Finally stored a Code 46! (whiskey tango foxtrot)

[fairdeal]

So I did another round of temp indication testing this morning.

I had the YDS connected, but the Garmin units off - so I would not be distracted by "Command Link" alarms and could focus on the plain Multifunction Tach.

I began by "shorting" one set of harness thermoswitch leads.

First time running the engine today, so engine temp was 80F when I started it.

After idling for >6 minutes with no alarm; engine temp was up to 137F.

Knowing that the MTG mentions different behavior above 2000 rpms, I pushed the throttle up to 2,164 rpms.

Continued running 3 more minutes - still no audible, no flashing tach symbol.

I was checking engine temp on YDS - it had gotten up to 148F -

and then I noticed YDS was showing "Irregular" on the Diagnosis screen for Code 46!

And when I checked "Diagnosis Record" the code was stored!

But there had been no audible!

uploading pictures


Now - here's the crazy part:

a few minutes later, I tried it again.

Just the thermoswitch leads shorted.
The engine temp was already 144 when I started.

After idling ~ 60 seconds - audible alarm! flashing tach symbol!

But this time - YDS showed "Normal" for all parameters - and no code stored.

So why the difference?

Temperature?

below a certain engine temperature, the ECU interprets a closed (ON) thermoswitch as "Irregular", stores a Code 46, and does not activate the tach & audible alarm?

above a certain temperature, the ECU accepts a closed thermoswitch as "Normal" - doesn't store a code - but activates the tach & audible?

or was the difference the >2000 vs 700 rpms?

too complicated....

[99yam40]

so, on the second test did you ever get over 2000 RPMs during that key on cycle when it set the buzzer and icon??

maybe this should have continued on the other thread

[fairdeal]

so, on the second test did you ever get over 2000 RPMs during that key on cycle when it set the buzzer and icon??

no - just idle.

Because, the first time, I hadn't seen exactly when the YDS changed the "Diagnosis Result" from "Normal" to "Irregular"

I planned to watch that carefully the second time, while repeating the timeframe.

Then very quickly the audible sounded.

[rodbolt17]

there ya go.
that is what I have observed.
why I dunno.

like I said that was the first indicate of a failing ex stack.
random audible with or without a visual,typically without, and normal thermosensor output.
scroll down and you would see the thermoswitch on.

kinda like a pair of F225 motors I did a few years ago.

complaint was the stbd engine would occasionally stall while docking.

cust took me out for a sea trial.

idle well, turned up about 4800.

stalled when docking.

BOTH TPS sensors were stuck solid.

should have been high idle and top speed cannot be reached.

so I have found over the years that not ALL ECU's do what Yamaha training manuals state.

[rodbolt17]

your simply not getting it.
the thermosensor and the 2 thermoswitchs are entirely separate circuits.

a code 15 simply means the ECU does not like the feed back voltage.


to get the correct visual indicates that an engine overtemp has occurred requires 'typically" one of the two switch's closed and the thermosensor voltage above a set threshold.
remember the sensor is a 5v circuit.
the sensor is a negative temp coefficient.
as temp increases resistance acrossed the sensor decreases.
this allows more current and drops less voltage.

Yamaha does not publish ECU mapping data.

the switch is simply open or closed.
the ECU sees this ground path as a low.
low lights the light in a typical digital circuit.

use the engine monitor function instead of the diagnostic screen

that way you can watch both the sensor AND the switch's.

it is possible to trigger a thermoswitch yet the thermosensor stay in range.
227*F is way hotter than what is normal.
typically it is less than 190*F when running hard.

that is why to properly test the system requires the sensor to be bypassed with a 2K resistor AND the pink and black leads for the switch to be shorted.

[fairdeal]

Hi Ya' all!

But, fairdeal has put a new stack on his 2005 F225 at 1000 hours, and his F225 has just shy of 1600 hours now. Has his stack failed again?


Any chance (Rodbolt/Boscoe/99Yam40) it could be thermostats sticking on my engines and not the stacks?
The YDS says I gots 600 hours on each engine, and T-stats have not been changes + I have been laid up for 9 months recently replacing things on these engines. IOW.. No hard running every week!

I'm going to take my trusty mokanic Floyd out for a test run to duplicate issues next week. He can get the alarm to stay off IMO - I'm just saying that now to irk you.

