Another Blown Engine

[Colvin]

I purchased a used 2018 Scarab 255ID last year with engines at 112hrs and regular service records. I rode the boat twice and on the second ride it was determined a valve broke in the starboard engine at cylinder 2. The boat needed a full engine replacement which fortunately was covered under an extended warranty. Yesterday I took the boat for the second ride this season and the same codes popped up P0300 and P302 except in the port side engine. I pulled cylinder 2 plug and it was damaged at the end like the starboard engine was. I’m afraid it’s the same problem. Why would valves just break? I haven’t even towed a tube or wakeboard with the thing yet. Has anyone had this happen?

 

[fatboyroy]

what octane fuel are you using?

 

[Colvin]

Ethanol free. I believe it’s 91. I always fill it up at marinas in passing.

 

[Colvin]

The two times I’ve put gas in it anyways.

 

[fatboyroy]

i would check if any foreign object is inside the piston hitting your spark plug electrode, if not buy a new spark plug, tighten it then, reverse quarter of a turn in case its getting hit inside piston you have more gaps to avoid it. - Not an expert so you dont have to do this but I couldnt think of anything else to tell you at least you have warranty to replace it again.

 

[Dixemon]

Probably not the valve failing, but rather your timing chain has stretched or jumped a tooth. Allowing the valve and cylinder to collide due to being out of sync. Did the previous owner do a valve clearance check on the motor prior to you purchasing it? If so, they may have knocked it out of time by rotating the cams incorrectly. just a guess.

 

[Maslin]

When I started shopping for boats last summer a local dealer had a Scarab for sale, used with 2 hours. Thought that couldn't be right, 2 hours? Turns out the boat had 50 something hours, the new engine had 2. They traded it in when the engine popped after a few weekends.

They were asking close to MSRP, I didn't get past the explanation for the hour issue. They told me Scarab has the best engine warranty so you don't have to worry about when they blow up...

 

[Neutron]

I purchased a used 2018 Scarab 255ID last year with engines at 112hrs and regular service records. I rode the boat twice and on the second ride it was determined a valve broke in the starboard engine at cylinder 2. The boat needed a full engine replacement which fortunately was covered under an extended warranty. Yesterday I took the boat for the second ride this season and the same codes popped up P0300 and P302 except in the port side engine. I pulled cylinder 2 plug and it was damaged at the end like the starboard engine was. I’m afraid it’s the same problem. Why would valves just break? I haven’t even towed a tube or wakeboard with the thing yet. Has anyone had this happen?

If a plug ends up looking like that, unfortunately something came apart. A piston wont hit a plug if a chain stretches or breaks it hits the valves and will bend them or in some cases break off the valve head and that will smash the plug electrode.

Unless you are 100% sure most marine gas i have seen is 87 and occasionally i see 91
Get a camera down that hole and see is there is debris on the top of the piston