Broke cyl cover bolt

[RadarRick]

Early 90's 15hp Merc

4 out of 6 bolts holding the cylinder cover are badly rusted. I tried removing one but it broke off.

Before I try the others, what's the best way to remove them to avoid breaking? I've got PB Blaster and have soaked them a few times. Any other suggestions?

Once I get the other bolts out (hopefully without breaking them) and remove the cover, I'll remove the broken bolt(s).

Thanks

 

[robert graham]

Re: Broke cyl cover bolt

Take a little propane torch and put some heat on each one, let it cool, heat it again, that can help loosen them so they don't break. Soaking them overnight with that PB Blaster can help some too. Good Luck!

 

[RadarRick]

Re: Broke cyl cover bolt

Thanks - I'll try that & will post result

 

[spamn]

Re: Broke cyl cover bolt

I just had the exact same problem on my Merc 402. Are the backs of the bolts visible on that engine or are they buried inside the block wall?

 

[redjmp]

Re: Broke cyl cover bolt

Don't think the propane torch is going to do it... You need an oxy/acetylene torch.

You want to heat up just the head of the bolt until it just gets red hot and then try squirting some pb blaster on them and letting them sit overnite.

Heat them up again and then try using a small impact driver on them.

You need to be very careful though not to heat up the surrounding aluminum because it will not change color at all before it just melts like solder.

Usually if they snap, its right at the head leaving a stub you can usually get a pair of vice grips on afterward and they usually come fairly easily then.

 

[RadarRick]

Re: Broke cyl cover bolt

Spam - These ones are open-ended - not buried.

Red - I was thinking about a MAPP torch. It's hotter than propane, but will it be hot enough?

Yes, there is enough room to grab them with vice grips. I've been drowning them with PB Blaster and working with the grips, but they aren't budging yet. I don't want to really yard on them for fear that they'll break off again.

All 3 broke off quite near the head. I'm guessing that is due to electrolysis weakening the steel. The heads had a fair amount of rust and the 3 bolts that did come out had white, powdery build-up full length.

 

[MercNub]

Re: Broke cyl cover bolt

I had a bolt snap on my 50 hp cylinder cover also. What ever you do do not use one of those bolt remover tools. On mine the tip of the bolt remover snapped off inside the broken bolt and was impossible to drill out since it was made of harden metal. I finally got the broken piece of bolt remover tool out. I fixed mine by drilling the old screw out and re-tapping it back to fit the bolt.

If the end of the bolt protrudes towards the front of the motor, mine stuck out about 1/4 inch or so. Coat the threads with Vaseline and let sit for a couple of days. Slowly without full force, try to turn the bolts to loosen, I originally used a 2 foot breaker bar which snapped the bolt after I got it out about halfway. Also if they do start to loosen squirt pb blaster under the bolt head and tighten and then loosen the bolt slowly to work the pb blaster in. Forcing it will only freeze the bolt into the power head. By using this method I was able to save the other bolts from snapping off. Also if the bolt holes in the power head are rusty you may have to run a tap down each one to clean them out. Vaseline also helped remove the rust here too.

Good luck.

 

[redjmp]

Re: Broke cyl cover bolt

Well I'm not sure about the map torch. Is it hot enough to weld with? The steel needs to get just slightly red hot as this will exceed the melting point of the aluminum that its binding to and allow the bolt to come out easily. The use of a small impact driver will break them free without the heads breaking off. You now want to make a mask that just exposes just the stud and covers the aluminum before applying heat. Get the vice grips on the red stubs and slowly work them back and forth and they will come out.

 

[coolguy147]

Re: Broke cyl cover bolt

propane. act/oxy is too hot for alumium.

if you must then drill a tiny hole to the threads so the fluid can penetrate.(last resort) but do this while it's warm so it will draw in the fluid.

weld a nut on it so you can twist it out? heat also.

 

[redjmp]

Re: Broke cyl cover bolt

propane. act/oxy is too hot for alumium.

Thats the whole idea. You need to heat to joint between the two metals enough so that the aluminum just starts to give releasing the bolt. But you don't want to heat the aluminum with the flame, just the heat transferred from the steel, therefore the mask.

In my experience, propane just won't cut it. You can try till your face is as blue as the flame as I have but you won't get anywhere. Its just not enough heat.

You only want to get the aluminum threads hot and not the block as aluminum has a nasty habit of warping when it gets too hot.

