Steam from pee hole

by Rudie
(Secunda, Mpumalanga, South Africa)

Hi there.

I have a recently rebuilt 1969 Mercury 1000 Thunderbolt engine. The motor runs fine and very smooth and fast and water is coming from the pee hole. It is litterally so strong flow that I geuss it will shoot about 6 yards far if turned sideways. There is no other place where the water is coming out of but the pee hole. There is 2 water pipes coming from the engine manifold side and then they connect to one another and go to the pee hole.So what happens is that after only 5 minutes in the water the pee hole water stream gets so hot that it littery burns the crap out your hand when touching it and then suddenly there is no more water coming out of the pee hole but only steam.Which by my understanding means that the water circulation through the motor is not sufficient or restricted due to all outlet pipes connecting to one another and the out to the pee hole.
I have a new impeller but did find a small crack on the lower unit of the water pump on the outside of one of the bolts threads. I have no idea of where water must come out of on this engine and the guy that worked on the motor doesn't seem to be know where to look also.
Any suggestions.