Exhaust manifold gasket leak significance

[kaliona]

I'm bummed I just reinstalled my 165hp L6 engine in the boat. No oil leaks, no water leaks, starts right up and idles smooth. All good except for an exhaust leak I can hear. I put my hand up under the exhaust manifold next to the block and can definitely feel air blowing down from between the head and the exhaust manifold in one area. I was meticulous about cleaning both surfaces before assembly, installed new gasket, and torqued exhaust manifold to specs. I re-torqued after running on the ear muffs for about 30 minutes. If it is in fact a leak at the gasket, would it be a bad idea to keep using the boat that way? What bad things could happen if not fixed right away?

 

[tank1949]

I'm bummed I just reinstalled my 165hp L6 engine in the boat. No oil leaks, no water leaks, starts right up and idles smooth. All good except for an exhaust leak I can hear. I put my hand up under the exhaust manifold next to the block and can definitely feel air blowing down from between the head and the exhaust manifold in one area. I was meticulous about cleaning both surfaces before assembly, installed new gasket, and torqued exhaust manifold to specs. I re-torqued after running on the ear muffs for about 30 minutes. If it is in fact a leak at the gasket, would it be a bad idea to keep using the boat that way? What bad things could happen if not fixed right away?

I have had friends who double gasket Chevy V8s.

 

[Scott Danforth]

If you leave it.... Best case, you fill your bilge with exhaust fumes

Worst case, if your running rich, you could fill the bilge with fuel fumes and you have an open ignition source

I would fix it

 

[kaliona]

If you leave it.... Best case, you fill your bilge with exhaust fumes

Worst case, if your running rich, you could fill the bilge with fuel fumes and you have an open ignition source

I would fix it

After further investigation I discovered that the tube running through the exhaust manifold that heats the choke was not fully seated so the exhaust was blowing out the bottom hole. I pushed the tube down to cover that hole and all is well. What a relief.