2004 BF225 Overheating!

Hi All, I've exhausted myself with this issue & am hoping that one or more of you will take a crack at it - I've changed my impeller & flushed the motor 7 ways from Sunday with descaling solution for 30 hours - water flows well in all directions, pee tube included, when I flush with a hose but when I use ear muffs or run it in a tub it still over heats and that is with & without the thermostats in - sounds like a pump problem to me but I've been in there 3 times & all seems to be in order - any ideas? - thank you in advance!

So no flow (peeing)when running in the tub? But you have flow when you put a hose on the flush port?

You've probably already tried, but you may try taking the lower off, and flushing with a hose up the water tube to make sure you have no obstructions from the pump through the engine.

If you've got flow from there, it's got to be a pump issue, so I would replace the pump housing, liner, and all if you've only replaced the impeller. And make sure the water tube is properly lining up on the pump when you reinstall.

Agree with Wildebeest. To expand, the liner that the impeller seals to can wear and get out of round, thus degrading the amount of water pressure that can be generated.

BTW - the BF 200/BF 225 will normally overheat on muffs, unless you have exceptional water pressure on your hook-up hose.

The water tube is the only orifice I haven't flushed yet, but that's a great idea - and no, when I changed out the impeller I didn't replace any of the other stuff, so that's on the list...I have very good water pressure - it pushes water right up thru the motor & out the pee hole, which makes me think that the water tube cant be obstructed, but Im gonna flush it anyway...thanks for the thoughtful responses guys! If I have any notable revelations, I'll be sure to share them.

Before you tear everything apart, try running the motor in the water, as Chawk said, there are often overheats related to insufficient water supply.You also say you have good water prsssure, if so the pump must be okay. These pumps push way more than sufficient water even when worn.......

Are you certain the motor is actually overheating? Have you checked the manifold temps with an infrared thermometer? My 03 225 was recently "overheating" and it turned out to be a faulty overheat sender on the starboard side that kept tripping the alarm. I changed the sender and the problem went away. If manifold temps are normal, around 120F near the top you can disconnect the sensors one at a time to determine which one is causing the alarm.

iang - yeah, I've run the motor in a tub of water - it acts like the pump is moving no water - no pee stream...when I mentioned "good water pressure" I was talking about the garden hose pressure...but I have 2 related questions:

1 - Why does Honda tell us not to run the motor while using the flush attachment?

2 - Exactly how deep in the water does the lower unit need to be for the pump to pick up water properly? I've been submerging it up to the tops of the intake ports with no luck,

nmar - That occurred to me - I haven't tried the infra-red thermo but when it "overheats" the manifolds are too hot to touch...I'll try it though!

If you're not getting any water pressure and no pee stream while running the motor in the tub, I suspect you are actually overheating and it's not a sensor issue. But it won't hurt to check.

But first I would increase the water level in the tub. For the tub level, I like the water level to be about at the antiventilation plate or higher. The pump is on top of the lower unit so the intake ports are quite a ways below it, so I think the pump has trouble priming if the water isn't high enough.

wildebeest - yeah, that occurred to me too - now I'm definitely gonna try a different tub w/ more/higher water - thanks!

When fully warmed up, manifold temperature should be 160 F. T-stats don't start to open until about 130 F.

Thanks Chawk - that's very good info - at what temp does the manifold temp become "overheated"?

I'm not sure. BUT, it's the block temp sensor (ECT) that will force the engine into LIMP mode and shut it down. Per Ian6766, normal block temp is between 90 and 100 deg C (194 to 212 degrees F.) The alarm is triggered at 110 deg C. (230 F)

The block temp sensor is located in the V between the two heads, and it requires the removal of at least one of the heads to get to it.

Thanks again Chawk - I'm armed with lots of new info/tricks for my next session with the motor!

Today was one of my weirdest sessions yet - but I'm calling it a small miracle...

Since I didn't have a tub big enough to submerge my LU up to the A-V plate, I dropped my LU again & hooked my garden hose directly to the water tube & started it up - the port side manifold at the temp sensor stayed about the same temp as my well water - about 55* - the starboard manifold went straight up to 185*, the alarm went off & then it shut down - thinking I might learn something about how my sensors were functioning, I switched them around & started it up again - this time, neither manifold went above 70* & it never went into alarm - I then put the thermostats back in & started it back up with the hose still attached - both manifolds never went above 130* & it still never over heated!

I realize it doesn't make sense to think that just swapping my temp sensors around would fix my overheating problem - I'm guessing that the direct flushing I gave the motor cleared a blockage? Anyway, I'm confident enough that my pump is working properly, that I'm going to launch her & see what happens...

If the saga continues, I'll give an update - thank you all for your valuable insights - I hope I have an opportunity to help someone else out in the future - Happy Trails!

It is also possible that by switching the sensors, you cleaned off some corrosion on the connectors and got a better signal.

I was thinking that or maybe I knocked loose some crud inside the manifold when I pulled them - regardless there was a dramatic drop in temp on the starboard side of the motor...thanks again!