Where did my oil go?

[TheGriz]

I have a 2007 SX230 HO and have owned it since 2017. I am on my 4th starboard engine and original port engine. The original owner replaced ithe starboard engine the first time with an SBT block in 2015 and it lasted until 2019. I replaced it with another SBT engine, but that brand new engine only ran for 30seconds and failed catastrophically. That engine was replaced under warranty i and has about 15 hours on it (I had a kid and it didn't use it much).

7 days ago, I started prepping the boat for the summer (changed the oil, replaced the exhaust blowers, and replaced the batteries). I vacuumed out 3.5-4qts of oil from both engines and refilled both according to the dipsticks, roughly 4qts in each. The starboard engine was hard to start on the hose, but eventually started. Port engine ran like a champ.

I added about 45 gallons of fresh gas and got out on the lake. On the lake, the starboard engine was hard starting, but eventually started, port engine ran like a champ. As soon as I would chop the throttle, the starboard engine would die. I ran the boat about 5minutes between 7-10k RPM, chopped the throttle and the starboard engine died. I had a couple more attempts to start the engine, but it never ran for more than a couple seconds and then it never started again. Engine would turn over just fine. I did make the mistake of trying to run higher RPM (less than 5min) on just one engine, only to learn here that it can cause water to enter the exhaust of the other engine. I tied up at a dock and took a crack at it the next day with fresh eyes. The bilge was full of water. REALLY FULL. The bilge pump removed it all.

The next morning, The bilge was empty, so I am pretty sure the bilge was being filled with coolant water. I checked the plugs and they were fouled. Replaced them on but it still wouldn't start. I made my way to my trailer on one engine running slowly, in no-wake mode. The bilge was really full again, taking forever to drain through the plug.

Got home, started by checking the oil to see if it was milky, only to be surprised that there was NO oil in it all. Put a camera down there just to be sure... NADA. Did a compression check on each cylinder (200, 200, 210, 210psi).

1. Where did my oil go? (Hoping now that it never restarted because of an oil sensor failsafe)
2. How is water getting into my bilge?

I was hoping to get some advice before refilling with oil and checking for leaks. The engine compartment looked about the same before and after (it was a bit of a mess from multiple engine changes).

 

[Bruce]

Is the oil filter loose or damaged? Is there a crack in the block? Either of those should like the oil into the bilge.

Did the oi exit out of the exhaust.

You might consider refilling with oil then running on the hose to see where the oil is going. I would email SBT to get their thoughts in writing first.

 

[dgfreeze]

Continuing on with what Bruce said, is there any indication of oil under the engine? If it leaked out and dripped down, you should be able to see a slick of some kind. It pretty much has two places it can go: External leak that drips down, or getting mixed into the exhaust. Mixed into the exhaust is a two part possibility, in that it could be mixing with the cooling water, or getting burnt in the combustion chamber. (so you could call it three places) If there's another possibility, I can't think of it right now...