71 Johnson 9.5 - broken screw in cylinder head

[joho5]

grr...well I had recently put a brand new cylinder head on due to a stripped spark plug hole. After my trip today, I was going to re-torque the bolts that hold the head because the manual says to after the engine has been run and cooled back down to touch.

First one I torqued, it broke..damn! Anyways, I had my wrench torqued to 120 inch pounds per the manual, still broke. I think they are just old obviously.

There is good chunk of the screw sticking out of the threads still (i removed the head).

Here is my question, I have never backed a broken screw out. I do have the tools to do it, but without having experience, I am a little weary doing it.

Should I try this, or just take it somewhere who has experience?

also, is this a special bolt, or can I just go get the same one at a local store? and I assume its stainless?

thanks

 

[lyncraft_mechanic]

Re: 71 Johnson 9.5 - broken screw in cylinder head

well if i were you i would try and back the broken bolt out with a pair of visegrip pliers. are you sure you set your tourque wrench to inch pounds and not foot pounds? you can get replacement bolt at this website http://www.shop.evinrude.com

 

[joho5]

Re: 71 Johnson 9.5 - broken screw in cylinder head

its not enough sticking out for the vice grips to grab it. I have a left hand bit, and a screw extractor bit. I just didnt want to mess it up to where it cant be repaired.

 

[lyncraft_mechanic]

Re: 71 Johnson 9.5 - broken screw in cylinder head

in that case your other option is to drill a hole in the center of the bolt and use a easy out!!! try using a center punch and pre drill the hole with a small drill bit

 

[Benny1963]

Re: 71 Johnson 9.5 - broken screw in cylinder head

dont use and easy out there horrible drill it out with left handed bit if that dont do it have it drilled and helicoiled about 30 dollars around here

 

[Boatdood]

Re: 71 Johnson 9.5 - broken screw in cylinder head

I see you have conflicting advice here on the easy out route to remove that bolt. I agree with both, if that's possible. Generally when it comes to outboards in salt water use the bolts that wring off do so because the threads are frozen from corrosion. The easy out is worse than useless in those cases. What can and usually does happen is that the easy out wrings off and now you have a much harder material in the bolt that is way harder to drill out. When corrosion is present I go straight to the drill out the whole thing and helicoil it route. In the case mentioned here though the bolt was very recently installed and should be free in the threads. Therefore it should spin out easily if only a grip could be obtained to do so. An easy out may work just fine in this case. The left hand drill bit is a good idea as well. The idea is that the grip of the drill bit may be enough by itself to spin the bolt out of the hole. If not, I might be a bit hesitant to try the easy out unless it is of the type I can easily take out if it doesn't do the job, then proceed to drill the whole bolt out. Good luck with it.

 

[joho5]

Re: 71 Johnson 9.5 - broken screw in cylinder head

if in the process any metal shavings or anything like that gets in the cylinders, is that ok? Will it just send it out the exhaust?

thanks

 

[joho5]

Re: 71 Johnson 9.5 - broken screw in cylinder head

I know that bolt can be obtained from evinrude, but does anyone know the size and length. I would rather go and get it from a local hardware store if I could so it isnt so expensive.

and are the screws that go into the head, stainless?

thanks

 

[asdasc]

Re: 71 Johnson 9.5 - broken screw in cylinder head

Heck, with it loose in the threads, I would try to work it out with a pick until you can grab it with something. Another idea is to use a dremel with cutting wheel to make a small slot for a screwdriver to fit in.

On head bolts, I am a little afraid to start using any old bolt that fits. They are holding down a LOT of pressure. There is too much safety risk for me and my family. It is worth the couple extra bucks and wait for the right parts.

By the way, good call on the ft/lbs vs in/lbs. I am thinking that 120 in/lbs wouldn't break most (any?) bolts.

Good luck with it, and try your best to keep any shavings out of the motor. That can't be a good thing!

 

[Boatdood]

Re: 71 Johnson 9.5 - broken screw in cylinder head

Joho, the shavings in the cylinder can be minimized if you stuff a wrag in the cylinder before you start, but they are easy enough to wash out with a solvent and compressed air. I also like to flush some gasoline through the intake and crankcase after a repair is made by choking the engine and pulling it over until the engine floods and I see gasoline flowing into the cylinder. That's fairly easy on a downdraft carb like the 9.5 has on it. Do this before you put the cylinder head back on. The head bolts are a better grade on those engines but you can get better bolts at a hardware store that will work. The trick is to get bolts that are exactly the right length for thread engagement without overdoing it. Stainless comes in various grades of hardness as well. Evinrude and Johnson does use a lot of hard stainless in their engines, much harder than the Japanese counterparts. I know all the warnings about using dissimlar materials in conjunction with salt water but sometimes a stainless bolt works better.

 

[Tim Frank]

Re: 71 Johnson 9.5 - broken screw in cylinder head

It is worth the couple extra bucks and wait for the right parts.

