f250 temp alarm

[mullet76]

I have a 2005 f250 that the temp alarm keeps going off while idling for a few minutes, gauge says motor is not hot. Only does it when idling. Replaced water pump but didn't help. Sending unit maybe?

[99yam40]

check pressure relief valve ,
may be stuck open dumping too much water at low RPM to keep the block filled up

[boscoe99]

If the pressure control valve is functioning correctly then the next step might be to view the exhaust cavity. Remove the lower unit. Tilt the motor to the full up position. Using either a borescope or your eyes and a strong flash light look up into the exhaust section. What do you see up there?

Early model F250's are prone to the exhaust section rotting out from corrosion. One of the first things seen is that the motor will over temp when at idle.

[mullet76]

If the pressure control valve is functioning correctly then the next step might be to view the exhaust cavity. Remove the lower unit. Tilt the motor to the full up position. Using either a borescope or your eyes and a strong flash light look up into the exhaust section. What do you see up there?

Early model F250's are prone to the exhaust section rotting out from corrosion. One of the first things seen is that the motor will over temp when at idle.

When I installed the new water pump i looked up in the exhaust cavity with a bright light best I could and everything looked good. Is there any way to check the pressure control valve?

[99yam40]

From what I have read the inspection of exhaust erosion needs to be done by someone that knows what to look for.
If I remember properly ,You look for edges of gasket sticking out from the metal sealing surfaces that have eroded away. Most say impossible to see the problem to untrained eyes.

PRV ,
just need to pull it out and inspect, but need to look to see if it is stuck open before removing it.
Corrosion develops under the grommet which causes it to expand and grab the valve and will not let it move properly
Be very careful you do not lose it inside the block when messing with grommet

[greasyshaft]

F250 uses a plastic/rubber PCV (one piece assembly) located at the top of the midsection, you will have to remove the two side fairings and then the single shroud at the top of the upper casing,
You then remove the stopper and wind out the PCV (big plastic nut) using a large crescent.

Part 8.
2006 and Later F250BTUR Yamaha Outboard UPPER CASING Diagram and Parts

Other wise get that exhaust checked out by a dealer, I don't know what happens in the states but Yamaha is quite good about it here in NZ. I have had to do a few lately.

[rodbolt17]

your describing a classic ex stack failure symptom.
especially if you get an audible with no visual indicate.

[mullet76]

I ran the engine in a tub yesterday afternoon for at least 30 to 40 minutes and could not get the alarm to sound. So when I got home today I ran it again and after 13 minutes the alarm sounded, temp gauge was normal. After the alarm sounded I shut it down and started it right back up, took a little over a minute and the alarm sounded again. Shut it down and started it back up and ran the rpms up to about 1500 and let it run there for 2-3 minutes then dropped it back down to an idle and it idled fine for 30 minutes, no alarm. Just can't figure it out, I would think if it was corrosion once the engine warmed up the alarm would sound off consistently?

[rodbolt17]

what make is the so called "temp gauge"?

[mullet76]

what make is the so called "temp gauge"?

Same one I see with all the yamaha analog gauges.

[rodbolt17]

ALL Yamaha audible alarms are the same tone.
you determine WHAT set the audible by the TACH visual.
gauges other than the TACH are irrelavent.

however your describing a classic stack failure.

[TownsendsFJR1300]

Just curious, what part # is the exhaust stack / failure part? (is it on that link?)

[rodbolt17]

two common areas are the plate between the oil pan and muffler and the gasket area by the adapter plate.
one leads to low speed overheats the other water in the oil.
its also why Yamaha developed a kit.

[boscoe99]

Read all about it. A widely known issue.

As Rodbolt noted Yamaha is offering two kits to fix motors that need to be repaired. One for 2002 - 2003 models and one for 2004 - 2005 models. Even some later models have been known to get the cancer.

https://www.google.com/search?q=yama...a&channel=fflb

[TownsendsFJR1300]

Read all about it. A widely known issue.

As Rodbolt noted Yamaha is offering two kits to fix motors that need to be repaired. One for 2002 - 2003 models and one for 2004 - 2005 models. Even some later models have been known to get the cancer.

https://www.google.com/search?q=yama...a&channel=fflb

I've known about the issue, from the forum here, just wasn't sure which part it was. Thanks for the links, interesting...