Water pressure gauge. install ?

[PARADOX]

Thinking about putting in a couple water preassure gauges.
Where do I put the sencors? Can I use "oil pres" gauge?
And the big Q.. . do they actually do any good?

Thx
P

[in the pink]

Oil pressure guage is too high, water pressure is only 15 lbs or so. You have got to figure if you see water pressure dropping due to a faulty impeller or something, you can do something about it before temps ever start to rise. I have them and like them. I just run a tube from my intake manifold right at the thermostat housing.

[DAREDEVIL]

Water press is in deed very cool and good, i take mine off the top of the thermostat housing !!!!!

Use a Gaffrig ,,,works perfect .:cheers2:

[gcarter]

Well, let me ask a slightly different question.....
I have a transom pickup and a crank driven pump. When the boat is finished, it will have closed cooling.
With this setup, where's the best place to install the sensor?

[offthefront]

Prob on the pressure side of the sea pump ...or maybe on the exit side of the heat exchanger ...this is only going to tell you if you have sea pump failure or a clogged heat exchanger .......m

[bajabob 718]

some oil cooler have a brass drain plug on the bottom . mine does

[DAREDEVIL]

If u have a sea strainer ,,thats where i would put it in the case of a closed cooling .:seeya:

[gcarter]

I had some experience w/another boat set up similarly. I had hose leaks from over pressure. It seems the pickup almost has a pitot effect.
Thiis time I want to know what's going on annd have the ability to add a relief valve if I need to.

[DAREDEVIL]

I had some experience w/another boat set up similarly. I had hose leaks from over pressure. It seems the pickup almost has a pitot effect.
Thiis time I want to know what's going on annd have the ability to add a relief valve if I need to.

Then a small Stainless marine Sea Strainer would be perfect, has a press relieve valve on it and a place for a water press sender ! :cheers2:

[Ted]

I had some experience w/another boat set up similarly. I had hose leaks from over pressure. It seems the pickup almost has a pitot effect.
Thiis time I want to know what's going on annd have the ability to add a relief valve if I need to.


IIRC Jim (mobilemercman) posted some numbers a while back that showed a large amount of pressure developed as speed increases, I suspect a lot of people have a bunch of water pressure and don't know it.

[inbetween]

I have mechanical water pressure gauges with the hoses tapped in the drains on the side of the engine. Pressure runs 12-15 psi at 3500rpm. Doesn't seem to go higher than about 18 at WOT. It has been suggested that intake or thermostat housing is a better place to get the reading from.

[38fountainSC]

Mine also come off the block drain on the port side of motor. I believe it is a factory set up from fountain.

[MERPerformance]

Water pressure can vary at different locations in the system. Higher before it reaches the sea-strainer, lower at exiting. My experience has been that the pressure seems to be the same either at the top of the block,say just before the thermostat or at the bottom of the block. If running a closed system, any place after the sea-water pump and before it exits the heat exhanger entering the exhaust.

[MOBILEMERCMAN]

Mercury used to measure it at the block. More recently on closed systems they measure at the oil cooler.

I have measured at the strainer during set up before. Not a good place to measure. There are heavy spikes and air is usually present. The point of a gauge is to recognize what the engine is seeing. So measure at the motor is my opinion.

Having the proper pressure can be a balancing act during set up. Too much can indicate you are dragging too much and potentially loosing speed. Too little you engine suffers.

Ideally you only scoop what is necessary and bleed the air off.

[Ratickle]

Having the proper pressure can be a balancing act during set up. Too much can indicate you are dragging too much and potentially loosing speed. Too little you engine suffers.

Ideally you only scoop what is necessary and bleed the air off.

Any tips on accomplishing this?????

[MOBILEMERCMAN]

Test, test , test.

[HaxbySpeed]

I like the gauge to read what the engine is seeing. I don't like the T-stat housing because you could have a restricted thermostat and have 30lbs inside the engine trying to blow the head gaskets out and only show ten on the exit side. Like others said, for closed cooling the oil cooler is a great spot. :cheers2:

[PARADOX]

Thanks guys. I have no cooling issues, or water flow etc.
Been doing a lot of discussions with Merc Racing and CMI. So this is just some preventive measures.
Both Merc and CMI gave me some insights and I will post them soon.

[US1Fountain]

IIRC Jim (mobilemercman) posted some numbers a while back that showed a large amount of pressure developed as speed increases, I suspect a lot of people have a bunch of water pressure and don't know it.


I agree 100%!

My Fountain has WP gauges and I was pegging them at cruise speeds. Completly stock 502's. Good thing was a saved tons of $$ in fuel since I stayed out of the throttle for most the summer then while trouble shooting.
1 day while letting the wife drive, I cracked the hatch for a peek. Could not believe how much the large hose from the circulating pump-t-stat housing grew under pressure! The Merc relief valves took car of that issue. Now I'm maxed at 20psi.

[Elite Marine]

Let me know if we can help you with the gauges!

Kirk

[Airpacker]

rear corners of the intake where the heads are blocked off is a good place to install them. Drill, tap 1/8 NPT and install fitting. Use a shop vac to grab drill cuttings and grease the tap before using. Using the holes low on the block at a drain can allow rust precipitate to plug your gauge lines.

[old377guy]

I love this board, I file this information away for future re-rig projects. - Jeff

[Pismo10]

I would like a water flow gauge more than a pressure gauge. Flow is what cools the motor. You can have lots of pressure and low flow, like an outlet obstruction. You can also have lots of flow with fairly low pressure. They aren't necessarily directly related. Expensive tho.