Offshoreonly.com - 496 ho with raylar 525 keeps blowing head gaskets

Offshoreonly.com (https://www.offshoreonly.com/forums/)

- General Q & A (https://www.offshoreonly.com/forums/general-q-20/)

- - 496 ho with raylar 525 keeps blowing head gaskets (https://www.offshoreonly.com/forums/general-q/361687-496-ho-raylar-525-keeps-blowing-head-gaskets.html)

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.

If you were detonating that bad you would probably have holes in pistons. I’ve detonated and gaskets were fine. You said your guessing you blew a head gasket. Do a compression test or take it to a competent shop. You will be money ahead. Good luck.

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.

If it’s another head gasket then quite likely the block or head is warped, and it’s usually the head. If they just popped it off and screwed it back on the issue will continue until someone does some proper prep work.

The oil pressure is a whole separate issue. What brand of filter is on it? Many automotive filters swell up or delaminates inside under marine conditions. If you’re getting any water in the oil from the head gasket that may be a problem.

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