Yet another problem with my 3.0, Please help

[airtime63]

I have an 87' 3.0 mercruiser with an Alpha One. I just had my water impeller redone along with everything else for the stern unit water pump redone. The impeller was fried and didnt cool the engine, but I shut the engine down quickly before too much damage could occur. I ran the boat one time since the work and she ran great, not a problem the whole time out (a weeks worth of boating on vacation). Also had her tuned up, new starter, new bellows, new gimbals, points, plugs, and wires.
I wanted to take the boat out one last time for the season. At home I started the boat (started right up) and it didnt expell water a hard or steady as usual from the water outlets. The engine then began to smoke (white smoke) and sporadicly coughed water from the exhaust outlets near the transome. However the engine continued to run great, it didnt get real hot as if overheating.
I am losing my patience with this 2 year long project boat. I have had her on the water only that one week in two years. I need some more experienced help, what could it be? Where should I start looking, impeller again, exhaust unit? i dont know where to start. I have a great hull, but im starting to not trust my powerplant. I was told when she was in the shop for the other problems, that the compression was somewhat low on one cylinder. Also, could old gas cause these problems? She sat without Staybil for about 2 months.Thank you in advance

 

[stevieray]

Re: Yet another problem with my 3.0, Please help

However the engine continued to run great, it didnt get real hot as if overheating.

How long did you run it? What did the temp gauge look like?

 

[airtime63]

Re: Yet another problem with my 3.0, Please help

I ran it about 15 minutes and she purred. The temp gauge needs to be replaced and sticks, that is no help at all. I kept feeling different components of the engine and it was not getting hot, the whole unit was running cool to warm. Thanks

 

[Don S]

Re: Yet another problem with my 3.0, Please help

First, get the gauge fixed.
Second, you need to find out where the flow stops. Locate the hose that goes from the transom shield to the thermostat housing and disconnect it from the stat housing. Hook up the muffs and start it up. Only run it for a few seconds to see if you get a good flow of water. That will tell you if the pump is working. If that is ok, then I would be looking at the exhaust elbow for being plugged up.

 

[airtime63]

Re: Yet another problem with my 3.0, Please help

Do you have any idea what the white smoke could be coming from. Could burning two month old gas be creating that problem. Thanks in advance.

 

[Don S]

Re: Yet another problem with my 3.0, Please help

It's steam. What little water you are getting thru it isn't enough to keep the exhaust gasses cooled down. Once you get decent water flow, it should stop.