Water Pressure
 

Where are you guys tying in for your water pressure gauges. I have a Livorsi mechanical water pressure gauge, its on a gen 6 502 mpi, and curious where people were connecting the tube to the motor for a good reading?

Ayuh,... Tappin' into the T-stat housin', where the temp sender is, will give ya Block pressure, which is the important point to Me,...

I put mine in place of one of the block drains...

They're tapped into the T-stat housing for the 6.2 MX Mercs in my boat so I guess it should work for your 502 too. I have tubes installed as well to back up the SmartCraft electric with manual gauges.There are plugs on the right hand side of the T-stat housing where to install sensor or mechanical fittings.

http://www3.telus.net/spectrasonly/M...06,2%20L%20MPI

Yea I don't have a factory t stat housing as I have a crossover kit with bypass. I am going to take a better look around, as someone told me there should be a plug in the intake right there I could use. I am not getting much reading at all out of the drain hole in the block, but I am flowing plenty of water

If you are running it on a hose, you won't see more than a few psi. Might see 5 psi with reving it.
Readings from the block or intake should be the same.

Block drains clog up with junk and won't read anything on the gauge. T stat housing or intake is a much better place

Yes, they will clog. That's where mine is connected and it fills with sand and junk.

Since I have to remove the hose to drain that side of the block anyway, I break the connection to the gauge under the dash and blow it out with an air hose as part of my winterizing process.

Mine are the block drains and never a problem. I don't beach or shallow water, so never an issue.
On a different thought process, when your block drain connected press gauge do stop working do to sand or whatever, you know it's time to flush your block.

Now the question that begs is what pressure do you want? Flow is more important of course and is often inverse of pressure (such as if you had an outlet obstruction yielding very high pressure, low flow and overheat) A fire hose has no pressure at the end but great flow. If you plug the fire hose then the pressure at the end will go high as flow goes to zero. Not as simple as high pressure good, low bad. Flow. An interesting puzzle.

20-25psi at WOT is a good number to shoot for

Ok so port on front of intake is where my water temp sender is. So block is the only location, Water pressure gauge and all the tubing were installed over the winter in a freshly redone motor, and I am just not reading much of anything. when I rev the needle will jump a little then go right back down, and running I don't see anything really. Like I said motor is fresh, impellar is new, gauge is brand new livorsi gauge, all tubing is new, and no overheating at all with plenty of flow out of the exhaust. We are going to take it apart 1 day this week. I have a crossover kit with bypass, and running a thermostat. Could that effect the pressure I see?

Running on the hose or in the water? On the hose you won't see any pressure, and only a couple pds with a quick wrap of the throttle

Are you running it in the water or on the hose???
If its in the water and you're not getting any or very minimal readings, you probably have a kink in the tubing.

A way to solve the puzzle is use a hose from the intake manifold and dump the excess water out thru the transom. To get some/slight water pressure, we tapped and screwed a restrictor into 90 fitting out of intake sized to achieve the targeted water pressure. We use a 2-stage water pump and hold about 10 lbs water pressure in the intake with a water temp in the 100-115 degree range....no thermostat used.

So I am replacing my current crossover with a Hardin (Bypass), reason being is my current setup wont allow me to run a T-stat because no water could get to the manifolds/ risers until the stat opens, with that said, I see allot of posts here saying they are running gauges to the top of the housing, if so would you not see any pressure until the stat opens?

Both running on the hose and running in the water. Seems to act that same in both situations. I know I am flowing plenty of water, as there is plenty coming out of the exhaust, water temp, and oil temp are low as the water in the river and bay is on the colder side this time of year. So it leaves me to think either 1. The crossover with bypass effects the water pressure, or 2. there is something wrong in my gauge and tube set up. Whether that be the hose is pinched or clogged somehow or something is wrong with the gauge itself even though its brand new. We were out in my buddys 38 AVS sunday, he has cross overs with out bypasses and both his water pressures were registering fine, right about 20psi. So wonder if the bypass flows too much water compared to the flow through the block?

Simple way to check guage. Connect a new tube and put 20 psi of air to it.
I doubt it is the guage. The tubing kinks easily and that is most likely the issue.

Ok, yea that was our plan to pop it with some air and see. I will also check the line for any kinks.

One of my gauges was a little lazy last year - would show some pressure, but quite low. ...then would hold pressure after engine off.

I flushed with compressed air - and this nasty, smelly, gunk came out!!

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Update: A while back the guy who does all my work had a buddy with a fountain that was having a overheating issue. He had a crossover with bypass and thermostat, and even though his water and oil temp was getting hot, the exhaust was nice a cool. Well they figured out that with the bypass hose being very large on these kits, it would just flow most of the water straight through the bypass and out of the exhaust. So he put a washer in the bypass hose right against the tstat housing to restrict the flow and it fixed the over heating. So we did the same on mine, and water pressure jumped right up, too much actually. We are playing with different sizes to get the pressure right. Basically the bypass on these kits flow too much water, and doesn't provide much resistance to push water through the block with much pressure, so the water just takes the path of least resistance and flows straight through the bypass and out of the exhaust once you have any kind of pressure in the block. Is this not a common issue with people running the crossover with bypass and tstat?