Water prussure guage

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Sugo

Petty Officer 2nd Class
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Nov 11, 2008
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I have a 1990 135hp Mercury Black max. I purchased a Faria water pressure gauge and can't find the location to thread into the block. I assume since it comes with a threaded insert there must be a plug on the block I can remove to install it but can't find it. Or do I need a different fitting and T it in to a water line ? But which one? I have also installed a temp gauge. I am trying to confirm that my heat alarm being tripped occasionally during take off has to do with the way I am trimming the motor. I have replaced the thermostat and water pump and have removed and inspected the poppet valve. Does anyone have a good site to get a list of the correct temp readings and pressures at different RPM'S
Thanks for any help.
 
j_martin

j_martin

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Re: Water prussure guage

On the top of the block, just aft the flywheel, is a pipe plug or a hose fitting that goes down to the poppet on the starboard side. That's where it goes.

It does not go into the tell-tale line.

hope it helps
John
 
C

Chris1956

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Re: Water prussure guage

Sugo, On my '93 Merc 135V6, I ended up tee-ing into the hose that ran from the top of the block to the exhaust housing on the bottom. Don't expect too much water pressure, as you will get a minimal reading at idle and maybe 10PSI at high throttle.
 
capslock118

capslock118

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Re: Water prussure guage

I have the exact engine and was hoping to do what you are doing next season.

Figure it out and let us know what you did - you will save me a lot of time next year :D:p:cool:
 
capslock118

capslock118

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Re: Water prussure guage

Oh but hey - to provide maybe some useful info..

I have also installed a temp gauge. I am trying to confirm that my heat alarm being tripped occasionally during take off has to do with the way I am trimming the motor. I have replaced the thermostat and water pump and have removed and inspected the poppet valve.
Click to expand...

That doesnt sound right to me, not that i'm an expert at all. What is leading you to believe it's the way you have the engine trimmed?

To me that sounds like an electrical problem or something to that affect, like a bad voltage regulator? maybe something else electrical?

I suggest that because it doesnt make sense to me that the alarm would trip only occasionally when taking off. Like I said I'm not an expert but if it was a water pump I would expect consistency and you already replaced the thermostat...


Does anyone have a good site to get a list of the correct temp readings and pressures at different RPM'S
Click to expand...

I have the service manual for that engine, I'll take a look later tonight to see if that data is in there; I can't recall off hand if it is or not.
 
S

Sugo

Petty Officer 2nd Class
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Re: Water prussure guage

Thanks for the response guys. The temp alarm goes off at the same time each trip. I warm the motor up at the dock. Leave the dock at idle take off and run at 3/4throttle and the alarm goes off about 2min later. I stop right away wait 1 minute then I have no problems with it for the rest of the day.??? Once I get the temp and pressure gauge installed I will take it out and hopefully that will point me in the right direction. I guess there is a small chance it might be a temp alarm malfunction, but I hear that is not very common. I guess the temp gauge will answer that. The pressure gauge should help rule out blockage or poppet valve malfunction. If it is a salt build up in the block is there anything that can be done about that? (I have not owned the motor from new, but do flush after every use)
 
C

Chris1956

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Re: Water prussure guage

Boy, that doesn't sound like the thermostats. I think it time to rebuild the poppit. Perhaps it gets stuck at the beginning of each boating trip?


BTW - You might inspect the 'stats. They can get pretty corroded from salt water, and are pretty easy to change. Be careful with the 'stat cover bolts. You do not want to break 'em.
 
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Traceyh

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Re: Water prussure guage

Sugo said:
Thanks for the response guys. The temp alarm goes off at the same time each trip. I warm the motor up at the dock. Leave the dock at idle take off and run at 3/4throttle and the alarm goes off about 2min later. I stop right away wait 1 minute then I have no problems with it for the rest of the day.??? Once I get the temp and pressure gauge installed I will take it out and hopefully that will point me in the right direction. I guess there is a small chance it might be a temp alarm malfunction, but I hear that is not very common. I guess the temp gauge will answer that. The pressure gauge should help rule out blockage or poppet valve malfunction. If it is a salt build up in the block is there anything that can be done about that? (I have not owned the motor from new, but do flush after every use)
Click to expand...

That describes my 88 90HP mariner to a tee. I have the pressure gauge, and it never shows any different when the alarm goes off, I replaced the thermostat, and no difference. I had the poppet out while changing the thermostat, and the rubber was very pliable, and all looked well with the poppet valve. I was assuming that the water pump was going to be the next thing to replace, but I never lose water from the pisser, and never lose pressure on the cooling system.
 
j_martin

j_martin

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Re: Water prussure guage

The cheep klixon switch Murkery uses for an overtemp sensor has been known to lose it's mind.

If the water temp and pressure gauges show normality, you replace the OT sensor.
 
S

Sugo

Petty Officer 2nd Class
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Nov 11, 2008
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160
Re: Water prussure guage

I will finish installing the gauges and get it out for a test this week, see if I can draw some conclusions. I will also post a picture of where I taped into the water for the pressure gauge. Does anyone know the correct heat operating range for the 135hp Black Max?
 
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