outboard (Honda BF50A) overheating 1st day out

[Tomfoolery]

I've never had to do it, but on the inboards my FIL had (60 year boater), he tells me that he's had to take apart the heat exchanger (fresh water cooling), and a lot of the plumbing, and force water through the passages backwards. On a raw water cooled outboard, I would imagine it's the same drill, without the heat exchanger.

Someone who's actually done it to an O/B would be a better person to give specifics, like an O/B mechanic. My FIL put the fear of God on me about having an impeller come apart, so I've been careful to not let them go more than 2 years. They probably last longer, depending on how much use they get I suppose, but I'm not willing to test it.

Have you tried running the O/B on the trailer, with a garden hose providing water? You should be able to see how much water is coming out through the prop hub, and what the temperature is. Are you sure the inlets aren't clogged? Pee hole engine-side fitting, hose, and end fitting clear? Thermostat working properly? Temperature sender working properly? Not trying to be snarky - just obvious things that come to mind that need checking.

[NiceAft]

Dave,

I just want to mention that don't hold it against the mechanic for not replacing the impellar.

As for the current problem, instead of futzing around trying this and that, you may just want to take it back to the same guy who winterized it. If the boat is at a slip, does the guy make dock calls

Ray

[DaveB]

Fill a 40 gal. trash can and fill it with water and add one quart of white Vinegar. Disconnect the pee Hole from block and put in a fitting large enough so you can attach a 1/4 inch ID line to it and start the engine until you feel about 100-120 degrees comeing out pee hole. This should clear debree in water jackets.
Than shut off engine and let set for 1/2 hr.
Restart and run for 5 min. than empty 40 gal. and put in all fresh water and run for 5 min.
Change your pee hole fittings to 5/32 ID.
The Honda flush connection is not a total flush.
The Vinegar will help clear waterways tru engine without causeing harm.
I am assuming you replaced the Termostat.

Dave

. Too hard to get the pieces out of the passages once it comes apart, which may be what happened to yours.

So how *do* you get them out?

[DaveC426913]

...just obvious things that come to mind that need checking.

Well, nothing's obvious to a novice.

[DaveC426913]

Well, I'm stumped.

Took the water pump apart to see if maybe I'd installed it wrong. Seemed OK. Cleared out the pee-hole. There's still nothing coming out of it.

Tried for an hour to see how I might flush the cooling system. Found nothing.

At this point, I'm ready to call it quits. I'm going to call around to my local outboard mechanics and see if anyone does housecalls. $$ $$

Dave,

I just want to mention that don't hold it against the mechanic for not replacing the impellar.

No. I asked for winterizing, not general maintenance.

But I do hold it against Honda. If replacing the impellor is considered a maintenance task, it should be in the owner's manual.

As for the current problem, instead of futzing around trying this and that, you may just want to take it back to the same guy who winterized it. If the boat is at a slip, does the guy make dock calls

Ray

Sort of out of the question at this point. Mast is up, trailer's back at storage. I'd have to get it back to the public ramp to pull it out, and I can't get it back the public ramp without an engine (I could, but I wouldn't want to try.) The whole procedure would set me back a week.

[Phil M]

On a day or morning with a light breeze, you should be able to approach fairly close to a shore or ramp without using a motor. That is one of the good things about our sailboats. It is possible to move them withou an engine.

[Catigale]

Dave

Was your impeller in pieces or did it look ok?

Have you replaced the thermostat?

[DaveC426913]

Dave

Was your impeller in pieces or did it look ok?

The old one was, yes. Clogging is my best theory going. But I don't have the skills or instructions to fix it.

Have you replaced the thermostat?

No. That's the disk, high on the starboard side, yes? Maybe not a bad idea.

But I'd need a special set of tools just to get it off.

Still, that can't be the problem, can it? If I'm not getting any water out the pee-hole, then I'm not getting any cooling.

[DaveC426913]

Went back for more punishment.

