours time.
Main thing on the pilot holes is to use a clutched Drill set as low as you can go and AS SLOW as it can go,say 20 revs per minute.And pretty firm pressure,basically until you see material coming out of the tip.
"Read" the metal coming off the drill and try for long continuos strands.
"Listen" for the drill to creak and grab as it bites into the previous hole,back-up if it binds,clean the tip of shards every so often.
"Watch" for centering,angling slightly if you need to steer it away from an edge.Try to amke long continous strands of material.If chipping and breaking small fragments occurs,get a different size or tip style.
My tap was binding a little too much so I went ahead and used a bit 1/32`` bigger than the other holes.
The old bolt actually became a Helicoil on this one.
Major dosing of Gasket sealing compound and tapping out of all holes with seal this deal.
I took pics as I went and will post a "how-to" as Medic One did with the Shell Lake foaming.

Brian, I think you only asked for WHAT type of bits....

The $9.00 special pack of Dewalt bits was working well for me,needed some smaller sizes and they were cheap enough to try,the basic black carbide with a basic conical tip,nothing special just crisp tips.

Chyrslers are high on compession(140-175+),prone to blowing out spark plug inserts if not the Ring or pistons.They sure do perform when asked to.
A timing light and good or new Igniton stuff can get them firing off quicker and making real power.Carbs easily rebuilt right on the motor!
TM
ps if a stud is long enough for TWO vise grips (to form a Tee handle),it really makes it easy to turn once heated.Only head bolts and lower unit bolts would have enough left (if someone just ground off the heads,which some do first),then put the fluids right on the threads instead of hoping it reaches.

[Brian]

Sorry to hear about that nubby breaking off. I figure I'll be encountering at least a couple of those. But ya' know, busting off rusty bolts on an old outboard sure beats a 'good' day at work.

Got em' started soaking last night and they'll get more tonight. Tomorrow is the big day. All I could find right off for rust breaker was "PB". I haven't used this stuff before, but it was real thin and seemed to wick right into the threads. I'll be looking for the Tri-flow, Fluid Film and Aero-Kroil this week.

I get what you mean about getting long continuous shavings. With a drill press, good bits and soft material I've been able to do that before. Now I guess I'll be doing it with a hand drill and my back cramping up.

Heard a lot of negatives about Chrysler engines. Good to hear something positive. One motor (bad cylinder) came with the boat and the other I got with a 25 hp Mercury (bad reeds) for $120. The carbs from the other Chrysler (bad lower) are rebuilt and ready to go. Hopefully I'll do the block up right and have a strong motor.