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Honda BF250 running hot?

S

Sarrre

Contributing Member
Hello guys,

Do you know what is the normal working temperature for the Honda 250? One of my customers is afraid it's running too hot. According to the instrument data it is between 176°F and 195°F at 4000 rpm. When going back to idle speed, the temperature goes down to 158°F-167°F. The engine is never warning for overheating, but compared to other engines it seems too much. I have no experience for this model.
 
Verify the overheat with an IR heat gun.

Not sure about the 250, but for all of the other large Honda's (225, 200, 175) the operating temp should be 160 F across the entire operating range. First pull the thermostats and make sure they are working correctly. Put them in a pan of water and heat to 160 F. They should be fully opened at that temperature. For the other engines, fully open is 3 mm. I suspect that the 250 is the same. Remove the lower unit and inspect/replace the impeller on the water pump. Depending on hours, it may be best to replace the entire water pump - it's not much more expensive than the impeller kit.

When you pull the old impeller, inspect it closely for missing vanes of chunks of rubber. They can get stuck in your cooling passages.
 
The engine is brand new, so the impeller should be ok. Do you know how Honda measure the temperature? Do they mesure the engine block, oil temperature or water temperature? I checked the service manual for information, but it doesn't say anything about working temperatures.
 
On my 225 there are heat sensors on the top of each manifold right near the thermostats. They are pretty obvious. They are resistance-type sensors. As they heat up, ohms drop. If the 250 has the four prong service connector like the 225, there is a procedure for pulling fault codes that will tell you which sensor is giving you the overheat fault. Send me an e-mail at [email protected] and I will send you the procedure for getting fault codes and a file telling you what the fault codes are for the 200/225. Not sure they are the same for the 250.
 
I did not buy this engine in my country, so it is too far away going to the dealer for something that is maybe not wrong. I just want confirmation if the temperature is normal or not, and the dealer do not have any experience with this model.
 
If the thermostats check out, I would still go ahead and pull the lower unit and thoroughly inspect the water pump. Assembly in manufacturing can sometimes go awry. The impeller could be in backwards, the lock key may be not in correctly, a vane could have failed, etc. etc.
 
I see. Thank you for the advice chawk_man.

If someone has information about the normal temperatures for this engine, please let me know.
 
In the US we can call Honda directly. Before doing anything, I would try to call a Honda dealer, rep, or customer service somewhere and get accurate info on normal operating temp.
 
Engine temperature displayed on my Lowrance GPS and LMF-400 are inline with the temperatures you have posted. I believe the temperature displayed is from the EBT (engine block temperature) sensor not one of the ECTs (engine coolant temperature) sensors. This would be essentially oil temperature. At WOT my temperature indication is ~215 degrees. I assume this is normal. I have not found a way to display the ECT on the GPS.
 
Hi, I have twin 250s. Both display about 85 Celsius at 4,000 rpm which is similar temp as you have. Other BF250 owners have same results and I be been told by engineer this is normal operating temperature.
 
Corsair33 said:
Hi, I have twin 250s. Both display about 85 Celsius at 4,000 rpm which is similar temp as you have. Other BF250 owners have same results and I be been told by engineer this is normal operating temperature.[/
Two BF250 with 250 hours. Had 200 hour maintenance including water pump, impeller and housing. Usually see 200f at 4800-5100 rpm.


Yesterday after about 30 min of running at 4800 rpm i noticed the port engin's temp started showing 10-20f lower on one mfd screen display On the same mfd but another screen both engines were at 200f. Then about 4 hours later after multiple starts and slow rpm cycles (changing fishing spots) the port engine showed 20f below starbord at rpm under 2000 rpm and was 10F below historical and starboard engine temp at 4800 rpm. Rpm and battery display on mfd was normal.

Russ PandelOffice 202 640 1957
Cell 321 213 3663
Click to expand...
 

Two BF250 with 250 hours. Had 200 hour maintenance including water pump,impeller and housing. Usually see 200f at 4800-5100 rpm.


Yesterday after about 30 min of running at 4800 rpm i noticed the port engin's temp started showing 10-20f lower on one mfd screen display On the same mfd but another screen both engines were at 200f. Then about 4 hours later after multiple starts and slow rpm cycles (changing fishing spots) the port engine showed 20f below starbord at rpm under 2000 rpm and was 10F below historical and starboard engine temp at 4800 rpm.
 
Is that temp from a test tank or water hose? Those big engines will run a bit hotter on a garden hose because of the large amount of water needed to circulate inside the heads and block, at least thats my experience with my 200s
 
Skooter said:
Is that temp from a test tank or water hose? Those big engines will run a bit hotter on a garden hose because of the large amount of water needed to circulate inside the heads and block, at least thats my experience with my 200s
Click to expand...
.

The temps are from running the boat in the indian river.
 
To all the 250 owners who posted on this thread - There have not been that many postings on this forum about the the 250's. Hopefully that's a sign that they are having few problems.

I think a lot of folks that monitor the forum would like to know as much as possible about them. Many owners of the 200's and 225's are probably thinking that if they need to re-engine their boats, the 250 may be a good choice. So please take the time to post any discoveries, surprises, or issues with those 250's. Thanks.
 
UPDATE:
Original post:

Two BF250 with 250 hours. Had 200 hour maintenance including water pump,impeller and housing. Usually see 200f at 4800-5100 rpm.



Yesterday after about 30 min of running at 4800 rpm i noticed the port engine's temp started showing 10-20f lower on one mfd screen display On the same mfd but another screen both engines were at 200f. Then about 4 hours later after multiple starts and slow rpm cycles (changing fishing spots) the port engine showed 20f below starboard at rpm under 2000 rpm and was 10F below historical and starboard engine temp at 4800 rpm. Pee pressue seemed lower on port. cleaned with 80# mono and it's still weaker than the starboard.

UPDATE:
We took the boat out for a river fishing session yesterday. Started with port 10F lower than starboard. Pee pressue was still not as strong as Starboard. Cleaned with 80# mono. no change.

Noticed that after running 10 min at 4800 rpm and then slow motoring to an anchor spot the temp of the port engine now increased by 10 F and matches the starboard at 190F. Back at the dock I again cleaned the pee tube with 80# mono. Now the pee stream is very strong and matches the starboard engine.

Glad it fixed itself but what was going on?
 
I know this is an old thread but figured I would add to it . I just installed 2 bf250d hondas on a 282 center console. The port, counter rotating motor, runs 2 degrees higher than the strb. 178 to 198 at 4600 rpm. These motors have have 200 hrs on them and the pump impellers are brand new. I reach WOT of 6300. Water temp was 66 degree. In florida my concern is when that water gets to be 80/85 dgrees is that going to effect the running temps. Would be nice to get some data on running temps. Why does the port run hotter than the strb? What considered hot on these motors. Anyone else seen this or have more experiance with it? Thanks
 
I too would like to know if its normal that the nmea2000 reading of temp in my bf225 is between 90 -98 degrees celsius? no high temp alarm and normal cooling water flow. New impeller and waterpump housing.
 
Ian, from Australia, posted this a few years ago...

"The manifold sensors typically run around 60 deg C (140 deg F) and the block sensor between 90 and 100 deg C (194 to 212 def F.)

The alarm and guardian is triggered at 110 deg C. (230 F)

I have found a lot of saltwater engines creep up over the years as scale builds up inside the water jackets.

The reading shown on NMEA digital gauges is the block temp.
 
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