 

[coolguy147]

Re: Broke cyl cover bolt

Thats the whole idea. You need to heat to joint between the two metals enough so that the aluminum just starts to give releasing the bolt. But you don't want to heat the aluminum with the flame, just the heat transferred from the steel, therefore the mask.

In my experience, propane just won't cut it. You can try till your face is as blue as the flame as I have but you won't get anywhere. Its just not enough heat.

You only want to get the aluminum threads hot and not the block as aluminum has a nasty habit of warping when it gets too hot.

propane is the safest since it wayy below alumium's melting point but act/oxy will get up to that critical heat range

if anything send it to a machine shop to get taken out. saves you the swear jar and stress

 

[redjmp]

Re: Broke cyl cover bolt

propane is the safest since it wayy below alumium's melting point

Yes safest and ineffective... Have you ever removed any with a propane torch?
Never worked for me....

 

[Moody Blue]

Re: Broke cyl cover bolt

Another trick to try is to sharply rap (use common sense ) the head of the bolt a few times with a hammer before trying to unscrew it. The jolt sometimes helps to break the connection/corrosion between the two metals.

I have had good success using MAPP gas on the smaller fasteners, say up to 3/8". You need to get the bolt hot fast without heating much of the surrounding material. An oxy torch in the hands of an inexperienced user is asking for trouble and it is not as readily available to the typical DIY'er.

 

[coolguy147]

Re: Broke cyl cover bolt

Yes safest and ineffective... Have you ever removed any with a propane torch?
Never worked for me....

like i said smart A

send it to a professional....my machine guy used a Acy/oxy to heat it up.

he then welded a nipple on it if it was broken flush but if not he welded a bolt on it then twisted it off.

please be a jerk to a teenager who's just starting to learn about these things....on some other website with more people like you =)

 

[coolguy147]

Re: Broke cyl cover bolt

:eoh yeah, the bolts that he was working on were soo corroded that he had to drill a tiny hole into the threads and put penetrating fluid in it.

then heated it to draw the fluid in

any torches will take paint off sooo be careful. keep away from oil residues but a flare up might happen

what about the candle wax method?

 

[redjmp]

Re: Broke cyl cover bolt

like i said smart A

send it to a professional....my machine guy used a Acy/oxy to heat it up.

he then welded a nipple on it if it was broken flush but if not he welded a bolt on it then twisted it off.

please be a jerk to a teenager who's just starting to learn about these things....on some other website with more people like you =)

What? You're telling me you are a 16 year old kid?

hahahahaha!!!!!!!!

Son I've been turning wrenches since way before your papa was even a gleam in you're grandpa's eye.

Are you saying I should shut up and listen you?

You are an embarrassment kid.

Wasn't trying to be a jerk, just asking a straight up question? But now I will be, just to return the honour!

Have YOU ever removed a broken bolt with a propane torch? No didn't think so....

You'll end up breaking the stub off in the block.

Been there at one point and done that.

Now you are really insulting me when you say the OP should take the thing to a professional to do exactly what I said to do and that is use an oxy/acetylene torch.

Just because this is beyond your abilities because you don't know how to use an oxy torch doesn't mean a grown man with some skill can't manage to do this job.

You are a pompous idiot for posted about something that you have no experience in.

I guess you must think that because you have a few thousand posts more than me, that you are smarter and more qualified to give advice?

Bozo.

 

[coolguy147]

Re: Broke cyl cover bolt

What? You're telling me you are a 16 year old kid?

hahahahaha!!!!!!!!

Son I've been turning wrenches since way before your papa was even a gleam in you're grandpa's eye.

Are you saying I should shut up and listen you?

You are an embarrassment kid.

Wasn't trying to be a jerk, just asking a straight up question? But now I will be, just to return the honour!

Have YOU ever removed a broken bolt with a propane torch? No didn't think so....

You'll end up breaking the stub off in the block.

Been there at one point and done that.

Now you are really insulting me when you say the OP should take the thing to a professional to do exactly what I said to do and that is use an oxy/acetylene torch.

Just because this is beyond your abilities because you don't know how to use an oxy torch doesn't mean a grown man with some skill can't manage to do this job.

You are a pompous idiot for posted about something that you have no experience in.

I guess you must think that because you have a few thousand posts more than me, that you are smarter and more qualified to give advice?

Bozo.

ok. Have fun.