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Newer Honda BF250 Question

D

doc_stressor

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I'm considering repowering with a Honda or Tahatu 250 hp engine. I've been told by a dealer that Honda has made some changes in the 2018/19 model year that includes the elimination of oxygen sensors. While I know that these have been problematic in the marine environment, I'm concerned that the engine can no longer sense engine load. This can lead to the engine running rich under certain load conditions and contribute to fuel dilution. Oil making at low speed is why I'm thinking of replacing my current Yamaha F250. I need an engine that will let me troll without filling up the crankcase every 20 hr.

Has anyone had experience with the newer Hondas? Has anybody noticed if they make oil? And how is the fuel economy relative to the older models?
 
I wouldn't worry too much about that, Honda only make engines better with new models, and more fuel efficient, they would have other ways of controlling fuel economy.
 
Just to add to what I said, whilst I have not seen the new motors I know someone who replaced his old 225's with the new ones and says they are fantastic and super fuel efficient.
 
Hi doc_stressor,
Welcome to the Forum.

I don't work on the big Hondas but I have an extensive background in engine repair and diagnostics.

I'm guessing that you may be hearing about the oxygen sensor (O2) going the way of the dinosaur. Many O2 sensors have been replaced by true air/fuel ratio sensors (A/F). A/F sensors allow for more precise reporting to the computer about what is actually in the exhaust stream. This should allow for more precise fuel control over all engine operating conditions.

I have also been looking toward the day that outboard manufacturers can figure out how to incorporate Mass Air Flow (MAF) measurements in the marine environment and move away from the less accurate speed density method that utilizes manifold absolute pressures (MAP) to calculate air induction. Maybe that day has arrived at Honda. It wouldn't surprise me if it has, Honda being one of, if not THE best outboard builder.

Like the other guys here have said, Honda has likely improved performance in their latest offerings.

But, I have no firsthand knowledge of this so it's speculation on my part.

Let us know if you find any interesting information on this subject.
 
So maybe they just replaced the old 02 sensor with a broad band A/F sensor, which they have been using in their cars and trucks for a long time? That would make sense. It would require a change to the ECU as well. I was curious how they could still advertise lean burn technology without a sensor in the exhaust.

The making oil problem I have with my F250 is not uncommon in V6 Yamahas, even the new ones. I've gone around with Yamaha over this issue for many years. The possible causes they suggest are 1) over propping; 2) leaking fuel injectors; and 3) too gentle a break-in, which fails to properly seat the rings.

I am guilty of #1 and #3. The boat came with a 19" prop that wouldn't turn more than 5400 rpm at WOT. I switched to a 17" after the first 100 hr, which would turn 5700 rpm. I had a shop take out an inch of pitch so that it now turns 5900 rpm at WOT. I followed the break-in procedure listed in the owners manual, which was very gentle for the first 3 hr. But the shop manual, which I didn't get until after 100 hr, listed a very different break-in method. They want you to run the engine for 1 minute intervals at WOT every 10 minutes during the second hour of operation. Interestingly, this is what Mercury included in their owners manual back when they sold re-branded Yamaha V6 4-strokes. My engine passes the injector leak down test and the compression is fine. It runs great and is fuel efficient. But if I troll or run at less than 4400 rpm in rough seas, the oil level increases. And I mean increases a lot. I once fouled a set of plugs after 75 hr because the level got so high the oil was getting through the crankcase breather into the intake manifold. So I end up either removing oil or replacing the oil every 50 hr or so. But back in December, I decided to screw and trolled for 10 hr. I measured the oil I removed and learned that it had increased in volume by 3/4 quart from fuel dilution.

While Yamaha won't admit it, the absence of an 02 sensor could also contribute to the problem since the ECU has no way of determining if the engine is running rich under load and must rely on a pre-programmed fueling profile. So that's why I was concerned when I was told that Honda was doing away with the 02 sensor on the BF250.
 
With all the Yamaha's that are in service that were never broken in by the book, I would say yours has a unique issue... An O2 would not make a difference in your situation.

I would have a leak down test performed on your engine, a leak down with the piston moved slowly down the bore to check the whole cylinder.

Anytime I have seen a Yamaha make oil was from incorrect/low engine running temps.
 
Making oil is a very common problem down here (Homosassa, FL) where there are lots of long no-wake zones and people do a lot of trolling. It seems like half of the working age population down here works at a boat dealer or repair shop. These guys tell me that most people with the problem aren't even aware of it because they never check their oil. But when the shop changes oil they often find the level a couple of inches above the full line. Mine does seem to be an extreme case, however.

