now what???

[alaskanassassin]

My 2004 Merc 200hp carbed 2 stroke recently overheated due to impeller failure. I didn't get an alarm, and my sensor tested good. I replaced the impeller and upper and lower housings, now it is pumping good. I went to do a test drive and started it at the dock, started great, pumped good out the telltale. After a few minutes of idling, the rpm's started dropping, it started smoking pretty hard. I was able to keep it running with the high idle lever on the controls, but the rpm's gradually drop off until it quits. I put it back on the trailer, and pulled it out of the water. When I tilted the engine back down, a LOT of mix oil came out the prop, like 1/2 cup. I was worried about the head gasket. Brought it home and looked at the pistons through the spark plug holes and they are all colored equally, pretty dark. Did a compression test and all 6 cylinders are 120-125psi. What could this be???
The only other variable is I accidentally bought Evinrude XD100 oil and put it in the tank. Would this oil cause those symptoms? All I can think is the oil may be quite a bit thinner than the tcw3 oil and is mixing way too rich, and loading up the carbs and blowing out the exhaust. Does that make any sense? Thanks to all for their ideas! I am going to drain my oil tanks and refill with tcw3 and run it in the yard.

 

[alaskanassassin]

Re: now what???

Drained the evinrude oil, added tcw-3 and pumped up the primer bulb. As I squeezed the bulb, I noticed fuel spraying out a T fitting before my fuel pump. Maybe I was sucking air there before? Put a new clamp on, fired it up and it's running perfectly now, no more issues with the rpm's dropping, and no more heavy smoking or oil out the prop. Sometimes weird things happen. I just wish I had a definite answer to what the problem was. When you are 25 miles out in the gulf of alaska in a little boat, you have to have confidence in your equipment. Next step, water temp and pressure gauges, a kicker install, and a big antenna for my radio! Any thoughts or ideas are welcome.

 

[Fun Times]

Re: now what???

Sounds like you got lucky here. You will want to do a short test run, then recheck things over before you go out to far just to be safe.

Good luck with it.

 

[alaskanassassin]

Re: now what???

Sounds like you got lucky here. You will want to do a short test run, then recheck things over before you go out to far just to be safe.

Good luck with it.

Yes, good advise. I worked it out with a friend to follow me in his boat on a short run tomorrow in case of any more issues. I will be within cell phone range for the next few trips out until my confidence builds. Of course, the past few days have been unbelievable weather, sunny 55degrees, and seas flat as glass. Fish have been practically suicidal, limit catches as I'm at home feeling sorry for myself. At least I'm soon to be back in action.