Honda BF45 Issues

[bf45]

Hi Everyone, Im new here and hoping we have some Honda outboard experts here. Thanks in advance for any responses!

(My engine is roughly a 1994 Honda BF45a)

Here we go, I've currently 2 issues.

1. After prolonged steady engine speed running I'm getting the overheat buzzer, limp mode and limited revs. this clears after around 30 seconds. I today have done an acid wash, tested the thermostat and inspected the impeller! Ive replaced the impeller, and ran without thermo for testing purposes. I think there is a blockage somewhere as the tell tale stream starts to run warm and then hot, I don't think this should happen... I can't find anywhere a cooling system schematic for this engine to try an identify where the blockage may be, if anyone could help or tell me what to do... I would appreciate it.

2. My starter is running very slow like a flat battery, I have replaced the starter with a new one as I thought the original was goosed. This did not help. I have checked all the obvious, battery has been changed to a huge diesel one to test I have the amps, battery leads are heavy core, solenoid has been replaced. The solenoid is getting hot, the leads are getting hot, the starter turns slowly but does go quick and start it with continual cranking. The engine isn't overly stiff when turned by hand, so I don't believe its internal issues. Has anyone had this issue before?

Many thanks.
Ben

 

[ahicks]

I'm assuming the engine is run frequently in a salty environment. If so it may be up for a thorough cleaning, which is going to involve pulling the head and the exhaust cover. Both jobs not for the faint of heart, but they'll expose the majority the coolant passages for cleaning.

Is there a chance you've blown up a water pump impeller and one of the vanes is blocking the water flow. I've found chunks in and around the water pump itself, and with the lower unit removed, I've had them come out when using compressed air blowing down through the thermostat opening (t-stat and cover removed).

A last ditch effort prior to mayor work may be a descaling program, or filling the engine with vinegar then rinsing the heck out of it. I've heard of all sorts of stuff guys have done. Maybe worth checking out. I have no experience there.....

As far as turning over slow, when you replaced the starter, did you buy an inexpensive Chinese knock off? I've seen those do exactly what you are talking about. I prefer to buy used OEM starters if I'm trying to control expenses. This after making sure my grounds are clean, and both cables are good (not corroded internally).

 

[MattFL]

By acid wash, do you mean something like barnacle buster? Or did you go with regular old muriatic acid? I second what ahicks said about the starter. I tried a cheap ebay replacment starter on my 50HP Honda and it was noticeably weaker than the OEM starter, and it only lasted a few trips. I picked up a used OEM starter on ebay and it was back to normal, maybe give that a shot. Also google around and look for a procedure to test the overheat sensor itself, make sure it's tripping at the correct temperature and not too early. Or just replace it if it's cheap. If that motor is similar to the 1999 50HP, then you can get some access to the cooling passages by removing the intake manifold, assuming the bolts come out easy and don't break off. Not great access, but better than nothing, and maybe you can get an idea for the condition of the rest of it.

 

[ahicks]

Just an FYI (because I haven't seen it mentioned here recently), the 35, 40, 45, and 50hp Honda's built previous to 2007 or so (when they went to fuel injection) are all nearly identical except for minor details. Most of those engine components are interchangeable.... Something to keep in mind when looking for something like a starter!

There's a change to automatic choke (I call it a vacuum line nightmare) at about 2005 that make those carbs unique, but the rest if the motor is the same as the earlier one.

Blocks, cranks, rods, pistons and everything below that are nearly identical. The only change I can think of is they changed the seal on the shift shaft as it comes out of the lower unit from a bellows type to a seal.

From my standpoint, this makes them awesome to work on for all the parts interchangeability.....

 

[bf45]

Everyone!! Thanks very much for your responses. Some great info here. I’ll keep the thread updated on resolution. Thanks again.

just a quick one, should the tell tale ever get warm/hot.. or should it always run cold?

many thanks

 

[MattFL]

Mine gets warm and cool as the thermostat opens and closes when it's on the muffs, but I don't recall it ever getting "hot". By memory, I think it gets cooler when the thermostat opens. It does get hot when it's draining after you turn the motor off.

 

[ahicks]

If it's hot, there's generally something going on....