Water Pressure Install

[Mikep79]

I have an '04 225 Vmax Hpdi. I am trying to install a water pressure gauge on my boat. I have already bought a Faria H2O gauge and have bought the tubing and nipple screw. First, the tubing and nipple are not Yamaha parts, will that make a difference or are these i've bought going to be o.k.

Next, I have searched on this board, but I still cannot find where the nipple goes on top of the head. If anyone has a pic that would help a lot. I've looked on top of both heads and have two bolts that look identical with one having an orange paper washer under it and the one on the other having a pink (probably was orange) washer under it. I also have something screwed into the top of the head right next to those bolts on the right side of the engine and it has wire coming from it, is this the temp gauge for the overheat alarm. If it is, then there is not a like connection on the left head.

A pic or any help would be appreciated.

[Charles Prestridge]

On my 150 vmax carb, the 14 mm bolt that was removed for the water pressure hook-up, had the orange washer underneath the bolt. There should be the same bolt in the same place on both heads. You can use either one of these bolts. The experts will indicate that you should pick the bolt that is the furthest away from the intake. This would be so that you are measuring the pressure (after the highest pressure drop from traveling through the water passages in the engine). Some will say this is the port side and some will say this is the starboard side. Pick one and install your fitting in the head. Run the tubing from that fitting to the water pressure gauge.

You do not have to purchase the fitting from Yamaha, but it does have to be the correct thread size for the engine block/head.

To double check, you can have the hose disconnected from the gauge and then crank the engine. Water shoot come out of the end of the hose (pretty good). Point the hose over the side of the boat if possible. At idle, it will not come out like a flood, but it will be enough to tell the engine is running.

Good luck.