80's 1150 - Water psi port and pitot line

[KING6]

Can anyone confirm either of my questions. Im hooking up the Speed gauge to my boat ..previous owner never hooked it up. I know how it works.. the gauge works. I dont know where it hooks to on the motor exactly. I found one small hose on the engine that appears to run down to the lower unit, I can confirm it runs to the lower part of the motor. This is the hose labled Pitot line? in my pic. the end was just open and it ran to a part of the motor housing that has a hole going to the outside. I Think it could be a vent for the lower unit. I tried blowing air pressure into it and I get no air leaking form anywhere. Its also a rubber line..not plastic like I read in many searchs I did on here.
On the lower unit there is a small hole that has a bullet shaped indent leading into it.. I figured this was the pitot pickup. I tried blowing air in there as well and I get nothing for air coming out somewhere. I shoved some wire into there and grease was on the wire and coming out the hole a bit.
Or maybe I got this all wrong and my motor doesnt have pitot in the lower unit:facepalm:


Also picked up a water pressure gauge. This is a simple hook up but I want to make it right, not by hooking up the teltale line because thats not going to be accurate. So the other label in the pic, water psi?.. that hose is connecting to a port on the top, in the middle, and on the very bottom of the motor. Is this line water pressure? If so Ill just T It. simple enough. If not, where else is there a hose, or fitting to T/connect to?


Thanks for your help!

 

[mr 88]

Re: 80's 1150 - Water psi port and pitot line

To the best of my knowledge the ftg for the water pressure gauge is located between upper spark plugs. Should be a brass plug there that you would remove and then replace with your water psi ftg... Your speed O line sounds like it is clogged up,providing someone has not swapped out your lower unit at some time with one that does not have a PU. Hand held GPS work great without the hassle.

 

[Chris1956]

Re: 80's 1150 - Water psi port and pitot line

King, Some inline 6s have a plug on the head's waterjacket, some do not. If your motor has it, connect the motor water pressure gauge there. If you do not have one, remove the plastic elbow for the telltale and screw a brass tee into the water jacket. Now use one side of the tee for the pressure gauge and the other for the telltale. Inline Mercs have only a few PSI, so get a 0-15PSI gauge if you can.

 

[79Merc80]

Re: 80's 1150 - Water psi port and pitot line

Also, I noticed that your Merc is pre 1979 as it doesn't have the ADI ignition (Had a distributor) I believe 1979 was the forst year that the lower unit had the speedo pickup built in. Every one I have seen has the speedo connection just above the lower unit.