4.3 MPI over-heat

[kkalsch]

I have 2003 4.3 MPI with a alpha GEN II drive ?was out in the sound yesterday and running at 4000 rpm when all of a sudden the temp went to 200 degrees and the alarm went off. I shut the engine down and re started it ?at idle it cooled back down and was able to run the boat at idle ?as soon as I gave any gas it would start to over-heat again ?..I was able to idle the boat in -any thoughts

 

[svxtech]

Re: 4.3 MPI over-heat

have you done or had any maint done recently? if the case was split to do say an impeller and rtv was not applied to the "dam" between the water pump and the exhaust passage the pump will pull exhaust and cause a high speed over heat, although is probably not the case as the newer dams have not had as much problems with this. I would first look at the water passage tube from the transom to the drive (port side, only hose runs around the outside of the u-joint bellows to the top of the transom housing) if it is dry rotted/cracked can cause this problem. If this boat is run in salt the salt water can build up in the inlet side of the hose you will have to remove the outdrive to see the passage, enough water will pass at idle but not at high speed.