Well I have been running a HP 500 EFI for the last 12 yrs and actually have approx 535hrs on the motor and everything was running great until last week.....While running up the river from Havasu decided to kick it up a notch and trimmed the boat out and was running the motor at 5100rpm when i saw the tach drop by 300rpm.....I shut it down and there was never an alarm for anything...fired it back up and the boat was running at 180 deg. and everything seemed OK...went for another run and same thing...Trimmed up and running solid at 5100 and then came the 300rpm drop so i knew something was up and so i lowered it down to 3500, checked the temp and it was 180 and running fine.
I pulled into the Marina and shut-it down and when i went to restart to put it on the trailer it sounded like a old Nova 6cylinder with a exhaust leak......Took it in and come to find out I had blown the Head gasket between cylinders 1 & 3....and we are now looking at some $$$$ that couldnt have come at the worst time....How screwed am I....Please advise ASAP!

Well, when the engine is apart you really need to remove both heads and have the valves checked and resurfaced/replaced as necessary ( a valve job) which is normally due at about 300-350 hours. It would also be a good idea to replace all the valve springs, they crack them more than most other engines. Otherwise the bottom end should be good and you can get another 500 hours from it. You might also have the tech check the lifters, I had several bad when I did my 350 hour HP500 EFIs.

Approx how much money did take to rebuild yours if you dont mind that I ask....What was wrong with the lifters???? I was told that my CMI headers didnt have any discoloring so apparently it didnt get too hot....Do you know if there were any problems with the 500 EFI head gaskets....
Thanks for the info....

Made some phone calls today and "WOW" this is going to hurt! $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$

Where do you live?? There are some good guys out there that wont roll you up. But you are going to spend some money, money well spent if done right.

Boat is out in the havasu area...partially torn down....

Dude 535 hours on stock 500efi head gaskets is a good run. If you do it work your self you could be back on the water for $300 or so if you just do new gaskets and have the heads checked n decked.
If it were me I would have the heads rebuilt and not have to worry about a spring braking.
Even paying someone to do all the work I would think you should come in under 2k to have the heads totally rebuilt. That is a lot cheaper than dropping a valve into the motor. You ever price a fresh 500efi long block?

with over 500 hours on it might be worth it to pull motor, and go though it. Would be a waste of money if you did a vavle job and head gasket on it and the bearings where hurt, and it went further south. There are some pretty good guys in Havi, Chris at Prestige, Flat Top, Gary Kinkad, Absolute, AJ, (who ran Savage).
You are going to spend some money, and it is the worst time of year, but.. a little bigger cam and and ecu reprogram...

Dude......That is why I am all over these forums trying to get some ideas because i dont have $35,364.22 laying around for a brand new motor....Those days are gone...if you know what i mean....I will agree with you that it was a good run (535 hrs) and I love the motor. That motor would push my 5500 lb boat around with ease!!! it would almost get me to 70 mph...Oh yah I forgot to add that the motor was almost 13 yrs old...I have a quoted price of $8,500.00 to completely go thru the motor and replace everything except for the Block, Heads (They will be decked), rebalance/repolish the Crank, break it in on a Dyno and Dyno test it....I am just trying to justify to myself coming up with that kind of $$$$$$
Any opinions......

Wheres the boat? Might be over kill to replace pistons?? wont know till you pull it. Find someone that is honest and competent. you only want to do this once... There are some good guys... then not so much..