496 ho with raylar 525 keeps blowing head gaskets
 

Howdy boaters, new to OSO. So hoping all you guys can help a brother out. I've got a 06 nordic rage with a 496 ho with the raylar 525ho kit on it. bought the boat this last September and first time out boat got warm and the overflow tank overflowed. Did some tests.and ended up shipping it back to dealer to have repairs done. Turns out head gasket was bad. They fixed it brought it back. Ran awesome first few trips out. Few weeks ago oil pressure gauge started bouncing around alot so I replaced sending unit with no change and this last weekend was runnin about 60 and the boat was getting warm again. Opened the hatch to notice the over flow tank had over flowed again, telling me I probably went thru another head gasket. Mind you this has had less than 30hrs run time since the dealer delivered it back to me. Anyone have any input on what could be going on? Could there be an issue with the raylar kit? Do I need to run different head gaskets? Pretty frustrated at this point that it has to be torn down again considering I've put less than 30 hrs on it since I bought it. Any help would be much appreciated. Thanks all and happy boating. 🤙

did you retune it for the 525 kit?I'd say you are detonating like crazy.

Cometic gaskets?

if the engine was running hot it may have warped a head or the block causing head gasket problems.replacing the head gasket without fixing the root problem that caused the gasket failure the first time will result in another gasket failure.

The HO's dont require a retune. Just a change in fuel pressure. I was told when they "fixed" it they did a valve job and resurfaced the heads. Yes cometic gaskets. And I'm assuming head gasket because this has happened before and that's what the cause was.. I havent torn into it yet, was hoping to get some insight before i did. I'm not for sure if they retorqued the head bolts after they ran it. So may try that first before I tear her down.

Also when I say it got warm, I shut it down at 185° and the beeper goes off at 190. It's got a 160° thermostat in it and runs at 165ish. So I wouldnt think there would be any warping again.

Sierra filter if I'm not mistaken but will check that out.

Blowing head gasket
 

My 496 was blowing head gaskets and pistons, It turned out to be a missed placed 10 micron fuel filter, (causing the fuel to boil and cavitate,) The filter was on the intake side of the fuel pump, we reinstalled it on the outtake side, so far it running well.
Good luck

Was your 496 a Gen VII GM 496 ? or a 4.25" stroked 454 to give you the 496 ? I'll guess the later. :)

SB, if its Raylar, its 8.1/496 Gen VII

Krope, the issues may be related. But maybe they arent. Are the bolts holding the heads down SRP or original TTY? (Torque To Yield) TTY shouldnt be reused. There is a chance the TTY bolts are spent if reused and will stretch. Mostly everyone knows this but maybe somebody didnt.

They are ARP head studs now

He did not mention, thus the question.

Your app is not stock per what you have posted and what fuel system do you have ? I know the 496 in my sleep and the 10 micron filter is a round disc pad filter in the bottom of the gen 3 cool fuel STOCK app and if one has the GEN 2 cool fuel the spin on water fuel seperating filters can be whatever micron rating. There is a 113 micron rated metal fuel canister fuel filter before the boost fuel pump on the gen 2 cool fuels / 496 s.