cooling water pressure - F225TXRD

[fairdeal]

so I want to "see" the cooling water pressure (we don't need to get into why)

rather than remove a plug
(tried and stopped, as removal torque approached scary level for aluminum threads)

I Tee'd into the hose running to the fuel cooler from the back bottom of the block. Its easy to access as it passes the port side

But I'm seeing low single numbers - not even 3 psi at a fast idle (~1400)



barely got to 5 psi pushing the boat at 4000 rpms!

I assumed that would be maximal pressure as the water first enters the engine - am I wrong?

or do I have wimpy water pump pressure? bad PCV?

engine temperature is fine, never gets above ~195

[panasonic]

Are you running on the muffs, in a bucket or actually in the water underway?

I am only guessing, but I wouldn't think it would be much more then what you are seeing. Flow rate through the block would be more important for cooling then pressure, would it not?

Underway there would probably be some more pressure as the water is being forced tthrough the intake ports.

[99yam40]

I am fairly sure he was not running at 4K on muffs, at least I hope not.

I would question where you tied in not being a good spot to see the true pressure.
Too much restriction and then open to the outlet so pressure can not build up

[fairdeal]

thats 4000 rpms boat in water, moving at >25 mph (I'm not a "it revs fine in neutral" guy)

on the 3.3 F225, the water for fuel cooler/regulator rectifier/telltale comes off the base of the block

at the same point where the entire output of the water pump (less whatever the PCV relieves)
is delivered to the engine

I thought that tit to be seeing max pressure...

[pstephens46]

I read somewhere in Yam documentation that these systems deliver volume not necessarily pressure. As compared to some Mercs I have seen that would spray water 15 ft. Would be interesting to know gpm moving up the water tube.

[fairdeal]

I read somewhere in Yam documentation that these systems deliver volume not necessarily pressure.

I never measured the presure before, so no baseline;
I'm looking for a point of comparison

just checked my records,
the impeller is coming up on two years old with about 500 hours on it

saw it recently, and it looked fine - but maybe its lost some oomph...

[99yam40]

thats 4000 rpms boat in water, moving at >25 mph (I'm not a "it revs fine in neutral" guy)

on the 3.3 F225, the water for fuel cooler/regulator rectifier/telltale comes off the base of the block at the same point where the entire output of the water pump (less whatever the PCV relieves)
is delivered to the engine

I thought that tit to be seeing max pressure...

my thoughts are that small nipple and hose restricks water volume and dumps back out so pressure cannot build up.
see what it reads if you pinch off the outlet.

not for long, just to see if the pressure jumps up.

are you sure that is the inlet and not an outlet?

[boscoe99]

I can tell you that those plugs in a brand new motor are tight. Took me using a long ass breaker bar to get both of mine loose.

Anyway, what they do at the factory is to get a pressure gauge from say the Tokyo Home Depot. Get the necessary adapter fittings so that gauge can be plumbed to the garden hose flush inlet. Measure water pressure there.

Do it with a new water pump kit so as to get a baseline reading for your particular motor.

[fairdeal]

certainly when I get a round tuit and replace the impeller, I'll see what that does

I would go for removing the plug - if the pressure there were different

Boscoe, seems I recall you saying that you used a wp gauge to "decide when to replace" the impeller

what kind of values were you seeing?

[boscoe99]

certainly when I get a round tuit and replace the impeller, I'll see what that does

I would go for removing the plug - if the pressure there were different

Boscoe, seems I recall you saying that you used a wp gauge to "decide when to replace" the impeller

what kind of values were you seeing?

In my Mercury EFI the values were relatively high at lower/mid RPM's. I forget exactly what they were but at some RPM the pressure was pretty constant. For several years. Then one day the pressure started dropping at the baseline RPM. I watched it drop for a while and then one day the over temperature alarm sounded. I replaced the impeller. Pressure came back to what it had always been.

The Mercury was interesting in that the poppet valve opened to allow more water to flow through the block. I could see the poppet valve open on the gauge in the form of a pressure drop. The Mercury ran much hotter at low RPM's than it did at high RPM's.

In my Yam F200 the pressures were much lower. Nil at idle RPM and maybe 16/17 psi at 4000 RPM or so. I sold the Yam with only about 50 hours time on it. Never replaced the impeller.

[boscoe99]

Yam defect resulting in low water pressure.

[fairdeal]

Yam defect resulting in low water pressure.

ugh!
is that a 2-stroke? what part of the engine is that?

[boscoe99]

ugh!
is that a 2-stroke? what part of the engine is that?

Looks to be an SHO or Offshore oil cooler. Oil/water heat exchanger if you will.

[fairdeal]

well - looks like I made the wrong choice of hose to tap into.

Took Boscoe's suggestion and put a gauge to the "on board flush attachment"



the other end of which, on the F225, is the top of the "exhaust cover" between the heads:



Very different results.

(also, the engine is "cold" this morning - yesterday's data surely had at least some degree of open thermostats)

[fairdeal]

The data yesterday showed good correlation between the "Command Link" pressure sensor and the bourdon tube gauge.

Here is side by side
the electronic measurement of the fuel cooler/reg rec/pisser supply pressure
the mechanical measurement of the "flush port" pressure

at idle

[/url]

fast idle

[/url]

2200 rpms



So it appears that there is some sort of orifice - restrictor -
reducing the pressure allowed to go to the fuel cooler/reg rec/pisser

At a minimum, I'll be moving the electronic sensor to the "flush hose"

I will have to mull over whether I dare back out one of those blind plugs
which Yamaha apparently installed using The Loctite From Hell