Frozen bolts in cast iron head

[crash n bern]

Okay, this isn't on a bike, it's on a classic car.  But the wealth of knowledge here is immense so I thought it's my best shot.

The exhaust manifold gaskets are leaking on my Buick, and the bolts are pretty much rusted in.  There are some exposed threads on the top bolts that I have been soaking with Inox. Now I've managed to get one out and snap one.  The other problem is that some of the 9/16 bolt heads seem to be more like 17/32 so the ring spanner is a touch loose on them and there just starting to round a little.

I did take it to my mechanic, but he was too scared to snap the bolts and told me to soak them in Inox for a while.

Worse case scenario is to knock the heads off all the bolts, take the Cylinder head off and get a machine shop to drill all the snapped bolts off.  Then it would be stupid not to get the heads reconditioned and there's no point doing that without doing piston and rings and main bearings.  So to avoid a complete engine rebuild for the sake of a leaky exhaust gasket, does anyone have any secret recipes for rusty bolts in cast iron. keeping in mind that the motor is still in the car and I don't have the room to get a jackhammer in there.

[rocketfrog]

If you have access, give each fastener head a good clout with a hammer and drift to shock them a little before attempting to remove them. This might help the inox do its work as well. You could give them a working with the hammer and re apply the inox over night and re try the next day.

In my experience, a little heat is the trick. You could use an oxy torch or put it all back together as best you can and run the engine up to temp.

Get onto the bolts with a spanner or socket that fits snug while its hot (arm yourself with long sleeves and good gloves, maybe even have some cold water handy to quench a burn that you will most likely get).

When you do get the bolts out, replace them with studs (coated with neversieze) and use brass nuts.

Cheers Rocketfrog

[EML]

As an exhausty-we do this most days. If there is a bit left hanging out-weld a nut on it, the bigger the better, the heat transfer through the bolt will help loosen it, the work it back and forth-with your Inox spryed all over and it will most likely come out.
If not, drill a pilot hole down the middle and get more spray in there-leave it a while-good time for a cuppa , then try again. If still no good go up a size on the drill bit and work on it again, and so on.
Most mechanics want it to happen in an instant-after it's been there for 40yrs. 
Sometimes we can spend hours doing this and then we get in the shit for charging $400.00 for 6 studs
Not sure about the brass nuts-we don't use them-ever. And dont use spring washers as they will soften with the heat and then let go. ALWAYS retension after the first good run-we offer a free retension on all these jobs. That way it saves alot on warranty 12 mths later.

[crash n bern]

The problem with the bit hanging out is that it's the end of the bolt at the head and the room is tight, can't drill it unless I get a right angle drill attachment. It's a big block motor so room is limited. Have thought of welding a nut on.  I've got a fix it or die destroying it mentality so that will help.  Never thought of taking it to an exhaust shop, although for $400 might be more economical to take the head off.

[Slakewell]

I still bear the scares of broken bolt removal.
The definitive method I use is very tried ( over 15 years of doing this ) and find it 90% successful.
Worth roost off is the best penetrating oil , buy some it will make you happy.
Buy a high quality chrome molly welding rods I use WIA 312 in 2.5mm normally.
If you can use Stainless washers or black try and not use cad plated shit. Boat shops sell S/S washers.
Fit the washer snugly on the broken bolt then weld the washer to the bolt, now use a bit of flat bar steel or nut if you like and weld it to the washer. , I use a shiffter and slowly work it in both directions taping it with the palm of my hand rather than just turning it. and take my time, apply more Roost off after welding.   

[crash n bern]

Would Mig welding it work or is arc better?

[Davey Crocket]

I'll take all your pain away Bernie, ring this number, he'll come to your house and do it, thats all they do.....0418885463

[EML]

That's why I asked where he was DC. What would you know anyway-you're a bloody spanner jockey..
I just ahd my apprentice do his last papers for qualifying and I asked him what it was all about. He said they just had to take all the exhaust knowledge out of his system so that he could pass. Took over two hours and now hes got his papers he wont touch a muffler!! FFS I'll have to savk him and find a newby 

[crash n bern]

I'll take all your pain away Bernie, ring this number, he'll come to your house and do it, thats all they do.....0418885463

Yeah, but I'm the kind of bloke that will spend 3 hours on the side of the road fixing the car with a Leatherman, when I'm ten minutes down the road from home, while the missus stands in the background saying "Just call the towtruck". 
I'll have another bash at it and see if I can screw things up enough so that bloke can really earn his money.  Then I'll call him.

[EML]

Yeah, good idea. Break an ezy-out or two off in there, one or two l/h drill bits as well. Make sure it's in a position where no-one can see in there and add some after-market stuff so it's really hidden.
Then call him and say "that's how it was when it got there"-he'll love you for ever.

[Davey Crocket]

Bloody jumped up exhaust fitters, what would they know?....cause more problems than you could poke a stick at.......one foot out of a wrecking yard

[matcho mick]

ROST OFF,or for getting fugging very serious upspec to Rost Off ICE,
ps juries still out on Chemtechs Yield

[EML]

could try some "start ya bastard"

[crash n bern]

I couldn't find any rost off, but I got some loctite freeze stuff and a set of Irwin sockets for rounded bolts. Trouble is I can't get to the bottom bolts to spray anything on. The top ones have exposed threads where they come through the heads. I could cut the exhaust off, pull the motor out and just drop a 500 cube crate motor in and be done with it.  The bolt I snapped, I was working back and forth, I thought it was coming but it gently sheared.  I might start the motor and warm it up and try the freeze stuff on it, otherwise I might surrender and pay Davy's bloke to have my headache.

EML, what are the best brand of easy outs to snap?  Should I use el cheapo's or am I better off snapping some good quality ones that would be harder to get out.  I don't know why they call them easy outs, they should call them snap ins.

I recently had an aluminum axle adjuster frozen in a steel DG swingarm.  I made some penetrene out of acetone and auto trans fluid that I read was the best penetrating formula.  I soaked it for weeks to no avail and ended up cutting a slice in the swing arm and welding it up again.

Thanks to everyone for the advice.

[firko]

I could cut the exhaust off, pull the motor out and just drop a 500 cube crate motor in

If you do Bernie, can I buy your Nail Head engine ?