Pressure testing ?
 

:(Can you pressure test the CMI's while they are still on the block ,assuming an air test is done ? Can you plug the outlet that goes to the tailpipes and pressurize from the water intake side?????? anyone tried this or done it sucessfully? any advice

i don't think it is possible because the last time i saw a cmi header it had mulitple holes for the water to exit. what is your issue? water in the cylinders? or leaking externally? i think you can send them back to cmi and have them tested.

On mine, they can be tested while on the block. The multiple water outlets are in the separate tail pipe, not the header. The header has a jump over hose at the header flange to tail pipe. The hose is where all the water exits and is where the pressure test is done. But you must plug all the other water inlets to the header.

If you look on attached, mine only requires two areas to be plugged. The water inlet at the bottom of the header and the water outlet at the flange jump over. You'll even see that 1 header still has the rubber cap on the jump over outlet that was recently tested.

Very Simple To Do. Use A Leak Down Tester Tool. 20 Psi Is All The Air Pressure You Will Need.

Thanks Guys ,Thats what I was hoping ,I'm purchasing a used boat with the 500 efi's and the CMI exhaust ,all the horror stories have me worried,so I am hoping to ,get set up to do a periodic pressure test of the headers,seems like thats the only line of defense to avoid buying all new heads or even worse! And pulling the exhaust every time you want to check is not practical ,but if its just disconnect a few hoses ,plug and test ,then it sounds like a good policy to avoid failure related problems . Any thoughts ? Anybody already do this??