Engine has never run good at idle and knocks a little

[199675hpforce]

I purchased this boat online sight unseen. Well when the owner showed me how she runs I noticed no water comming out. He had the water hooked up to the exhaust. He an Engineer LOL. Comp is around 107 to 105 across. It was a real low hour engine like new. A short 5minutes without water go or bad? I checkedout the impeller like new condition?

 

[eurolarva]

Re: Engine has never run good at idle and knocks a little

5 minutes without water is not good. Could be a bunch of things. The thermostat may not be opening, the impeller may be damaged even though it looks good, water tube may not be hooked up correctly. Your compression numbers sound low for a motor that is that new.<br /><br />I have had my impeller go out on me and ran my chrysler till it killed and smoke came out the top. I am still using it two years after this happened and have not noticed any problems. If you can still get it to run you need to make sure you are shooting water out the back and make sure you test it on a lake with a trolling motor on your boat for backup with a good marine battery.

 

[roscoe]

Re: Engine has never run good at idle and knocks a little

Are you sure he had water hooked up to the exhaust?<br />How did he do that?<br />The exhaust comes out of the center of the prop on that model.<br />Did he just stick a hose in it?<br /><br />You need to change out the complete water pump, not just the impeller, as the heat generated from running the pump without water may have damaged it.<br /><br />Also change the thermostat.<br /><br />Best to test run in a tank, not on a hose.<br /><br />Probably did no damage to the powerhead.<br /><br />After you get it running again, do a decarb on the engine.<br /><br />Decarb info: http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000016 <br /><br />Then take new compression readings, warm engine, throttle open, plugs out, safety kill switch tripped to prevent damage to ignition.

 

[WhiteHorse]

Re: Engine has never run good at idle and knocks a little

The guy was probably using one of those "Backflusher" things off the telltale and forcing everything back the other way. I shudder everytime I see one on a Force. Those compression readings are definately low for that model.