Yamaha 250 2 stoke temp guage

[oldcobia]

I have been reading that given the choice between a temp and water pressure gauge the best choice would be the pressure gauge. Why is this the best choice? On digital gauges does the alarm for high temp go off when the temp is too high or when it is getting to the point it should be checked?

[almetelo]

Not answering to your question just let me post my opinion...

On my F100 I have 5 gauges



2 of them are a temperature gauge and a water pressure gauge.
This motor block just allow 1 gauge or an exit/entry for 1 sensor but I ordered a fitting on the machine shop so I could have both as I wanted both or none...

After 2 seasons I donīt think these gauges are very usefull for my appliance (IMO)

On a future boat/motor I donīt want/need these 2 gauges.

Which one is the best choise IDK
For me none of them but... If you have so money to spend and you like to see gauges on you dashboard go ahead as for sure you'll have more beneficts than setbacks.

Good luck on your choise.

[rodbolt17]

trust the alarms, test them occasionally.

only time water pressure is really nessasary is on a jack plate.

[fairdeal]

...On digital gauges does the alarm for high temp go off when the temp is too high or when it is getting to the point it should be checked?

Interesting distinction.

I am reminded of the scene in Ghostbusters where "Venkman" (Bill Murray) says ""I make it a rule never to get involved with possessed people."
but quickly clarifies "Actually, it's more of a guideline than a rule..."

On the 4 strokes that I am familiar with, the alarm sounds / lamp flashes coincident with the ECM taking control, to drop the rpms.

Perhaps that means both: the temp is too high, AND it should be checked.

[RayBersch]

What is your real goal?

I don't know where you have been reading but below is a quote from the FAQ's on the Yamaha outboard web site. It pretty much points out the uselessness of a water pressure gauge except at WOT, and most of us that have transition from another brand will be quite surprised at only 11 psi at WOT. I found this out after spending a bundle on a water pressure sender for my F150 and being shocked by the readings.

So, what is your goal? Usually we really want to know water temperature and we "know" that low water pressure could lead to overheating. But water pressure is just a proxy for what we really want to know and as you can see, pressure will be low except at WOT due to design of the engine. I now monitor water temperature on a Lawrence multifunction device (HDS 7 Touch) via a link to the engine, but frankly, I depend upon the built in alarm.

What is the minimum water pressure required for my Yamaha outboard(s)?
All Yamaha outboards have a minimum water pressure of eleven (11) psi at Wide Open Throttle (WOT). There are no announced water pressure specs for low or mid-range operation at this time. This is due to our high volume low pressure cooling system design. In fact, you may see zero pressure at idle, as most water pressure sensors start working at 3-psi.


Hopes this makes the issue clear to you.

Ray

[scofflaw]

Hi water pressure readings are a red flag as well, indicating a restriction

[oldcobia]

I would like to have other means indicating potential temp problems that may come up.

[scofflaw]

I would like to have other means indicating potential temp problems that may come up.

Agree, with temp being the main concern water flow is irrelevant.
Hot horns are equivalent to idiot lights on 60's vehicles. who knows when it goes off and at what temp? Too late and damage is done.

I like a temp gauge and know where the needle is when it's running at a normal temp.

[almetelo]

water flow is irrelevant..

If I'm understanding well your comment I donīt agree with you...

IMO water flow is very importante!!! Have a gauge to have a look on that is not...

Last week changed impeller on my F100 as motor was not peeing with the same power as before (not because I have a water pressure gauge), so for me was the reason to change impeller and never had any overheating problems.
Just want to keep a good water flow (best as possible)so water get to all passages.

In fact some impeller blades were a little horn

[RayBersch]

almetelo, you used the telltale stream as an indication that you needed to change the impeller (instead of regular maintenance) so you did not need a pressure gauge. What you noticed is that the stream was weaker than normal so you took action. With the newer motors if you are moving along at 2000 rpm through a no-wake zone and saw 4 psi would that alarm you? According to Yamaha, it shouldn't. But if you had a temp gauge and noticed the temperature was 30 degrees above normal with that same 4 psi (and telltale stream), you would probably stop and check for water blockage.

That's the point. You have a telltale (of course its important), you have an alarm. If you had a pressure gauge you would have spent a lot of money for little value.

[99yam40]

Pressure gauge could give you a heads up if it would read low and accurate enough to see what your motor does when pumping good compared to when it is not, but if most do not it is anyone's guess if it would be worth putting one on the motor.

and would you be looking at it often enough to make it worth installing it

A temp gauge reading water temp or even the head temp would also work well if you looked at it before the alarm went off telling you to look

[fairdeal]

Pressure gauge could give you a heads up if it would read low and accurate enough to see what your motor does when pumping good compared to when it is not, but if most do not it is anyone's guess if it would be worth putting one on the motor.

and would you be looking at it often enough to make it worth installing it

A temp gauge reading water temp or even the head temp would also work well if you looked at it before the alarm went off telling you to look

Good questions.

I have an F90 (actually, a "black Yamaha") that is prone to having the water intake blocked by seaweed.
I also have a mechanical water pressure gauge right on the console next to the tach.
Whenever the horn suddenly sounds & rpms drop due to overheat,

I immediately look down and can see that pressure gauge reading zero.

[boscoe99]

I used my water pressure gauge to monitor the condition of the water pump. With a new pump I would get X pressure at my normal cruise RPM. After a number of hours of use the pressure would start to fall off. Once the pressure reduced to a point where I was not comfortable I changed the impeller.

With the new impeller the pressure would go back up to its normal value.

[rodbolt17]

hahahahaaha


I immediatly look DOWN WHEN the HORN SOUNDS.

if ya didna hava horn when woooda ya loked down ?


that's why for the most part a temp guage and a water pressure guaage are teats on a boar hog.

horn sounds, ya got an issue. look at the tach.

neeed moe poiwer scotty.