By the way, good call on the ft/lbs vs in/lbs. I am thinking that 120 in/lbs wouldn't break most (any?) bolts.

Good luck with it, and try your best to keep any shavings out of the motor. That can't be a good thing!

Do not get shavings into the cylinders. Fastest way to score the $%^#@ out of the cylinder walls that I know.

Definitely worth getting the right grade of bolt, but if you take a sample to a good fastener shop they will be able to match you up OK.

120 in-lbs is fine for a head bolt and is actually 10 ft-lbs. I am o/hauling my snow blower and its head bolts are spec'd at 200 in-lbs!

If you are not really comfortable doing this, if you have a drill press or access to one, make a dummy head from 2x lumber, drill every third hole (starting next to the broken bolt and stopping before you get back to it) using the head as a template and a drill bit that is on size with the holes in the head. Drill the hole that matches up to the broken bolt with the drill that you will use to drill out that stub. Make absolutely sure that that drill is smaller than the tap drill size for the head bolts. I would say at least 50 thou smaller.
If I had to guess, the bolts are probably 5/16- 18NC (but check). If so, and only if so, that would make the tap drill letter F and so I wouldn't use anything bigger than 7/32" Left hand drill on the stub. If you have a 3/16" LH that would be safer still.
If these are not 5/16" all the above is not applicable and you'll have to extrapolate from the correct size as I did with the guess at 5/16".
Get some bolts that are long enough to bolt this dummy head in place and seal the gasket surfaces with a layer of grease when yopu bolt it in place.You only need to snug the bolts up maybe a half turn past finger-tight.

You now have protection against debris getting into the cylinders, and what amounts to a 1-1/2" long drill bushing/drilling jig. This should allow you to drill straight and true.


Of course if you are more adventurous, you can do the same just with the cylinder head, but since it is much thinner you don't get nearly the effective guidance for the drill bit; it requires a steadier hand and better eye.

Good luck.

 

[wlbolerdo]

Re: 71 Johnson 9.5 - broken screw in cylinder head

Today I broke 3 bolts in my exhaust housing adapter on my 70 horse! It's about $221.00 and the megaphone it's attached to is $121.00! I let a machine shop remove them for $55.00(their minimum charge). They were broke off below the surface and they got them out without having to re-tap. No headache for me!
Wayne

 

[ezeke]

Re: 71 Johnson 9.5 - broken screw in cylinder head

96-120 inch pounds is the actual factory spec, so 120 is the upper limit if you really trust your torque wrench.

The trick is to be sure the holes are clean so that the screws don't bottom on 30+ years of debris.

 

[fixmyevinrude]

Re: 71 Johnson 9.5 - broken screw in cylinder head

Maybe this will help. Put your old head back on. Take a drill bit the same size as the clearence hole in the head and use the the hole as a guide for the drill bit. This will do two important things. First, it will get you centered on the old screw which is important when trying to remove broken screws. Second, it will keep the chips and shavings out of the cylinders which is also very important. When you start drilling you just want to start the drill in the bolt, you are only trying to make a good center mark in it and you don't want to hit the deck of the powerhead. Now take a smaller left hand drill and carefully find the center mark you made and begin drilling keepig your drill straight with the old bolt. You may want to have someone watch you from a few feet away to help you keep the drill straight. Many times the the old screw will walk right out. If it does not I would try a EZ Out. If you had the screw out and only put it in to 120 in/lbs and it broke it should not be in that tight. You can use a left hand drill for the first step if you have one but if you don't a standard right hand drill should be fine for this step.

If you do not have the old head any longer you could use the new head wth a transfer punch, center punch, center drill and left hand drill. If you need help or don't follow what I have described here let me know and I will help you.

 

[fixmyevinrude]

Re: 71 Johnson 9.5 - broken screw in cylinder head

Maybe this will help. Put your old head back on. Take a drill bit the same size as the clearence hole in the head and use the the hole as a guide for the drill bit. This will do two important things. First, it will get you centered on the old screw which is important when trying to remove broken screws. Second, it will keep the chips and shavings out of the cylinders which is also very important. When you start drilling you just want to start the drill in the bolt, you are only trying to make a good center mark in it and you don't want to hit the deck of the powerhead. Now take a smaller left hand drill and carefully find the center mark you made and begin drilling keepig your drill straight with the old bolt. You may want to have someone watch you from a few feet away to help you keep the drill straight. Many times the the old screw will walk right out. If it does not I would try a EZ Out. If you had the screw out and only put it in to 120 in/lbs and it broke it should not be in that tight. You can use a left hand drill for the first step if you have one but if you don't a standard right hand drill should be fine for this step.

If you do not have the old head any longer you could use the new head wth a transfer punch, center punch, center drill and left hand drill. If you need help or don't follow what I have described here let me know and I will help you.