1996 Mercury 150 Water Pressure test point

[bobdec]

Engine 1996 Mercury 150 HP Offshore SN 0G337407 . The Service manual says there is a plugged gray hose that can be used to test the cooling water pressure. Hose/fitting can also be extended to an external (dash) WP Gauge . I purchased a gauge and appropriate hose this winter in preparation to install a dash setup. However now I can not find the referenced hose. Looking for help finding the hose or a test port.

 

[wired247]

Re: 1996 Mercury 150 Water Pressure test point

You can drill and tap the divider plate or drill and tap the top of the head where it meets the block for an 1/8" NOT fitting to attach your hose. .

 

[Dukedog]

Re: 1996 Mercury 150 Water Pressure test point

You can drill and tap the divider plate or drill and tap the top of the head where it meets the block for an 1/8" NOT fitting to attach your hose. .

That way will work but tha normal way is this.........

There is a hose coming from tha top of tha motor (right behind tha flywheel) that goes down to tha poppet right under tha switch boxes. Just put a "T" in that hose at tha top of it where it comes outta tha block. That's tha easiest

Gotta ask 'bout this gray "test" port/hose though. Have ya got tha manual number and page number? OEM Merc. or after market manual? Can't remember ever seenin' anything like that but hell I'll old and forgetful...............

 

[sam am I]

Re: 1996 Mercury 150 Water Pressure test point

 

[wired247]

Re: 1996 Mercury 150 Water Pressure test point

The poppet and thermostat "T" method gives terrible , erratic readings as it pressure spikes or drops to nothing as the poppet and thermostats open and close. Don't do that. The factory gauge connection point is on the exhaust divider. You get good reading off the top of th eheads or at the top of the block if you are not tied into the thermostat, poppet system.

 

[Dukedog]

Re: 1996 Mercury 150 Water Pressure test point

That "tap" point has absolutely nothin' ta do with stat or poppet. Thats tha first place ya get access to tha block from tha pump. Water enters at tha bottom of tha block and travels straight up to tha point................Look at your dia. Know ya got one.

 

[wired247]

Re: 1996 Mercury 150 Water Pressure test point

It does water hammer in that line from the poppet action and it does give a more stable and accurate reading of the blocks cooling pressure if you take a reading independent of the thermostat/poppet system.

 

[Dukedog]

Re: 1996 Mercury 150 Water Pressure test point

Look at it. Its AHEAD of everything else in tha coolin' system. Its even ahead of tha divider plate. Poppet/stats have NO bearing on it what so ever. If it was necessary to read it somewhere else it would be like tha HP stuff and already have tha openings. Tha HP stuff is different because tha coolin' system is different. That's tha only reason. Go to any other board and ask 'bout a tap point for a production motor and see what ya get........You any kin ta Schaffer?

"calf rope".

 

[wired247]

Re: 1996 Mercury 150 Water Pressure test point

Its ahead of everything else in the cooling system but its still in the same line as the poppet. It gets water hammer. Ive had a line hooked to that point, to the heads and to the main chest via the divider plate. The most stable reading comes from the chest. The heads are almost as good but that spot above is jumpy with a fast gauge. Its OK at high speed but the low speed readings suck when cold. 5 minutes with a drill and a tap.

 

[Dukedog]

Re: 1996 Mercury 150 Water Pressure test point

That point is more than fine ona production motor being installed by tha normal boat guy but wouldn't recommend to anyone that's not known ta start drillin' any holes anywhere on one a these things. Not unless I was standin' there with my finger on tha spot. That's my concern..........

 

[bobdec]

Re: 1996 Mercury 150 Water Pressure test point

Without knowing exactly where and what depth to drill and tap, the Tee off the hose to poppet may be the way to go. I'll update with results..

Dukedog, I have a SM I downloaded from the internet.. doc # 90-824052R3 dated June 2002, below is a cut past from page 4B-8. The more I look at the cover page it does seems to mention all but my 150 XL Offshore.

Water Pressure Check
Water pressure may be checked by attaching a test
pressure gauge to the top of the engine block.
A water pressure line (GRAY colored) is provided
that exits at the front of the lower cowl. A dash style
gauge may be connected to this line to register water
pressure.

 

[Dukedog]

Re: 1996 Mercury 150 Water Pressure test point

You will be fine with it that way. There are hundreds out there workin' just fine. No sense in re-inventin' tha wheel on production motors.

Must be for something other than tha "normal" 2.0, 2.4, 2.5 V6. That's tha ONLY motors I do............

Seloc is not to shiny for V6 Mercs......

 

[wired247]

Re: 1996 Mercury 150 Water Pressure test point

Its not that difficult. See where that cutout is pretty much centered between those 3 holes on the port side of the exhaust divider up top. Theres all kinds of room behind that plate in the jacket . You'd have to be TRYING to drill into the exhaust chest. The port side is wide open water.