Donzi38ZXXX

I have been reading the posts on leaking headers on various engines - and I am concerned. I have 2000 500EFI's with 192 original hours in my 2000 38zx. They have never been apart - still have all the bolts wires on. The boat has been in freshwater except for brackish water this past season - but flushed. They are well maintained by myself and not considered run hard. When should I take the headers off to be checked for leaks. You guys are great - thanks for your help.

James

While this is a potential problem, you are probably at low risk - if you have not had a problem then any leak you may have a small leak - You have realativley low Hp and run it at lower Hp setting - so the heat/cold s tug of war is not as much as if you are pumping 800 + hp through the same pipes -When you tear down @ 250 hrs to replace roller lifters ----- then pressure check your headers

Too Old

Personally, I'd have seven year old headers pressure checked.

Donzi38ZXXX

TOO OLD - JAMES,

Thanks for your reply. If I wait til after this coming season, I should have close to 250 hours on them. Which at that time I am planning on doing the top end of the engines. What am I risking by waiting another season. - Also, - what signs would I look for that would indicate leakage without taking the CMI's off. Thanks. Ted.

MarkDonzi

I've had two sets of CMI's leak on my boat. First (120 hours) one water got into oil, then plugged the oil filter. Oil then goes thru by pass instead of oil cooler. So your first indication will be sky high oil temps. Second (170 hours) one drained water from header into an open exhaust valve partially filling a cylinder and toasted the motor when it was started. If I were you I would have them checked now. It's not a big deal to R & R the headers and a lot cheaper than a rebuild.

Donzi38ZXXX

Thanks Mark - I will R & R the headers when I unwrap the boat around March. Can I pressure test them or do I have to send them somewhere. I really appreciate your advice. Thanks Ted.

MarkDonzi

Me mechanic did all my work. 525's have aluminum heads and I don't want to mess them up. I'm not sure what the 500 EFI's have. I'm trying to figure out a way to pressure test mine without removing them. Anybody done this before?

Donzi502

Put a preasure gague in a fitting and blow it up with a compressor through another fitting. You will soon know if they are leaking. You will probally hear it. Personally i think the best thing to do is treat them as if they are leaking. Put taps on the end of the water feed log and drain them every time you shut down. Some long extensions make this easy. A very small bilge pump with small line and non return valve will empty the bilge. Fire the engine when empty. Another way is to run very small lines from the end of the log to a small pump and suck them empty when you shut down. Just figure a way to keep them empty an you will have no trouble. Jas

Ted G

iTrader: (1)

You can use caps on the water inlet and outlets and then make use a hand pump-preferably or a compressor-set the pressure low and see if you hear a leak. I also saw a guy with a radiator neck from a foreign car adapted to a hose, clamp the hose to the header, pump with a radiator pressure checker and watch the gauge for a drop-pretty good PM since CMI's are VERY leak prone after a couple of hundred hours.

Big Block Billy

Be careful , check them plug them up and pressure test them.
I did this with a garbage pail ful of water and apx 25 psi of air.
CMI allows for 1 weld repair and then they are scraped if they fail the test.
Stainless is 80% iron. The headers cycle between hot and cold and are brittle to begin with.
Newer CMI headers have cool collars and are just made better than the older ones, because even they learned something over the past few years.
A friend of mine was scammed into buying used headers, and they messed up his motors too.
You could put a petcock in the back end of each header and drain after use to keep water from draining into motors.
All headers must be flushed with fresh water after use even if not running in salt water. BBB