bowtiebrad

My big block has a bad exhaust leak, I have new copper gasket for it and am ready to go. I tried today to see about breaking the manifold bolts loose but no luck, I have sprayed with that new wd-40 rust specialist stuff on and off a couple times but didnt help really. I havent put the hurt on them because i dont want to break a bolt nor do I have the tools to fix that problem. I only have a regular set of sockets n wrenches and what not, no torches or impacts to assist me. Does anyone have some tips to help me get these loose so I can gasket them? the shops want to much to do it for me. Thanks

MDchanic

Actually, without a torch, or the ability to drill out a broken bolt, I'd say the answer is No.

To the extent that most of the holes are open at the backs (the center hole on some is blind, on others is open), a good penetrant (I like KROIL, a comparison in a machine shop magazine [I forget which one] showed 50:50 acetone and ATF to be the most effective) sprayed so that it can wick in through the backs of the holes is your best bet.

= Eric

bkeese

First question, are you sure that the leak is between the head and the exhaust manifold. That's kind of unusual. I would suspect the manifold and header pipe to leak.

Penetrating oil will never get to the threads, nor will heating help. I think your best chance is to use an impact wrench. The fast hammering should break the bolts loose before they break.

Kennybill

Always use a 6 point socket, it will give you the best shot.

droldsmorland

With Kroil, PB Blaster or Castles Thrust and some relatively hard tapping on the heads of the bolts and a lot of patience they can come out nicely. Also thermal cycling with the engine and penetrant can help. So a cycle of heat then penetrant, repeat several times. Don't let engine warm up hot enough to vaporize the penetrant. Do this for a couple of days all the while tapping the heads of the bolts when hot and ambient.
If that doesn't work find a service garage with someone who knows how to gently operate a 3/8 drive air hammer. You don't want to horse them out rather go gently and let the hammer blows from the impact do the work. A good mechanic will know how to finess them out with an impact and penetrant.
The next step is to break them and hope there's enough of a stud left that you can get on them with a torch and vice grips with a water quench. Hopefully you dont need the last step...drill tap or better yet EDM. EDM requires head removal. It stands for Electric Discharge Machining and removes the fastener while leaving the threads intact. It basically burns the bolt out with a intense finely concentrated current discharge, I call it simply magic! But hopefully the first method will work for you. The later solutions are reserved for an engine that's been abused or sitting exposed in a field or under water. Usually the threaded portion of the exhaust manifold fasteners is in relatively decent shape its the head that deteriorates. So snapping the heads off isn't catastrophic as whats left will usually come out with very little coaxing. Just make sure that this is the leak source and its not the head pipe flange which is generally the case.

joe_padavano

You did bend up the lock tabs around the bolt heads (if they are still there), didn't your?

oldcutlass

And now we know why!

You have stumbled on one of the worst nightmares of auto repairs, the exhaust system. All good sugestions above, the only thing I can add is patience, because it can go from just ugly to a royal pain in the a$$ with 1 slip of the wrench.

Know your limitations, and there does come a point that if you do not have the proper tools to perhaps pay someone who does.

72 w29 all green

X2 on every word you said. fortunately, I've yet to snap an exhaust manifold bolt, but i've always used a combination of a torch, Aero-Kroil, a hammer and patience. For me it's pay now or REALLY pay later, not only regarding cost but the added time and aggravation once you snap a bolt.

bowtiebrad

All good points guys thanks. I think that it may be best for me to suck it up and get someone to do this for me since i am not equipped to deal with this properly. Big help!!!!

droldsmorland

One additional note. To prevent this problem from reoccurring in the future lather up the new fasteners with high temp anti-seize (copper based), Said fasteners & washers or French locks should be of the same grade & size as the ones removed (read NOT chinesium junk you'll be sorry if not).
Most of the aftermarket parts & exhaust houses should have USA fasteners....just ask.
Back off on the torque spec 10% when using anti-seize on the threads unless the spec is a wet torque spec...but I believe its a dry spec. Recheck this torque after about 5-10 thermal cycles to compensate for any gasket compression if used..