I have a '00 3cyl 2 cycle 90hp Merc OB. Being the anal gauge watcher
that I am I'd like to add a water pressure gauge.

Question is: Where does the sending hose get attached? I see on the
back of the motor is a port with a brass plug in it that looks it
gives access to the water jacket. Currently I have a auto water temp
sending unit in there. Maybe this port is opened when one wants to
drain the motor for the winter.

The other option would be on the port side of the motor is where the
tell tale hose is attached. I could put a T there and attach the
water pressure and tell tale there.

Or maybe there's really another attachment point I havent' found yet?

Question is. Do these access the same opening into the water jacket?
Any reason to use one spot versus the other? I'd like to be able to
keep water temp gauge although I could probably mount that sensor
somewhere else with some extra work.

tks
Don

You can put the T at the tell tale port. That is where mine is hooked up and it
works fine. You are not really looking for an absolute number anyway, just a
change from "normal".
The numbers you should expect to see are about 3 at idle, ramping up to about
17-18 at WOT.

You are not really looking for an absolute number anyway, just a
change from "normal".
The numbers you should expect to see are about 3 at idle, ramping up to about
17-18 at WOT.

tks, I did a little surfing elsewhere and I guess that the tell tale
is on the other side of some kind of pop it valve so if you wanted to
get closest to the water pump then it might be better on the side
where the spark plugs are. However, as you say all you want is to be
able to see an abnormal change (same with the temp gauge) to know that
something different has happened.

I'll play with it this weekend with a fuel pump gauge and then buy a
real water pump pressure gauge later.

tks for the comments.

don