Water pressure gauge

[philbullet]

Where's the best place to hook up for lower unit impeller pressure.?
I tryed on heat exchanger it self but not enough pressure to move gauge.

 

[bman440440]

No Title

easy way is mercruiser part # 863820T1... it has a "bung" for water pressure sensor on the later model MPI engines... that's what I did with my 1997 4.3... works great... they can be found on ebay for around $40

 

[Bondo]

I tryed on heat exchanger it self but not enough pressure to move gauge.

Ayuh,.... Whatcha workin' on,..??

What pressures will the gauge read,..??

 

[alldodge]

Where's the best place to hook up for lower unit impeller pressure.?

The block drain plug

 

[gm280]

Well if you just like gauges go for it. I did the same thing, but after awhile, it was just another gauge that really didn't get looked at much. But it looks pretty sitting there on the counsel. JMHO

 

[H20Rat]

The block drain plug

So i'm pretty clueless on merc cooling systems, but wouldn't that measure the pressure of the circulating pump, not the lower unit pump? Again, not knowing exactly how it works, but wouldn't it be possible to have different pressure readings depending on location, based on which pump was immediately upstream of your sensor?

I could possibly see a scenario where you might suck up a plastic bag and cover the lower unit intake, and your lower unit pressure would drop to nearly zero. The circulating pump in theory would keep pressure in the system until the thermostat let water out of the loop. The block pressure would eventually tell you the same thing as lower unit pressure, but it would only just before overheating the engine.

 

[philbullet]

It's to watch your pressure from out drive impeller.
Like on outboard motor s.
I alway have had water pressure gauge on my outboard to monitor impeller pressure. It's the hart of cooling your engs.
I have a outlet on heat exchanger on outside water flow but it's not enough pressure to move gauge neddle.
I may try to add a fitting on staring fluid cooler and try that.

 

[alldodge]

So i'm pretty clueless on merc cooling systems, but wouldn't that measure the pressure of the circulating pump, not the lower unit pump? Again, not knowing exactly how it works, but wouldn't it be possible to have different pressure readings depending on location, based on which pump was immediately upstream of your sensor?

I could possibly see a scenario where you might suck up a plastic bag and cover the lower unit intake, and your lower unit pressure would drop to nearly zero. The circulating pump in theory would keep pressure in the system until the thermostat let water out of the loop. The block pressure would eventually tell you the same thing as lower unit pressure, but it would only just before overheating the engine.

The circulation pump provides next to nothing in the way of pressure, it just circulates water. Pressure is increased due to a restriction. If you have a 100 psi pump and no restriction to confine the liquid, there will be no pressure, only liquid moving. The restriction is done by the entire system.

Pressure exerted in a confined space is transmitted with equal force on all areas. If the pump was pumping and a bag covered the drive intake, the pressure would drop quickly

 

[philbullet]

B man
Thats what iam thinking, I dont have a drain plug on cooler but I maybe can add one and connect there.

 

[Bt Doctur]

A 0-15 psi might work, It`s a question of flow vs pressure. A raw water cooled motor is a free flow system in from the pump, out thru the risers

 

[philbullet]

Yes it's a 0 to 25 psi. Gauge. Gauge work bUT iam not getting much pressure to move neddle from heat exchanger.

 

[alldodge]

Yes it's a 0 to 25 psi. Gauge. Gauge work bUT iam not getting much pressure to move neddle from heat exchanger.

Woops disregard my comment, you said HE in first post but it didn't make it through my thick head until this post.

 

[philbullet]

I tryed to hook up gauge tubing to staring cooler with same results.
Next I'll try a lower preasure gauge.
I guess with a new impeller it still move volume than preasure compared to a 250 hp. Outboard.lol

 

[Bt Doctur]

be lucky to see 3 psi at idle

 

[philbullet]

That s what I am thinking, but that will work.

 

[bman440440]

That s what I am thinking, but that will work.

at idle with my alpha 1 gen 2 pump once the thermostat has opened I get about 0.75 PSI at idle and at cruse of 3200 RPM I get 4 PSI +/- 0.25... and at 4500 RPM I get 6 PSI +/-... BTW I have a 15 PSI gauge ( Quicksilver Part # 79-895288Q02) with raw cooling and new risers so there is absolutely no restriction... it is nice to see what condition your pump is in... after about 250 hours (that's 1 year in my case) I can see its time to change the impeller due to slight pressure drop at idle and about 1 PSI drop at cruse

 

[philbullet]

Yes that what I am looking for, i monitor my outboard but it has alot more psi

 

[philbullet]

Bman, where do you have tubing hose hooked up at?

 

[bman440440]

Bman, where do you have tubing hose hooked up at?

in the prior pic I attached of the steering cooler where the red arrow is pointing is the "water pressure sensor" for an MPI engine... I plumed into there (removed the sensor)... that kit I referenced comes with brass installation fittings/connectors that fit rite into it

 

[philbullet]

Ok thanks