Pressure testing exhaust manifolds

how did you block off the rear discharge or elbow.?
i would take that apart and install flat rubber and seal it off.   then re pressurize it. Would think you should not hear any leaks, should not drop pressure. you can use soap water around all joints and schrader valve to test for leaks.   

You can pressurize the block the same way.   Plug everything up.   and put some air in it.

i did this before by taking intake off and making block off plates for the head water jackets and pumping it full of air. found crack pretty fast that way.   

shierh wrote: how did you block off the rear discharge or elbow.? i would take that apart and install flat rubber and seal it off.

Steve,
It sounds like you aren't familiar with Commander exhausts. Look at the picture Bruce posted. There isn't water porting between the manifold and elbow. You'll see the hose connection on the elbow. It's a great method to eliminate potential air pockets in the manifold.

Riley wrote: Water comes in and out of the front of the manifold,

Bruce,
They should hold all the air. Put them in a tub of water and look for bubbles. Make sure you aren't leaking air on your temporary air connection. If the engine froze, the manifolds typically go first. The pressure test is always recommended but the only downside is it's done cold. Cracks can open up when the manifold gets hot.

Port Manifold has aluminum oxide between the manifold and the discharge which is an indication of a leak.

Hope they are not cracked because then you have to change to these crummy cast iron center riser manifolds.   My First Nautique in 1978 had Commander in it and i preferred this type of manifold over the heavy cast iron type, at least for this type of application.   

My Hatteras had Crusader 454's that were heat exchange cooled and the only thing that got sea water was the Risers and Elbows along with the oil/trans cooler and Heat Exchanger. Weight wasnt an issue with that boat as the extra few hundred pounds would make no difference in its performance.   

block off all hoses on engine and put air in the block. i drain the block on both sides and then put the rubber tip air gun in it and put some lbs in the block.   Listen for hiss.   
u can use pcv pipe plugs and hose clamps . remember to block off raw water pump.   

Hope all turns out ok for you.   

Im in process of restoring 83.   Engine was new 12 years ago and put away 10 years ago, got ruined by leaving it full of water.   at some point the manifolds cracked from being frozen and water in a few cylinders, rusted but no frozen.   Boring it out 30 over, found heads cracked from being overheated as well.      also prior owner kept it covered from time to time using blue plastic tarp, turned it into a greenhouse inside and just played havoc on the thing.   

Gary, we cleared that area and made the driveway bigger so we could park more stuff. And we bought an engine hoist as I was afraid that eventually someone might get hurt. If you ever come visit me you'll be disappointed to see that set up gone. My kids are happy as they were a little self conscious about it when their friends from the city came to visit.