To boat motor experts: Mike or Gary or Matt or Spanky

My son's XR4 Merc 150 hp is a 1988 model-I just noticed today that water was coming out a rectangular port on the aft left side just below the cowling-the telltale was also producing a good stream of water. Is this normal right after start before the thermostat opens or do I have a problem? The Seloc manual does not even mention the two ports. The engine is running fine and the temperature seems to be within normal limits on the gauge. Maybe i am just gunshy about overheats.

That means there is trash in the poppet valve or the poppet valve spring is weak allowing water to bypass the valve inturn the block will not warm up as quickly as normal....OPTI

Is it hard to change the poppet valve??

The poppet assembly is on starboard side, back and low on the power head with 4 - 5/16ths bolts holding it in place. Would have to look at it to tell. I know you have a 3/8ths water hose outlet coming out of the exhaust plate close to were you are talking about that tee`s into the hose from the thermostats, then going to the pee fitting. Not shure about the port as Merc has so many different set-ups.

I see nothing that looks like what you are talking about on the bottom of the power head-one fitting comes out on the left and goes to the pee stream but nothing that looks removable for easy replacement. At the top of the "pee" fitting there are 2 "y"s that come out of the powerhead but also don't look like they could contain a poppet valve....I will keep looking-I know Merc has a lot of variants

Ok The poppet valve is not actually on the powerhead it is on the exhaust plate it is on the strbd side of engine your poppet does not have a hose running from it to the top of the block. It looks like two circles one small one large and the large one has a weep hole in it with for bolts securing it to the engine....OPTI

Opti, I think he's talkin 'bout tha small exhaust reliefs on tha back of tha downhousing.'88 should have those.....

If thats what your talkin' about its normal. It gives tha exhaust some relief at idle cause tha tuner is covered with water. Should have a little exhaust mixed in with it.

I believe you are correct-seems like an exhaust and water spray mix-never had noticed it before-thanks for everyones help

Opti the poppet is in the block where stated. Sometimes hard to see behind the bottom of the bracket mount for the power-packs. Went and looked at a 1989 XR4 and it has no exhaust reliefs. I really do`nt think he has a problem. Some Mercs have relief hole and were put in the center section to help reduce problems with loading-up at slow speeds, mainly idle in gear.

"Brain farts" come a lot more regular with age. Mine are gettin almost continous..............

Your right TL I've been working on these dang things to long and they all run together I have a brain fart aleast once a week getting close to 50 so they are coming more often HAHA ...OPTI

The poppet valve doesn't have to be open for water to exit the rect. ports below the cowling. Merc. usually doesn't have a tail-tail until one or both thermostats both open. Water usually comes out rect. ports when the motor is deep in the water, poppet valve open or under full throttle on top of the water. As long as motor is running cool, no reason to be alarmed at this point, but servicing cooling system is recommended annually and at least every 2yrs. Courtesy of Cary's Mobile Marine Services.

I knew the thermostats had to open before the telltale would have a stream so i think that his what alarmed me when I saw water spitting out with exhaust. Thanks for your response-i had the cooling system checked in May and he said everything was fine-just nervous i suppose.