Exhaust manifold leak?

[wegngis]

I think I've got an exhaust manifold leak on the rear passenger side. When the engine is cold I swear I can see exhaust coming out back there. Once it heats up it stops, meaning metal has expanded and sealed it up (I think). Last night I started hearing a very faint tapping back there, too.

The main question is, can I just re-torque the bolts? I've seen mention of torquing while hot, but it seems like torquing while cold is the right thing to do. I know the gasket might be toast, but I figure a re-torque is a good first step, right?

 

[broncobilly72]

Some times the bolts back out by themselves. I had the same problem with my 68 ford truck. The solution: took headers off, installed thicker Mr Gasket gaskets, then added a set of locking header bolts. It worked for me!

 

[Heus33]

I have always re-torqued while hot, just be careful not to burn your hands.

Long socket extensions and a good pair of gloves will be your friend here.

 

[Explorer]

"Torque" is the key word here. Last thing you want to do is break one off.

 

[wegngis]

"Torque" is the key word here. Last thing you want to do is break one off.

Believe me, I hear ya.

Doesn't it seem if you torque it while hot, the cooling will cause the metal to contract, thus loosening the bolt? I'm no expert, just throwing out ideas...

 

[Steve83]

No, the bolt, manifold, & head are made of steel (cast iron is chemically similar), so their rates of thermal expansion are virtually identical. So as one contracts, they all do, and the bolt's clamping force will remain nearly constant over the full operating temperature range.

It's when you mix materials that you have to worry about temperature/size changes, which is why Aluminum heads on cast iron blocks are so easy to warp.

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