2022 F250 - 1 hour old (last November). Went to launch, now overheating. What now?

[Wharfcreek]

Last November I took delivery of a brand new 2022 boat including a new 250HP Yamaha outboard. At delivery everything went fine, took a test run up and down the river, was out maybe 45 minutes with no problems. Rolled the boat home here in the Baltimore, Maryland area, flushed the motor and sprayed it with fogging oil, drained and did all other required 'winterizing' to the water pumps throughout the boat, and covered it for the winter. As of yesterday, I uncovered the boat and 'trickle' charged the batteries, which were actually still fine. I have 2 Midtronics battery testers...... both bats in good shape! Put muffs and hose on the motor, started the water flow, and hit the key! Engine fired immediately!! GREAT!!! Down hill from there. After a few minutes I noticed that the upper exhaust vent at the back of the motor had no water coming out of it. At the time I guess I was concerned about this and totally neglected to see if the 'pee' stream was there. After less then 5 minutes I heard a warning sound from the console. I checked the gauge and it appeared the engine was overheating. I shut it down and shut off the water at the hose bib. So, to confirm, I had good water flow from my hose as I had water flowing out the prop hub and around the lower unit. Water coming out of the prop was warm, but not hot, and certainly not 'over-heat' hot! I've had about 15 boats in the past 20 years, including a good many with V-8 motors and outdrives. All these have been run on my hose and water supply, so I have some level of confidence that 'water pressure' or 'water volume' is not the problem...... but I'm open to suggesting that it is. I did NOT try to rev the engine during any of this. But, I did inspect the pee hole and saw no obstructions. So...... what now? Engine has less than one hour. Spring start-up was WITH water ON and muffs properly located PRIOR to starting engine. So, water should have been forced into water pump by virtue of the hose pressure. The point here is that I don't think one could accuse me of having burned up the pump by running it dry. Beyond that, I'm appealing to the experts here. If poppet valve was stuck closed could that cause an overheat at idle? Or, if T-stats were stuck closed, could that do it? Bottom line: HELP!!! Thanks, Tom D

[Keithbaja]

Hi, Its very late in the evening for me. Having insomnia. ARRRG ! Make sure your using a dual feed muff and look around the lwr front gear case for other water intake feeds. They are sometimes hard to find/notice.

[fairdeal]

As of yesterday, I uncovered the boat...Put muffs and hose on the motor, started the water flow, and hit the key! Engine fired immediately!!

Spring start-up was WITH water ON and muffs properly located PRIOR to starting engine.

I'm not following -
was yesterday the "spring start-up" ?
or was there a prior occasion when you ran it?


In any case - a few things
1. AFAIK a "2022 F250" can only be the 4.2L - and that doesn't have a "poppet valve"
2. At idle, you would NOT expect water to exit the "upper exhaust vent at the back of the motor"

As Keith observes, there are (unless you have the VF250 SHO model)
FOUR water pickup screens on the lower unit;
you can get muffs on the upper pair,
but you have to tape over the bottom screens

[99yam40]

I'm not following -
was yesterday the "spring start-up" ?
or was there a prior occasion when you ran it?


In any case - a few things
1. AFAIK a "2022 F250" can only be the 4.2L - and that doesn't have a "poppet valve"
2. At idle, you would NOT expect water to exit the "upper exhaust vent at the back of the motor"

As Keith observes, there are (unless you have the VF250 SHO model)
FOUR water pickup screens on the lower unit;
you can get muffs on the upper pair,
but you have to tape over the bottom screens

Sounds like if he does not block off those bottom screens air will be sucked into the pump, is this correct?

[boscoe99]

Put the boat in the water. I suspect that the motor will be just fine.

[DennisG01]

One thing isn't make sense with the "extra intakes" notion, though... Wharf mentioned that he flushed it in the Fall with no problems. Wharf... did you flush it for at least as long as you did this time? Did you do anything different?

BUT... if you do have extra intakes... as mentioned you need to tape over them or put it in a bucket (or the water).

[Wharfcreek]

OK, happily I can report that all is well! I decided to just go ahead and haul it to the marina and float it and run the motor. After about 5 minutes the temp gauge never left the 2nd indicator. Went ahead and launched it and ran it out to the Chesapeake Bay, then ran it home. I live on a creek just off the Bay outside the Potapsco River and Baltimore Harbor (Bodkin Creek for those interested). Anyway, no overheat and everything worked as it should. I suspect my muffs were insufficient, as well as my error in not blocking off the other set of intake screens. Live and learn! So, looks like I can chalk this off to 'pilot error' and move on. Thanks to all above for the good info and quick responses. I'll know better next time! Tom

[zenoahphobic]

Happy that there was nothing wrong with your engine, extreme bad luck if there was with less than an hour on it!