Checked the t-stat. It was a little crusty but I was able to pop it open and closed. I didn't temperature check it. Other than some buildup, there was no bits of impellor lodged in it.

Started the engine up with the t-stat cap off. Got a nice gush of water. Checked the pee-hole exit tube. It was indeed plugged with a bit of gloppy sand.

Put it all back together, restarted the motor and got a nice thick stream from the pee-hole. So I took it out for a spin. No joy. Got up to top speed and the alarm went off again. Throttled back to dead slow till it went off.

I raised it 500rpm at a time till the alarm went off - around 4500. Which is pretty respectable. Certainly passing any other sailboat on the lake. Shouldn't complain. But I don't want to leave it like this. Don't want to be "nearly overheating" every time I go out.

By the time I got it back to the mooring, the pee-flow had all but dropped off to a dribble. Another reaming and it was better.

Must be impellor bits / sand jammed way up inside the block. Just enough to block flow at high speeds.

Question: should the inlet ports be roiling air and water while in neutral? Seems to me that's a lot of stuff coming *out* of a place where stuff should only be going *in*.

[mk1]

in addition to all other excellent suggestions posted here and in the other thread referenced above, there is one other problem I had encountered after replacing my impeller and the indicator. The thermostat on my BF50 was frozen solid in closed position by salt deposits and had to be rplaced. Fortunately it is very easy to do. Once you find where it is it only takes a few minutes. I also used liberal amounts of saltaway spray to break down salts inside the passages under the thermostat and flushed for about an hour. You have to tape the water intake above the propeller to flush properly.

Have been running for a while, a few hundred hours at least without any problems since.

[Catigale]

Replace thermostat
Replace temperature sensor

Keep flushing. Is the motor getting hotter than before ?

[Tomfoolery]

I raised it 500rpm at a time till the alarm went off - around 4500. Which is pretty respectable. Certainly passing any other sailboat on the lake. Shouldn't complain. But I don't want to leave it like this. Don't want to be "nearly overheating" every time I go out.

It may actually BE overheating in one or more areas at lower power levels, depending on where the obstruction(s) is(are), just not where the temperature sensor is. I wouldn't run it any more until you get the passages cleaned out, which may require more dismantling, unfortunately.

But it would stink on ice to do serious damage to one cylinder (for instance) because the temperature at the sender was below alarm levels even though it was elevated in one or more local areas. Or crack the block or head from differential thermal expansion it wasn't designed to tolerate (very hot in one area, very cool in another). I wouldn't mess around here, though that's easy for me to say when it's not my labor and/or money involved.

[DaveC426913]

The thermostat on my BF50 was frozen solid in closed position by salt deposits and had to be rplaced. Fortunately it is very easy to do. Once you find where it is it only takes a few minutes. I also used liberal amounts of saltaway spray to break down salts inside the passages under the thermostat and flushed for about an hour. You have to tape the water intake above the propeller to flush properly.

Have been running for a while, a few hundred hours at least without any problems since.

Only used in freshwater.

[DaveC426913]

I raised it 500rpm at a time till the alarm went off - around 4500. Which is pretty respectable. Certainly passing any other sailboat on the lake. Shouldn't complain. But I don't want to leave it like this. Don't want to be "nearly overheating" every time I go out.

It may actually BE overheating in one or more areas at lower power levels, depending on where the obstruction(s) is(are), just not where the temperature sensor is. I wouldn't run it any more until you get the passages cleaned out, which may require more dismantling, unfortunately.

But it would stink on ice to do serious damage to one cylinder (for instance) because the temperature at the sender was below alarm levels even though it was elevated in one or more local areas. Or crack the block or head from differential thermal expansion it wasn't designed to tolerate (very hot in one area, very cool in another). I wouldn't mess around here, though that's easy for me to say when it's not my labor and/or money involved.

Hm. You make a good point.

Any care to weigh in on how tough a job it is to pull the cylinder head off myself? I guess, since I'm not an experienced mechanic, it's going to tax my skills. Should consider pro.