Logo
FULL SITE MENU

BF30A overheating?

S

Samav

Contributing Member
Hey guys, I'm not sure if this is actually a problem or not, but my bf30a Honda outboard seems to be overheating. After running for only about 10 minutes the lower unit and engine block are both too hot to touch for more than a few seconds. Not sure if this qualifies as overheating, or even if this is a problem, but I figured better safe than sorry. The water cooling system seems to be working ok, and the tell-tale runs strong when idling. The tell-tale water isn't even very hot while the motor is running, it only ever gets to a lukewarm temperature. Here are some pictures.
image1.jpg
The motor idling
image2.jpg
This water exit port seems to have trouble pushing water out when idling. Not sure if that means something is blocked or not
image3.jpgimage4.jpgimage5.jpg
These are the sections on the motor that get pretty hot, except for the carburetors themselves.

Do I need to inspect/replace the impeller, or do you guys think something else could be going on? Thanks for all your help in advance.
 
Given your tell tale is strong, your impeller is pumping water up, I would pull your thermostat and your water inlet cover, which are both right next to your spark plugs, it is the piece between the oil filter and the spark plugs. Thermostat is on top and then remove the 6 or so bolts for the inlet cover. You may have a clog or your thermostat is stuck.

Never hurts to inspect at minimum your impeller if it hasn't been done in a while, you may still get water but it could also be within an inch of its life.
 
It appears in one of your pictures that you are running it on ear muffs. I can not see any tape on the lower unit covering the water pickup under the horizontal fin just above the propeller. It looks like a lot of water is coming out there.

It that intake is not covered, the impeller is sucking air as well as water and may have a good telltail, but not enough water flow through the engine. The engine could overheat that way and the impeller can get damaged.

The thermostat opens around 168 deg F and is fully open at 180 deg F. That feels pretty hot to my little pinkies.

If you can find an inexpensive temperature gun, like this one, you should check the temperature at the thermostat housing. https://www.amazon.com/Etekcity-Las...pID=41xO8jWPMwL&preST=_SY300_QL70_&dpSrc=srch

As Eneusiis suggests, if the impeller has not been changed/checked recently or ever, it might be a good time to do so...even if the temperature is in spec.

Mike
 
Thanks for the help guys. I will do an impeller inspection soon and let you guys know what I find. @hondadude, do you mean that the ear muffs aren't covering the water intake properly, allowing some air to get in with the water? If so, what would you recommend I use instead of the ear muffs?
 
I appears that your earmuffs are fine. If the raise the engine up and look under the horizontal fin, just above the propeller, you will see a third small water intake. It is right in front of the trim tab.

That third water intake needs to be sealed off with some duct tape.

Mike
 
Well I just inspected the thermostat...and it did not look pretty. For some reason I can't upload pics onto the forum right now, but here is a link to the pictures: https://imgur.com/a/T0OGp

The gasket was very brittle and basically falling apart, it peeled in half as I took the thermostat cover off. There was a lot of salt build up and corrosion. It even looked like there was some oil leaking out of the thermostat cover?? And to top it all off, the thermostat didn't open when I put it in boiling water. I think we found the problem haha. Would very much appreciate some feedback and what to do at this point, as I am quite new to working on outboards. Obviously I will have to replace the thermostat and gasket, but what should I do about the major salt build up and gasket that is literally sealed onto the powerhead?
 
Also, what are the implications of this problem? Could I have easily overheated the engine to the point of warping something important? Should I take it to a person who knows what they are doing? SO MANY QUESTIONS..sorry guys, I'm just worried.
 
Go over to www.boats.net and order up your new thermostat, thermostat gasket and a new water inlet cover gasket. If you want to get rid of the salt a brush and 50/50 water/white vinegar will take care of the build up. If you want to clean it properly, clean the water inlet, which is why I said above order the new gasket. It is the vertical cover below the thermostat and between your oil filter and spark plugs, held on by 6-8 10mm bolts. Clean in there as well. Replace all things, then I recommend getting a cheap trash can versus muffs. Fill the trash can with water, including keeping the hose running and let the motor run. This way you don't have to deal with duck tape using the muffs. Run it a while and see if it gets as hot..my bet is it won't.
 
Back
Top