CMI header troubles with 500, 525, 575's ??
 

While looking for a used boat with 500's 525's or even 575's, (3 - 6 yrs old.) I been reading some disturbing threads about CMI headers cooking motors.
What is the best way to check or test for this trouble on a used boat? Which set up is least likely to fry?
Should I only concider 575's? Carbs, EFI's? This new bad news is very scary. Please help me to avoid a catastrophy and point me toward the right direction.

THx P

To date there is somewhat of a mystery as to just why these engine/header/silent choice combinations have failed. There are huge numbers of these products out there and most likely the majority have not failed. But because of business concerns no manufacturer has come out and said that their product did it and no one is really pointing fingers either because they depend on each other so much. So help from the manufacturers and dealers regarding this is OUT. The best thing is to keep following the threads and maybe when all the personal experience can be summarized we'll know what is really happening. Happy reading.

The CMI E-tops on the 500efi and 575sci's are pretty good and I have not read about any significant failure rate.

its been my experience that the 525's are most suceptible or prone to header failure. usually in the #7 cyclynder for what ever reason. there are signs of water on the spark plugs. i would suggest a compression test, a leak down test, and a pressure test on the header itself.
the light side is that you need a header the heavy side is a head due to a stuck guide or even worse a weak or destated cylyder.
it is also wise to ask if the headers Have been changed , if they changed the oil thermostat filter assembly. reason being that when a header goes bad it has been known to allow the saltwater into the oiling system and after the oil comes to temp the water evaporates . what remains is the salt crystals which either plug the oil filter giving you a false reading and or disrupts the operation of the oil t-stat giving high oil temps, low oil pressure and thus greatly diminishing the life of the engine itself.
sorry to be long winded and good luck in your search.

There's a couple ways to do it, here's what I've learned over the years of testing these headers.

1. Water Test: Attach a garden hose to the input of the header. Then rig a small valve onto the water dump at the top of the header. Turn on the garden hose with the dump valve open to expell all the air that's inside the header. Have a small flexible mirror and flashlight handy and an propane torch (heat wrench).... After all the air is expelled, close the valve so that it builds water pressure. Once you have full pressure fire up the torch and heat the welds around the primaries to see if you begin to see a leak. If you see water you have a problem. Use your mirror and flash light to shine inside the collector and angle the mirror so you can see where all 4 tubes come together inside the collector...check the whole area for leaks.

2. Air Test: fill the header with approx. 30 psi of air pressure. Have a bottle of spray nine, windex, soapy water etc...anything that will make bubbles.... Fill the header with air and spray the windex around the welds and inside the header. If you see bubbles you know you have a leak.

I prefer using water and heat, since that's the normal elements that the header is exposed to. Can't count the number of leaker headers I've found over the years....good news is 80% were repairable... The worst leaks are the ones in the collector, sometimes they can't be reparied.

what hesaid plus try to run the engines before you test them for a few minutes.