1996 Mercury 150XL water leaking inside the cowling

[mjcarbo]

I recently purchased a 150XL Mercury. The motor runs well. There was a good stream out of the telltale but if I trim the motor a bit too high or in moderately high waves, the overheat horn goes off.
I started checking the water system. Running with muffs I noticed a trickle of water inside the cowling on the starboard side at the bottom below the switch block. I believe there is a poppet valve located there. There is a T valve at the top of the cylinder heads with a small water line going to that area. the water line didnt seam to be attached to anything because it came out easily with a light pull. There is a a strong stream of water coming out of that line and there is no flow out of the telltale.
I can't find where this water line is supposed to go. The end of the line has a clean cut, It does not appear to be connected to a fitting but it must go somewhere. Now when i replace the water line in the area, the water leakage is much more then before and there is no telltale flow.
I bought a Chlymer service manual but it does not have much detail on the cooling system.
Can anyone shed some light?

 

[Faztbullet]

What you have circled is the feed line for water pressure gauge..If water is coming out poppet vent it time to replace it.

 

[mjcarbo]

That is the water line going into the area of the poppet valve.By the way, line is the same size has the water line going to the speedometer The line was just loose somewhere around the poppet valve. Once I moved it outside of the cowling there was no more water leaking inside the cowling.
It could be a pressure gauge supply line but its too much of a coincidence that the telltale flow stopped at the same time. And the last time I ran the motor (last weekend) it was to flush it out using the muffs. The telltale flow was very strong and it had been consistently strong.
I see a heaver supply line going into the poppet valve with no water leaks.

 

[leonreno]

Look for a line that cut line was connected to with an in-line coupling, that line would go to the pressure gauge. And yes, speedometer and pressure gauge tubing is the same as they both function off water pressure. It may be hidden under motor or if that motor came from another boat recently the line may not be there, in that case I would recommend installing a new pressure gauge, one of the most needed gauges on the motor. Tell tail water does not flow until after the thermostats open, usually 30 sec to a few minutes depending on water temp. Maybe why you didn’t see flow when on the muffs.