Pressure testing manifolds?

I know that there is a thread on testing manifolds, but I am having trouble finding it.   Would someone be so kind as to point me in the right direction? I picked up. A used set of manifolds for the 94 , and would like to bench test the before I install them.   

You have to block-off the riser.
meaning, block the water passage between the manifold and riser with like a rubber gasket etc....

I think it will take more than tape. Dr had a good idea, get some gasket material.

I would use 15 PSI. Do you have a kiddie pool? I would dunk the whole thing as long as you are going this far.

Thanks Guys, I'll try that tonight.   I do have a storage bin that can handle the whole manifold, and a radiator tester, so i'll give it a run.

Good point Kevin!   So part of the fun was testing,   part of the not so fun is that one of the manifolds was bad.... good thing I tested.   

I will take some pictures of the process, this is a question that comes up a lot

Art, That sounds like a good way as well! Mine were disassembled already, so here is what I did, there may be a better way, but this way seemed to work.

1.   Drill out a hole and install a "barb fitting" in a spare manifold drain plug ( if you have drain cocks, just use the drain fitting) I used put the barb fitting through the plug, and superglued it in place



2. Seal the water jacket openings between the manifold and the riser. I used aluminum tape and a sheet metal backer plate to keep the pressure from blowing the tape out.   Gasket material or rubber would have worked better, but I did not have any on hand.





3. re-assemble the riser and manifold, be careful not to damage the tape/gasket. tighten all four bolts on the riser so that the gasket seals good and tight



4. remove the brass elbow fitting at the front of the manifold, and install the barbed fitting/manifold plug.   Now, the water jacket should be sealed except for the opening in the barbed fitting.
   




5. I used a radiator tester (hand pump with gauge) to put air pressure in the manifold.   I connected the hose of the tester to the barbed fitting on the manifold



6. pump up the water jacket to 15psi as suggested by SNobsessed above

7. submerge the manifold in water and watch for bubbles. if there are bubbles, determine where they are coming from.   there should be no leaks from the manifold, however, if you made a poor seal under the riser, it will show up as a leak.




This one was a leaker... note the bubbles.   Here is a shot of the problem area.   the crack is about 4 inches long.




I hope that this helps someone else.   This was about a 15 minute job once I understood what I was trying to do...   thanks for the help from all those who posted above.

Great write up!

Art,
   I really appreciate your insight.   I have always been a car guy, so while the mechanical side of these boats doesn't intimidate me, I can certainly use the experience that others have to guide me.   I'll definitely check the assembled manifolds once I put the new riser gaskets on to be sure they are not leaking at the riser or at the gasket.   Since I am isolating whether the block is cracked or not, I want to make sure that I have eliminated all the problem areas.   I like permatex products, and will pick some up for the assembly process.