Dear Wareagle32789,

Hope you're well. The exhaust manifold is secured to the head by eight nuts, which go onto studs. If you found loose nuts, then the exhaust manifold gaskets need to be replaced. They usually come in a set of four. You might want to buy new nuts, as well.

One way to track an exhaust system leak is to wrap a towel around the suspect area. Have someone start the engine. Run the engine for a minute. If the sound is way less, then you've likely found the source of the leak. If the sound isn't much less, then remove the towel, allow the engine to cool, and try again elsewhere.

You might also inspect the pipes for signs of rust-through or cracks. Volvo down-pipes (from engine to catalytic converter) sometimes crack at the "Y" joint, between the engine and the catalytic converter. If there's a crack, it likely can be welded.

Before trying to remove the in-service exhaust manifold nuts, clean the ends of the studs with a wire brush. A Dremel (or similar hand-held tool) with a wire brush will help. Then, soak the nuts/studs with PB Blaster, Kroil, or a similar penetrating oil. Doing thes twice daily for a couple of days. Doing these things - cleaning and soaking with a penetrating oil - make it less likely that you'll shear a stud.

Before trying to loosen a nut, turn ever so slightly, as if you wanted to tighten the nut. "Slightly" means 1/10 of a degree, i.e., not very much at all. Do not put your full weight or apply your full strength to the wrench!! That amount of force isn't needed and could shear a stud. Slight movement can break any remaining corrosion bond. Then, gently try to turn the nuts. You may have "to work" the nut, to move it in both directions, to get it to turn freely. If you've cleaned the ends of the studs, that should greatly ease removal.

Once you've removed the nuts, loosen the brace that secures the exhaust system downpipe to the transmission. That will allow you to pull the exhaust manifold away from the engine by just enough, to be able to remove the failed gaskets, to clean the head and exhaust manifold surfaces with sandpaper (to remove rust, etc.) and to insert the new gaskets. Look at the gasket, so that the correct side faces the engine block.

I'd also clean the studs with a wire brush and apply a nickel-based anti-seize (or an anti-seize rated to 2,400°F or higher.

Hope this helps.

Yours faithfully,