High Water Pressure on gauge

Definitely not a Sabre Hull problem. If anything at all, the only common link here is the 150 4 Stroke Mercury. Cajunhunter 67 has a good idea to post on BBC 4 Stroke Forum. There are some experienced Mercury Techs. on the forum and they will have some insight I would think. European Marine should know if this is a common problem or at least tell you what to check for.

JEH in La wrote: Wheelman I was looking at your water pressure gauge and it is not steady like I have always seen with the Optimax and ProXS. Yours pegs out too so maybe that is a characteristic of the Merc. 4 Stroke. NPHE has owned Yamaha and Mercury ProXS and has never seen the water pressure gauge act this way.
I do know that he can throw a good rooster tail if he trims up too much so I don’t think there is an issue of a trim limiter with his motor.
We just don’t understand why the water pressure is not a steady reading because we have never encountered this with boat ownership going back many years. That’s why he and I think that this should not be normal and would like to solve it if possible.

In the first video it doesn’t do that though, I showed the 2nd video where it was pegged and if you notice the trim is lower than in the first video as the angle of the lower unit affects the amount of water psi. The outboard doesn’t come standard with a water psi sensor, so maybe there’s an issue with the way it’s installed if you can’t get the water psi to drop with excessive trimming even at lower speeds as I don’t think there’s any difference with the design of the lower unit that the non torque master 2-stroke gearcases.

Wheelman wrote:

JEH in La wrote: Wheelman I was looking at your water pressure gauge and it is not steady like I have always seen with the Optimax and ProXS. Yours pegs out too so maybe that is a characteristic of the Merc. 4 Stroke. NPHE has owned Yamaha and Mercury ProXS and has never seen the water pressure gauge act this way.
I do know that he can throw a good rooster tail if he trims up too much so I don’t think there is an issue of a trim limiter with his motor.
We just don’t understand why the water pressure is not a steady reading because we have never encountered this with boat ownership going back many years. That’s why he and I think that this should not be normal and would like to solve it if possible.

In the first video it doesn’t do that though, I showed the 2nd video where it was pegged and if you notice the trim is lower than in the first video as the angle of the lower unit affects the amount of water psi. The outboard doesn’t come standard with a water psi sensor, so maybe there’s an issue with the way it’s installed if you can’t get the water psi to drop with excessive trimming even at lower speeds as I don’t think there’s any difference with the design of the lower unit that the non torque master 2-stroke gearcases.

NPHE is second owner so we’re not sure that the water psi sensor is installed correctly or not. He did not get a manual for his motor either so we just aren’t sure about the 4 Stroke details.
Wheelman do you think the water pressure is actually over 30 psi?
The water psi sensor simply looks like a 1/8″ pipe connection that transitions to the plastic tubing that leads to the gauge. Why is it called a “Sensor”?
The only thing I would do at this point is take it off and see if it’s not partially plugged or something.
Would you please take a picture of your sensor so we can compare it to the one he has?  Thanks in advance.

Wheelman wrote:

JEH in La wrote:

Wheelman wrote:
In the first video it doesn’t do that though, I showed the 2nd video where it was pegged and if you notice the trim is lower than in the first video as the angle of the lower unit affects the amount of water psi. The outboard doesn’t come standard with a water psi sensor, so maybe there’s an issue with the way it’s installed if you can’t get the water psi to drop with excessive trimming even at lower speeds as I don’t think there’s any difference with the design of the lower unit that the non torque master 2-stroke gearcases.

NPHE is second owner so we’re not sure that the water psi sensor is installed correctly or not. He did not get a manual for his motor either so we just aren’t sure about the 4 Stroke details.
Wheelman do you think the water pressure is actually over 30 psi?
The water psi sensor simply looks like a 1/8″ pipe connection that transitions to the plastic tubing that leads to the gauge. Why is it called a “Sensor”?
The only thing I would do at this point is take it off and see if it’s not partially plugged or something.
Would you please take a picture of your sensor so we can compare it to the one he has?  Thanks in advance.

Does your water psi change readings at all depending on speed and trim or is it just pegged at wot? Thread below states 12-43.5psi at wot is normal, hope that helps.
http://www.bbcboards.net/showthread.php?t=575295

Thanks for the help Wheelman. I’m going to get NPHE on here to answer your question with more information than I can give. I’m pretty sure his gauge only goes to 30 psi., so wow, 43 psi is normal?  No wonder it’s pegged out.
This is great information that we didn’t know at this point. All of our experience is Yamaha and ProXS and both of these have much lower pressure.

NPHE wrote: The gauge actually fluctuates from high to low and back to high while running and experimenting with trim. It does not stay pegged out and changes in pressure are sometimes sudden like it loses pressure. This is what bothers me, it just doesn’t seem right. I replaced the BassCat gauge with a new one and both gauges showed the same thing. The mechanic at Cabella’s tried another gauge and it read the same. So I don’t think it’s a gauge problem. I just don’t know if and when my pressure actually does go down that I can trust these readings. Why wouldn’t BassCat install a gauge with a larger reading if 43.5 is correct for this engine pressure?

Sounds like you may have debris causing intermittent readings would be my guess unless you’re running really rough water and surfacing the lower unit. What I find strange is the outboard doesn’t come standard with water psi capability though it’s on more non performance applications that don’t run jackplates than performance bass boats and honestly feel it was designed more for pontoon boats based on the super soft rubber mounts like Evinrude specifically uses below. I upgraded mine to the new Pro XS version which came from the Sea Pro model as I had bolts/nuts loosening up that I’ve never had to check on an outboard before as well as excessive wear on the bracket and troubles controlling chinewalk. Since you bought the boat used and not sure how hard the previous owner ran it you might go over it, you can search my other threads for details if interested.

Midnight Rider wrote: The high temperature sensor has nothing to do with the water pressure gauge.  The temperature sensor is an on/off switch that sets off the horn/beeper when the temp reaches whatever the sensor is supposed to be set to…generally, that is around 180 degrees (at least it is on a Yamaha SHO).  If you have standard Mercury gauges (comes on the Sabre), it’s simply a fitting on the engine that is installed after removing a bolt that is on the water jacket. If you remove the cowling, you should be able to spot it easily, as it is nothing more than a brass nipple with tubing attached. The gauge is a simple mechanical analog gauge.  It sounds like a poppet valve is stuck, but I’m not sure your engine even has a poppet.  It does have a thermostat, which could be suspect.

It sounds like you might have blockage in the water passages somewhere.  It doesn’t take much, BELIEVE ME.  Upper maximum pressure on my SHO and my Sabre FTD is 25 psi, and will drop to as low as 11 psi when trimmed up all the way. I’ve not personally heard of an outboard that puts out 43 psi at any time.

My understanding is he got the high temp alarm from raising the motor and his pressure gauge apparently isn’t working properly as it got hot from lack of water. I would think an obstruction would cause it read low, regardless you can see in one of the videos I posted where the 30psi gauge is pegged while running WOT. I’ll admit it freaked me out the first time that happened as I thought I had lost all water psi then when I slowed down I realized it dropped from 30psi. The faster you go the more you cram water into the intakes and cause an increase in pressure, the closer the lower unit is to being parallel to the water’s surface the higher the psi reading will be.