[99yam40]

big question is, are you following the break in procedure?

most people break the motor in when they get it before putting it away

[Wharfcreek]

I didn't have much choice but to simply take the test drive, take delivery, then take it home. I probably don't have to mention how difficult it's been to get new boats, let alone new outboards. Anyway, in my run today I was very careful to observe the recommended break-in process: varied RPM, no hard hole shots, and strict attention to gages. I've got another 8.5 hours to and then the 10 hour service. I'm told after the 10 hour service I should still take it easy on it for another 10 hours or so. But, I'd welcome any comments on this part of the deal. I did note what felt like a 1-cyl 'miss' initially, but after 10 minutes or so at about 3500 RPM and then back to just idling around it seemed to clear up.

[Wharfcreek]

I should add to the above that the 'purchase' of this boat was completed in late November..... which is when I took the test drive and the delivery. DennisG, that is when I brought it home and flushed it. At that time I had no warning alarms go off, but perhaps I didn't run it long enough. In late November the Elk River where I test drove the boat is mostly Fresh Water, so the flush factor was really almost unnecessary. But, boat came home and was covered for winter within the week. I just did the final winterizing and covered it. Honestly, it seemed almost tragic NOT to bring it home and at least run it a bit, but with winter descending quickly it just seemed the 'rational' thing to do. Fairdeal, Yes, (day before) yesterday (Tuesday) was the 'uncover' and 'start-up' day. Thankfully, today's launch went well. I mentioned above the quick run after the launch earlier this morning, but took another ride later this evening and boat ran equally well with perfectly stabile temp in the 'normal' range. I again felt the same vibration, mostly on throttling up to bring the boat up on plane. Once on plane and running again at about 3500 everything smoothed out. Ran it at varied RPMs for another 10 minutes or so out on the Chesapeake, then came back into my creek and idled around for another 20 minutes or so. At that point it was perfectly smooth and I felt no indication of any kinds of vibrations. Guess I'm just super-sensitive to this kind of thing. I spent over 34 years with an auto manufacturer in a technical capacity, was a past ASE Certified Master Tech, and have been around boats since I was 10. Like my motorcycles, if I've had one boat, I've had 50, ranging from an old 1947 Chris Craft 17' Deluxe Runabout, to a 40' Owens. I've had fishing boats, weekenders, race boats, cigar boats, walkarounds, bowriders, center consoles...... you name it! I can now say that I'm DONE with I/Os or inboards. Outboard motors have come SO far in the past decade!! I hope I'm as delighted with this new Yamaha as I have been with my now nearly 20 year old EFI 60HP 4-stroke Merc! I've run that motor almost every day out in the Chesapeake for the past 15 years, since I bought it from it's original owner. I think it had about 10 hours on it when I bought. Probably got 10,000 on it now!!.....lol. Anyway, thanks again for the help and info. Hopefully I'll not have any further issues to bring up here for help. Enjoy the boating season in 2022 and be safe! Tom D.

[99yam40]

well sometimes you do what is necessary, Good to hear you are taking care of things
no idea if break in while in cold water would be any different that warm areas
enjoy the new boat & motor

[Keithbaja]

Yep, those mercs are bullet proof. Got two (2) 75's (2004) hanging on my 19' catermaran and wouldn't change them for anything. Two strokers !!

[oldmako69]

Just remember to put drano on your plugs each fall and you'll be fine!


One thing I learned about these larger engines is that the are intolerant of any loss of coolant flow. If you didn't have a super tight seal on the "muffs" and or you have a four intake hole LU, your chances of keeping it cool on a hose are low.

Consider that when the LU is in the water under normal ops all of the intakes are under significant pressure from their relative depth (PSI increase) and that the water pump is being JAMMED full of a lot more water faster than it can pump it out. When flushing with your hose? Not even close is my guess.

[zenoahphobic]

Just remember to put drano on your plugs each fall and you'll be fine!


One thing I learned about these larger engines is that the are intolerant of any loss of coolant flow. If you didn't have a super tight seal on the "muffs" and or you have a four intake hole LU, your chances of keeping it cool on a hose are low.

Consider that when the LU is in the water under normal ops all of the intakes are under significant pressure from their relative depth (PSI increase) and that the water pump is being JAMMED full of a lot more water faster than it can pump it out. When flushing with your hose? Not even close is my guess.

It seems Yamaha doesn’t want you to run and flush their engines.
After decades still no sign of adequate systems.
Even a pretty poor house water supply would supply enough “heat exchange” water to take away the heat produced at idle - a simple maths problem, so why are we not offered a proper hose connection into the engines cooling passages that actually have very little volume?