F250 Overheating Issue & Question

[Fowl Hooked]

Any thoughts on this one - out fishing today and on three separate occasions I got an overheat alarm on the port engine (2015 F250, 3.3L block), shut it off, restart and it was fine until the next time; after the third time I left it off for good and just trolled around on one until we picked up to go back in. It did it once last weekend, also while trolling, it had never happened before so I wrote that one off as a 'glitch'. No issues when running at speed. No visual indication of an overheat, temp on the gauge was dead center where it always is and mirrored the starboard engine - which had no alarms. Temp sensor appeared to be working as I watched the temp climb after restarting the engine, don't know that it's accurate but it is reading variations in temp. Good stream from the pisser, looked like it always did. Had the annual engine maintenance done as always during the off season and have run it for maybe 10-12 hours since then, some at speed but most while trolling, turning anywhere from 600-1000rpm. Engines are still under warranty but my Yamaha certified shop is an hour and a half away and I'd rather not have to pull the boat and haul it up there. If my local shop can put a computer on the engine is there anything they might learn from it? I've seen RPM readouts but don't know what all they can get from the computer. Other things I can check before resorting to pulling the boat? Thanks.

 

[SmokyMtnGrady]

I notice you are in Maryland and given the time of year, I think it's too early for dolphin up your way. I could be wrong. My first thought you trolled through some sargasso weed and got some clogged in your pickups . The other thought is you need either a new water pump or your t stat is not opening up at low speed? Yet a third possiblity is your sensor is acting up? I wish I was more help but these are typically the reasons for over heating .

 

[seasick]

Usually when you get an overheat alarm and shut the motor, if you restart it right away, you will still have the alarm. It takes a while for things to cool down.
Since you checked the temp gauge and telltale and they looked normal, it doesn't look like a real overheat to me. Could be a bad thermo switch (not temp sensor). Although I really don't like to suggest this approach, if your thermo switches are pressed into a rubber busing on the head(s) you could easily swap them between motors and see if the alarm moves to the other motor.
I need to look at a parts diagram to make sure you have thermo switches and if so how many.

 

[seasick]

It seems like there are two thermo switches on the F250 and I think they are the push in type. Just make sure you swap the thermo switch (part 61 on the Boats.net diagram, cylinder head)
Check the connectors first of course.

 

[Fowl Hooked]

I notice you are in Maryland and given the time of year, I think it's too early for dolphin up your way. I could be wrong. My first thought you trolled through some sargasso weed and got some clogged in your pickups . The other thought is you need either a new water pump or your t stat is not opening up at low speed? Yet a third possiblity is your sensor is acting up? I wish I was more help but these are typically the reasons for over heating .

In Maryland, yes but on the western shore of the Chesapeake Bay and trolling for stripers right now. That said, I could still have picked up something to clog the pickups. Would the pee stream be affected by that at all? Stream was solid in all operating conditions, in fact it was probably a little stronger than the starboard engine, but I honestly don't know the plumbing from pickup to pisser. I need to call the GW dealer where I get the engine servicing done and see if they inspected the water pump and thermostats this last time around. I'm leaning towards sensor but would have thought the temp reading on the gauge would have indicated an overheat but perhaps the two aren't coupled and it's just sending the alarm signal straight from the engine computer? Thanks for the input.

 

[Fowl Hooked]

It seems like there are two thermo switches on the F250 and I think they are the push in type. Just make sure you swap the thermo switch (part 61 on the Boats.net diagram, cylinder head)
Check the connectors first of course.

Thanks for the research. I'll have to look for that schematic. Does swapping / replacing seem like something that I (or a mechanic) could do with the boat still in the water?

 

[SmokyMtnGrady]

I was going to suggest the above. The pee stream is an indicator of the water pump working. It's not necessarily an indicator of the thermostat being open or closed.

 

[Summertop511]

Not sure but is there a poppet style system on the 3.3L’s?

 

[Sparkdog118]

Sometimes a stronger p stream means there is a blockage in the power head like a pressure valve sticking or a slightly stuck thermostat.