Might as well pay him to change the T-stats that day too - then test them one time myself for alarms (than order three stacks with oil pump kits I suppose).

My exhaust stack is fine. What I've been posting about is just "exploration" - under "test conditions".

If you still have the original thermostats in your 2005s - I can easily imagine you could have reduced cooling flow.

In fact I won't be surprised to hear that Floyd needed a crowbar to remove them....

[rodbolt17]

11 years with no maint?
good luck with them thar 6mm bolts.
reduced water flow can and will toggle the switch's.
can also be why the block,while not overheated, is showing a higher temp than normal.

[99yam40]

Hi Ya' all!

But, fairdeal has put a new stack on his 2005 F225 at 1000 hours, and his F225 has just shy of 1600 hours now. Has his stack failed again?


My overheat switch (15) is never triggered as irregular on the YDS on any of my 3 F225s (2005s same as fairdeals). It actually reads OFF on all 3 on the YDS when checked.


Any chance (Rodbolt/Boscoe/99Yam40) it could be thermostats sticking on my engines and not the stacks?

If you pay attention to fairdeal's posts here and on your thread he is testing things to see why and when the over heat alarm will come in.
trying to figure out why you are getting an alarm but no icon on tach.

Have you had YDS hooked up and monitoring the switches to see if one or more is closed(on ) when the buzzed sounds?
I believe You told us on your thread that you cannot see the switches on your YDS for some reason, but now are saying it shows them as open(off)

IMHO if stats stick you would see the block along with the heads overheat, so both switches and sensors would see overheat at the same time which you are not seeing.

with that said reduced, cooling flow is happening if temps are higher than normal.
Have you even looked at stats and PRV in all of this lime of running those motors?
probably lots of build up in the passages too

[rodbolt17]

I don't care how good the tech is.
6mm bolts stick.
snap it off and you get to remove stuff for access with a drill.
if you drill carefully you can chase the hole with a tap.
sometimes you get to heli coil them.
all this takes time and skill with a drill.

[boscoe99]

My exhaust stack is fine. What I've been posting about is just "exploration" - under "test conditions".

If you still have the original thermostats in your 2005s - I can easily imagine you could have reduced cooling flow.

In fact I won't be surprised to hear that Floyd needed a crowbar to remove them....

He might have even better flow. Perhaps the thermostats by now have all corroded away and their remains are at the bottom of the briney blue. He might remove the cover to find nothing there.

[pstephens46]

I don't care how good the tech is.
6mm bolts stick.
snap it off and you get to remove stuff for access with a drill.
if you drill carefully you can chase the hole with a tap.
sometimes you get to heli coil them.
all this takes time and skill with a drill.

What's that? 18 6mm bolts? Remains could be on the bottom of oceans or plugging some other passage.

[scofflaw]

I don't care how good the tech is.
6mm bolts stick.
snap it off and you get to remove stuff for access with a drill.
if you drill carefully you can chase the hole with a tap.
sometimes you get to heli coil them.
all this takes time and skill with a drill.

What's your technique with the torching to minimize breakage ?

[rodbolt17]

cannot be any hotter than Rio Chico VE or El Manteco VE.
worked many a day in it.
we had the hottest summer on record of late. worked every day in it.
I have worked at marinas with dry stacks holding 350+ boats since 99.
I bet I have replaced as many or more.
probably drilled tapped/helicoiled more than most techs.
depending on access sometimes oxy/acetylyne helps.
sometimes you get lucky.
sometimes you simply snap the fattener and go on.

PS
PB blaster is a total waste of time on AL oxide.
you simply cannot get it were it needs to be.
it does not eat at AL oxide like it does Fe oxide.

[rodbolt17]

if I try anything it is typically Fluid Film.
simply because it does not flash when hit with the oxy/acetylyne.
that AL oxide can weld a fastener in the hole.
can be some mean stuff.

[fairdeal]

Rodbolt17/fairdeal

UPDATE: NO MORE ALARMS after replacing 6 thermostats.
REPLACED all 6 t-stats on my three 2005 F225s this morning.

The old 11 year old t-Stats were corroded badly. He had to pry a few out.

Glad to hear that mystery is solved.

I would also bet you've got corrosion where those thermostats fit into the block.

This is what mine looked like after I pried the thermostat out two years ago - it had presumably sat untouched for almost ten years: