Re: Drain Plugs on a Mercruiser/Alpha 1
The exhaust elbow on 1989 3.7 is self draining,what needs to be done though is do as Don.S mentions and be sure the a/f is good, you can test the a/f yourself with gravity tester you can buy at Wallmart. The heat exchanger as two 7/16 brass drain plugs on the bottom at the back of the tube.The drain plug at the very back is the raw water side pull that and drain, the plug forward is the a/f side and does not need to be pulled.Once drained put plug back in and disconnect the 1 inch hose at the front of the heat exchanger, and blow air into it, this will push water out of the voltage regulater,then pour some R\V antifreeze into hose until it trickles out from water pickup on outdrive. Next get yourself a 2 foot length of 1 inch hose and place it over barb of heat exchanger (the one you disconnected the first hose from) Blow air into it just the be sure that all water has been removed from H.E, then pour some r/v antfreeze in until is runs out of exhaust port on out drive, remove your piece of hose and connect the first hose you removed from H.E side. I have winterized my fathers 3.7 since 1989 this way without any problems.
