Water Pressure Gauge Installation 150 V6

[rla0248]

1982 150hp V6.<br /><br />I just got a water pressure gauge.<br /><br />I think I have located two potential places to tap into the system. Tell me witch is best.<br /><br />Option 1: Hose that goes from the pressure releaf system to the thermostat on the right side of engine. <br /><br />Option 2: There is a plug on top of the engine, behind the flywheel, centered between the left and right cylinder banks. Does this go into the water jacket? If so, would there be water pressure at this point, before the thermostat opens.<br /><br />Witch of the above two (or other suggestion) is the correct spot to tap into the system.<br /><br />Are the water jackets on each bank isolated from each other? It would seem so, since each side has a seperate thermostat.<br /><br />Thanks

 

[KCLOST]

Re: Water Pressure Gauge Installation 150 V6

Here is a pic that shows how I tapped into mine.<br />It's the plug on the top of the engine which is option 2. You will probably have to find the fitting/reducer that will screw into the block.<br />But you may already have the 90 degree fitting that screws into that one... But it is a direct entry/outlet for the water jacket. When you first start up the engine it will take a few to several seconds for the water to get up there and register the pressure on the guage (just so you don't get surprized).<br /><br />

 

[KCLOST]

Re: Water Pressure Gauge Installation 150 V6

Option 1. Doesn't sound very commom to me...<br /><br />And I don't like the sound of having water exiting the t-stat as your water pressure indicator. If the t-stat is closed no water pressure.<br /><br />Unless that hose is a bypass at all times... (I've never seen that set-up), Usually the hose going to the pressure relief cover comes from the plug at the top of the block.

 

[gss036]

Re: Water Pressure Gauge Installation 150 V6

The way KCLOST explains the hook-up is the reccommed way from Telflex instruments to install the gauge. That is the way I have mine installed.<br />I don't think water makes it up to the gauge, just compressed air. I would not reccommed bleeding until you get water there. Then you will be dealing with corriosion under the dash, etc and also the possibility of freeze up in the winter. You are in SanFranciso area, so freezing is not much of a consideration.

 

[KCLOST]

Re: Water Pressure Gauge Installation 150 V6

gss, that's what I meant about the compressed air....<br /><br />It just takes a little time for the air in the block to escape so the water fills the block... Until the air leaves the block there will not be any pressure registered on the gauge.

 

[KCLOST]

Re: Water Pressure Gauge Installation 150 V6

Did you get it installed?

 

[gss036]

Re: Water Pressure Gauge Installation 150 V6

Keep us posted on your results. I am not very knowledable on whether it will reverse the impeller direction or not. Never had that problem.

 

[KCLOST]

Re: Water Pressure Gauge Installation 150 V6

You need to install the pressure fitting into the water jacket as I described...

Going into the hose "after" the t-stats is not accurate in any way as to what is going on in relation to the impeelr pressure....

Tap it into the top of the block, as I suggested..

BTW,, There is no hose going "down" to the t-stats. There is only hoses that exit the t-stats...

 

[rla0248]

Re: Water Pressure Gauge Installation 150 V6

I assummed that the water entered the block at the thernostats, not exit at the block. That is the way that car and truck cooling systems work, so I thought this was the same.

I will change the location tonight. I will need to replace the hose that I tapped into. It looks the same as 3/8" fuel line. Can I replace with that, or is this some special hose designed for water?

I would also like to hook up a temp gauge. The dash of the boat already has one. On the left cylinder head is a blind hole about 3/8 diameter and about 3/4 or 1" deep. Is that where a temperature sender goes? If so, does anyone know the part number for the sender?

 

[rla0248]

Re: Water Pressure Gauge Installation 150 V6

Hi,

Last night I tried to remove the plug. I probably put about 70 lb torque and it didn't break loose. Impact wrench? I would rather not crack the block (if that's possible) trying to remove this plug.

 

[rla0248]

Re: Water Pressure Gauge Installation 150 V6

Have now moved the location of water pressure pick-up to the spot shown in the post by KCLOST (thanks).

Following are pressure readings at various RPMs:

RPM Pressure
600 10
1000 12
1400 14
1600 5
1800 6
2000 7
2500 8
3000 10
3500 12
4000 14

Any idea about what is going on here? Why the sudden drop in pressure at 1600 RPM and the very gradual increase from there?

Recently (within the last 2 months) replaced impeller, thermostats and pressure relief diaphram.

Thanks.

 

[Silvertip]

Re: Water Pressure Gauge Installation 150 V6

RLA -- maybe I misunderstood you but auto engine cooling systems do not have water entering at the thermostat. Water from the bottom of the radiator enters the intake of the water pump, is pushed into the engine, and held there by the thermostat until the operating temp is reached (thermostat temp). When the stat opens water exits out the top radiator hose to the top of the radiator. Its cooled as it flows across the radiator where the cycle repeats. The purpose of the stat is to trap water in the block until operating temp is reached. The stat housing usually has a small bypass port to allow some coolant to flow even with the stat closed.

 

[gss036]

Re: Water Pressure Gauge Installation 150 V6

RLA, that would be your poppet valve opening at 1400 RPM, a little on the low rpm side I think. I would have thought it would open at about 2500.

 

[rla0248]

Re: Water Pressure Gauge Installation 150 V6

Silvertip, I guess for some reason I assumed a wrong water flow direction in both outboards and auto cooling systems. Thanks for the education.

Gary, is 10 - 14 lbs pressure OK in the 3000 - 4000 rpm range? The poppet valve spring looked OK, but I guess it could be weak.

 

[gss036]

Re: Water Pressure Gauge Installation 150 V6

I think that is good for that year motor. My factory manual for my 89 2000 Merc specifices 12 PSI @WOT.
I actually jumped up tp 16# at 5200rpm the other day.