2000 Mercury Optimax 150. 645 hours. Recently had engine serviced. Waterpump was replaced and oil and pressure line from external oil tank were replaced due to dry rotting. Engine running fine with exception of poor water pressure at drop off. Upon delivery post repair I operated the engine approx 20 minutes with a portion of that at WOT from the ramp to my slip. Everything was normal. Returned a couple of days later to take the boat out and engine began running rough and smoking white while I was idling out of our cove about 10 minutes after start up. I also started getting the 4-beep warning. I shut the engine off, googled what the 4-beep meant, and found the most common cause is low oil level in the onboard oil tank. Checked the on-board oil tank and checked external aux tank as well. Everything looked normal except the onboard tank oil level was about an inch below the top of the tank. Started engine back up and it operated fine, no rough running, or smoking. To be safe I returned to my slip. Engine ran approx 10 min with no issue. Shut it down until I could further investigate later. Returned a couple of days later and the engine would not turn over! It appeared seized! Also, when I trimmed the engine down to start it a cloud of oil appeared around the prop. The service dept towed the boat. Upon investigation they found that the tech got the oil line and pressure line backwards when splicing the new lines to the engine. Service dept now says the mistake has been corrected, they replaced the spark plugs (issue caused excess oil in cylinders?), and they lake tested the boat. Engine is now running fine. My question. Should I be expecting any long-term effects from this mistake?
