OK, I know this has been talked about alot. I am convinced that I should pull my original 500EFI headers (193 Hrs) and test them for leaks. The boat has been in freshwater its entire life except for last season at my house in brackish but flushed. I pulled the spark plugs and did a compression test and there is no indication of problems from inspecting the plugs or the compression test - BTW I will be performing leakdown test also. Anyhow, It seems to me that the best way to test these headers is to remove them from the boat and plug them except where I will apply air pressure - set it up with a maximum of 25 PSI air pressure then submerge them in a tub full of water and look for bubbles. Does this seem like the best way. I would be doing this this weekend but it is raining like hell. Thanks Ted.

The way I do it is to hook a garden hose to the distribution hose at the bottom of the header. Slowly turn on the hose and fill the header with it standing up. When it is full, turn off the hose and put a cap on the outlet fitting that goes to the tails. Turn the hose back on and let it sit for about 5 minutes. If water is in the pipes, it leaks. The garden hose's male end should fit right into the 1" hose on the headers and clamp tight. You can put a hose on the outlet fitting and put a plug in it, or go to the hardware store or auto parts store and find a 1" rubber cap for the outlet. Hope this helps, Eddie.

i pulled my CMI's over winter and used a automotive radiator pressure tester that has a gauge on it, capped off all connections and pressured them up, needle did not drop on the gauge, i was lucky, I did have to cut the rad. cap end off the pressure tester and come up with some adapter fittings but it was easy,

Has Anybody tried to plug the hose outlets and air test the headers without removing them?

that wouldn't be hard mark , but I like the garden hose method as described by young although I like to see 35-40 psi just rig as he said and turn hose on if headers are off will see right away

Mark,
That is a good idea. As an initial test (or hopefully a final test) why can't I take my Leakdown Tester tool (Gauges) and block off the the other water exits. If it doesn't leakdown - why take the header off? What do you all think?
Ted.

why not , of course that will work

Spoke with CMI today - They said when using air pressure with a leakdown gauge set to only use 20 PSI.

I have 2002 model 500 EFI with stock CMI's. Just turned 380 hours and no problems at all. Have two friends that both have 500 + hours and still running the stock headers.

Guess we are lucky, I plan to check them out good next winter.

Thanks for the thread and the suggestions on how to test them.