 

[HMBJack]

If the boat is in the water, buy or borrow an infa-red heat gun.
Then run the boat and get the engines Hot (note: idling in the slip does nothing - you gotta run em).
Turn off the engines and pull the hoods.
With the Heat Gun, inspect the temperature at the Thermostat Housings.
If one is much higher than the other, it could be stuck or clogged.
If all T-Stats show the same temp, then perhaps they aren't an issue.

As to the thermostats: There is one on each side of the power head, up high below the flywheel.
(I didn't know the 3.3L went into 2015. Last year of them maybe?)
Anyway, to remove the Thermostat, grab your 10mm socket and have at it.
Try not to drop a bolt.

Once removed, place the Thermostats in very hot water to test.
I'll bet when you do this, you'll see the issue.

 

[seasick]

Again I think that when head and t-stat overheats, after you shut down and immediately restart, the alarm will still sound again. The thermo switch can not reset that fast.

Yes the swapping is possible in the water as there should not be any bolts to deal with. I believe that thermo switch just pulls out of a rubber boot. With the motors tilted up, you have less of a chance of dropping something in the brink.

The thermo switches can be tested using an ohmmeter, a thermometer, a pot of water and a stove. They basically switch on or off at two set temps, one on the way up(getting hotter) and a different one on the way down(cooling off). I suppose one of yours could be intermittent but I haven't seen that. A loose connection could also be the cause
Remember that you would swap both sensors between motors. If the alarm changes engines you know one of the two is bad. To find that out, you now have to swap one only between motors. If the alarm changes motors, the last on you swapped on the motor with the alarm is bad. If the alarm occurs but on the same side that had the alarm after both were swapped, then the one you didn't swap is bad.Did I confuse you? I may have confused myself

 

[Sparkdog118]

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This is a Yamaha diagnostic program that can be loaded into your laptop and is simple to use. It is a wealth of information for both of your motors and will answer lots of your questions. It is a must have for someone with twin 4 strokes to keep tabs on your engine’s health.

 

[Sparkdog118]

I have plugged in to 2015 Yamaha outboards and it works just fine.

 

[seasick]

it is handy but if the sensor is bad and triggering an overheat alarm, that's what the log will show, an overheat condition.

 

[g0tagrip]

Okay I will throw in my two pennies worth......my guess is you have a bad blade on the impeller. I say that because last year I had a similar problem with my port engine at low power settings and after checking thermostats, etc., dropped the lower unit to find one of the blades on the impeller was bent badly. Replaced the impeller and no issues since.

 

[Fowl Hooked]

Appreciate all the input. As the boat is in the water I think I'll try starting at all the connection points I can reach and ensure they're solid. Sounds like swapping the sensors between motors to isolate if that's the fault may be the next way to go followed by the thermostats, though I have been looking for a reason to buy an IR heat gun so I may try the run and measure approach first. I'd like to believe that the impellers were inspected when the engines were in for annual maintenance but I'll need to call the shop to confirm. Would have also thought the t-stats would have been inspected but don't know for sure. Thanks again, will update whenever I get this figured out. Guess it's a good thing that I'm fishing from a buddy's boat this Friday.

 

[seasick]

Appreciate all the input. As the boat is in the water I think I'll try starting at all the connection points I can reach and ensure they're solid. Sounds like swapping the sensors between motors to isolate if that's the fault may be the next way to go followed by the thermostats, though I have been looking for a reason to buy an IR heat gun so I may try the run and measure approach first. I'd like to believe that the impellers were inspected when the engines were in for annual maintenance but I'll need to call the shop to confirm. Would have also thought the t-stats would have been inspected but don't know for sure. Thanks again, will update whenever I get this figured out. Guess it's a good thing that I'm fishing from a buddy's boat this Friday.

Buy the IR thermo. It is super handy for a lot of things both for the boat and in the house. A lesser expensive model works fine, just remember that it's strength is being able to measure relative temps and not actual temps. Different types of surfaces reflect differently. More expensive model allow you to select a factor for those materials but in general it isn't needed. One other perk is that you can measure the forehead temps of your passengers, just add 5 degrees or so to the reading