I have done everything you suggested with this engine over the past 9 years. Tested and changed the thermostats, replaced the pressure relief valves, monitored temperature, and done several compression and injector leak down tests. Everything seems normal. Yamaha said that they would replace the powerhead when the engine was under warranty, but I needed to show an excess of 7% fuel dilution before they would do that. I never had an oil analysis result come back that high. But I was using Blackstone, which uses flash point depression to indirectly measure fuel dilution. That's not a very accurate way to measure fuel content.

In any case, I'm done with this engine. If somebody puts it on a light boat and runs it hard all of the time there would be no problem. But I'm going with a Honda/Tahatsu. I trust that any changes in the new BF250D engines have been well vetted. I've had Hondas in the past and they were all great engines. One trolling did make oil occasionally, but only when the thermostat would fail in the open position.
 
Can't speak for the 250, but I troll with my 2007 BF 225 A LOT, like 6 - 7 hours at a time and have never had the problem of "making oil." At over 2100 hours, I think that says a lot for how Honda puts these engines together. Just maintain them well and they will give you a lot of trouble-free hours.
 
I found a parts blowup of the BF250 exhaust manifold and sure enough, there was no O2 sensor. So I shot off an email to Honda and got this reply:

[FONT=wf_segoe-ui_normal]Hello Lee,
[/FONT]
[FONT=wf_segoe-ui_normal]The current product BF250 "D" models do not have the 0-2 sensor, any other BF250 other than the "D" model will have an 0-2 sensor.[/FONT]
[FONT=wf_segoe-ui_normal]Engineers have been able to achieve fuel monitoring with the other sensors on the engine to keep the lean burn and fuel economy as a priority for the marine side of the larger engines Honda produces.
[/FONT]
[FONT=wf_segoe-ui_normal]We hope this helps, thank you.[/FONT]
servlet.ImageServer
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So they must be using data from the throttle position, tachometer, temperature, and MAP sensors to estimate combustion efficiency. That what Yamaha does. I hope that their algorithm is better. Honda has some of the best automotive engineers in the world. I hope that this expertise trickles over to the marine division.
 
Not monitoring exhaust content at all would have me wondering about how do they achieve "lean burn" parameters? I don't know if I
would be comfortable with knock sensors being utilized for normal fuel control. Especially in very warm operating conditions.
But, then, you could make a whole new world out of the stuff I don't know.
Any idea about how Yamaha does it?
 
We have sold 100+ units of BF250 in Indonesia. These engines are great, customers are very happy. Fuel efficient, fast, low cost. If these engines are operating long hours against strong current then problems may appear such as thrust washer. Mostly 30inch type. Overhauled engines will not last more than 200hrs for commercial use. For regular use, (fishing, short duration less than 4 hours) these engines are great.. Great engines but need good technicians to repair. To be on the safe side, 25inch last longer. Some engines still run great after 3600 hours (daily use of 6 hours roundtrip) with good maintenance service..
 
Jackspeed999 - thanks for the info. Thrust washers failing after 200 hours? That's a BIG red flag!!! Thought Honda fixed that issue on the 225's. Would like to hear from other 250 owners.
 
I recently bought a boat with a 2015 BF250 w approx. 650hrs. Just out of warrantee and am now chasing down o2 sensor issues. Theres some info out there on the 225 o2 sensor issues and sensor replacement but not much on newer 250's. Does anyone have more insight to this not uncommon problem?
 
It's the same issue, no real answers other than rrplacement when failure occurs. Honda jad no real fix which is the reason they have deleted it on their new motors.
 
I noticed that this thread has been brought back and I want to let everybody know how satisfied I am with my BF250D. It will troll all day without making oil and the fuel economy is excellent. It does about 20% better than my old F250 at high cruise. I could squeeze 3 mpg out of the F250 as long as I didn't run over 4100 rpm (27 mph). The Honda stays in ECO mode up to at least 4700 rpm (32 mph) and gets 3.1 mpg if it isn't too rough. The F250 would only get 2.5 mpg at that speed. I'm using the same 16" prop I took off the F250 on the Honda. It also doesn't jump back and forth between ECO and BLAST mode when you are close to the limit like a lot of older Hondas do. There isn't anything I dislike about this engine except that it is BIG!
 

