Water pump pressure on 4.3 Mercruiser Alpha One Gen II

[dontask]

I was wanting to install a water pump pressure gauge to indicate what my lower unit pump is putting out. Does any one know what the range of pressures are from this style cooling system (to the thermostat)? I had a water pressure gauge on two of my outboard boats and they work great. I can get either a 0 to 15 psi gauge or a 0 to 30 psi gauge. I prefer to use the 0 to 15 gauge but don't want to peg the gauge at high rpm's or when the thermostat is at a closed setting.

Teleflex and Faria have 2" marine water pressure gauges with all the needed hardware. The only issue I need to adapt is installing NPT threads to the thermostat housing for the water tube fitting.

 

[180shabah]

Re: Water pump pressure on 4.3 Mercruiser Alpha One Gen II

Pressure won't rise dramaticly with the thermostat closed, water will be diverted straight to the manifolds.

I dno't think there is a pressure spec, so we will have to wait for someone who has already done this.

 

[cooter2506]

Re: Water pump pressure on 4.3 Mercruiser Alpha One Gen II

I think istead of a pressure guage you could put a flow meter on it. I dont think there is alot of pressure there. But a flow meter will tell you there is water flowing.

 

[HT32BSX115]

Re: Water pump pressure on 4.3 Mercruiser Alpha One Gen II

I think that's a great idea!

I have been thinking about putting one on my closed cooled system (15 PSI gage) but putting one on the raw side would be a pretty good idea too. I think you could get away with a 15 PSI gage since there really little or no resistance in the system. (until your risers start to plug.....then I'll bet the pump could put out more than 15 PSI)

Another way to do it would be to use an engine oil pressure switch. A lot of them only take about 3-5 psi to open...... that way you could put an "idiot light" up front that would come on if you lost your raw pump.


If you really want to know, break the line from the raw pump and put a PVC fitting in there, connect a gage and measure it! Inquiring minds want to know too!!


Cheers,


Rick

 

[Johnny_Law]

Re: Water pump pressure on 4.3 Mercruiser Alpha One Gen II

Unfortunately I never checked before replacing my impeller day before yesterday (my first). But I am now getting about 7.0psi at 2800rpm. It goes up with RPM at Idle it is about 0.6psi. The low end at idle is comparable to what it was with the original impeller as I do check it when on the muffs.

I suspect too much is an indication of a blockage and a low pressure an indication of a bad pump.

Anybody have numbers on their raw water pump pressures?

2007 4.3L MPI I/O