Potential Water Flow Problem F250 (08)

[bjd76]

Had my impellors changed last year but noticed the starboard engine tattle tale flow is about half that of the port engine now. No warning alarm sounds and stream is weak but not intermittent! I go out 120 miles so hearing an alarm at that point would be very disconcerting.

Further understand that (tattle tale) water flow can be influenced by impellor, thermostat, and an exhaust poppet valve but that the F250 does not have the poppet valve.

Given that engines have 900 hours (flushed religously BTW) do you think it likely to be the thermostat of impellor. And if not the impellor, should I check the thermstat visuall for impairment (can you do that?) or just buy 2 repacement thermostats for the starboard engine?

Everyone's thoughts? Thx.

[99yam40]

Stats should not effect tell tail, but they are a normal maintenance item.
Pull ,inspect, and test for proper operation or replace like Yamaha recommends.

Weak tell tail could be water pump or plugging of tell tail passage, you can try blowing some compressed air back through to see if that will help.
But I would have a look at water pump to see if it has problems before heading out that far again

[rodbolt17]

the F250, like ALL other F v6 motors DOES have a pressure control valve.
like all others this ALSO needs maint.

[bjd76]

Pressure Control Valve

Guy at the parts counter did not see an exhaust poppet valve in the F250 diagram. Assume that is the pressuvre control valve you are referring to. And, if so, could it affect the tell tale?

If the thermostat is stuck half way open wouldn't that affect the water flow out the tell tale?

[99yam40]

Guy at the parts counter did not see an exhaust poppet valve in the F250 diagram. Assume that is the pressuvre control valve you are referring to. And, if so, could it affect the tell tale?

If the thermostat is stuck half way open wouldn't that affect the water flow out the tell tale?

If prv is stuck open and dumping water into the exhaust before it runs through motor then it will not make it to the motor or the tell tail.
Stat stuck open still is running through motor and tell tail

[bjd76]

OK water is still coming out - just at a reduced rate. If stat is only open half way wouldn't that affect flow rate? I have snaked 200lb mono thru tell tale and sprayed WD40 up it as well. Which would you check first, stat, pvc, or impeller?

[rodbolt17]

all of the above plus make sure the regulator passages are clear.
the regulator is water cooled,by the tell tale water, shut that off or reduce it and regulators can catch on fire.
have your parts guy look at the upper casing for the prv.

[bjd76]

Talked to Yamah today and learned that the charging system is water cooled by same tattle tale system (as noted above). Girst step, gonna take brass elbow off block and inject water/compressed air in each direction to make sure there is no blockage. See what happens from there... Thx for all the comments.