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Good to hear. If I ever re-power, I plan to either do a 250 or dual 150's. My old C-Hawk (which is a heavy old beast) is rated for 300 HP.
 
I'm running that engine on a 2008 Grady White 226, FYI. The SV2 hull is a push through the waves type rather than riding on top. It's not particularly fuel efficient.
 
SoFlaMk, man, oh man, it seems each owner has different experiences. In my case I end up replacing the O2 sensors on my twins each season. I found another post where another guy experiences the same thing: www.marineengine.com/boat-forum/archive/index.php/t-446930.html post from metal-chicken at
06-30-2019, 12:04 PM
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For two years running now, the O2 sensors have failed on both engines after not using in the low season plus the odd one here and there, same as metal-chicken, and in case you are wondering:
Engines are 2011, post SB 56. No, I don´t have water in my fuel. Yes, I get off the plane gradually. Yes, engine exhausts are above 6" from the water. No, I don´t pour water down the exhaust or wash down the engine casing without care or with a hot engine to avoid steam in the exhausts. Yes, I run the engines each two weeks in low season to normal operating temperature. No, I don´t conserve and spray oil into the intakes at the end of high season. No, it is not wiring. Yes, I reset the ECU after replacements. Yes, failures confirmed with fault code and Dr. H. Yes they really are failing and it´s nothing else, with rough idles kicking in before the alarm, O2 fault code, O2 in Dr. H. and high fuel consumption in my optimum cruising range which is between 3400 and 3600 RPM which goes from 22 litres/hr per engine (my normal) to 26 litres/hr which is not normal with my layout.

Sorry for the tone, but I am fed up with this issue. I replace the sensors, engines run great, everything goes back to normal and I am normally good for another season. I´m even wondering if heavy rains and wind can accumulate water in the exhaust with the engines up. Original Honda O2´s give me the same result as Walkers, so I buy Walkers. Just poor engine design somewhere, but not able to identify why it affects some operators while others are not.

I tore down one of the broken ones last week, carefully cutting into it, looking for traces of salt, water marks, etc, but no findings...


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I am starting to wonder if I end up having to cough up $200-ish a year for O2 sensors, vs. $20k for a new motor, maybe I am not doing too bad - LOL.
 
Blacktimes - Interesting! I have a 2007 BF 225 with the old style (22 mm base) HO2 sensor. After 2200+ hours, the original sensor is still good to go according to pulling fault codes, which I do every 100 hours. And I do a LOT of slow trolling.

It's just crazy to see the different experience folks are having with HO2 sensors on the 200's, 225's and 250's. Back to my industrial engineering days, that tells me there is a serious quality control problem with their supplier, which Honda never wanted to really own up to. I'm certainly glad they have done away with them on the new models.
 
chawk_man said:
Blacktimes - Interesting! I have a 2007 BF 225 with the old style (22 mm base) HO2 sensor. After 2200+ hours, the original sensor is still good to go according to pulling fault codes, which I do every 100 hours. And I do a LOT of slow trolling.

It's just crazy to see the different experience folks are having with HO2 sensors on the 200's, 225's and 250's. Back to my industrial engineering days, that tells me there is a serious quality control problem with their supplier, which Honda never wanted to really own up to. I'm certainly glad they have done away with them on the new models.
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I sure wish there was a mod that could be done so as to allow us owners of motors with O2 sensors to get rid of them - LOL.
 
I have been looking around, found some lambda extenders but they are for M18 sensors, the -C01's are M10, wouldn't mind a 90° vertical installation to see if that would make a difference considering that it could be water or humidity related. In any case, from reading many posts my main conclusion generally speaking is that the old -013 sensors were way more reliable than the new -C01 sensors. The old ones were much cheaper too.
 
doc_stressor said:
I noticed that this thread has been brought back and I want to let everybody know how satisfied I am with my BF250D. It will troll all day without making oil and the fuel economy is excellent. It does about 20% better than my old F250 at high cruise. I could squeeze 3 mpg out of the F250 as long as I didn't run over 4100 rpm (27 mph). The Honda stays in ECO mode up to at least 4700 rpm (32 mph) and gets 3.1 mpg if it isn't too rough. The F250 would only get 2.5 mpg at that speed. I'm using the same 16" prop I took off the F250 on the Honda. It also doesn't jump back and forth between ECO and BLAST mode when you are close to the limit like a lot of older Hondas do. There isn't anything I dislike about this engine except that it is BIG!
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