I have a 01 NOrdic 28 heat with a 500 efi and xz drive. The motor and drive have just under 400hrs on them and have never been opened up.

I was running it yesterday i had it at WOT for approx 45 seconds running 5k rpm. Then I heard a loud "ping" noise like if you hit a steel plate with a bal pean hammer. It only did it once though. So I backed off to about 3500 rpm motor sounded great ran great all pressures normal. I got back into it and it made the same sound once more at 4500 rpm again with a slight drop in rpm.

I backed it down and put it in neutral she idled perfectly reved it a few times it was flawless. So I went back out to see if I could repeat it, and ran it pretty hard for 10 or 15 minutes and it ran perfect. I still have not been able to find an issue with the motor.

I pulled both magnets on the drive and they were spotless no metal at all.

So what gives?? Has anyone ran across this before. Please help!!

If they have 400hrs, the engines need to have the top ends freshened. You may have a broken valve spring. Also head gaskets are probably getting to let loose with 400hrs.

Wouldnt there atleast be a ruff idle if it was a valve spring? And how could I go back and run it for 20 minutes and it was running completely normal?

I was probably just a empty beer can rolling around.

LOL!

Checking your valve springs is a good annual project. The tool isn't expensive.
http://moroso.com/catalog/categorydi...?catcode=27105

Sounds like something hitting the inside of the bellhousing? My buddy had a 500EFI break flywheel bolts.

hmmmmm... now that would sound logical for the sound that i Heard. Is there an inspection plate or or any way to see if the bolts are indeed broken?

Pull the motor unfortunately. We knew something was bad wrong with his because the starter would not engage the flywheel. Flywheel was cocked out to where the starter gear couldn't grab on. Just the description you made of the sound made me think belhousing/flywheel/starter.

So I cranked the motor over without firing and didn't hear a thing. I tried turning it over by hand and still didn't hear anything rattling. How would the flywheel bolts come out with the coupler over it.

Any Ideas??