BF 90 - Overheating

[pbrthe2]

My 2000 BF 90 is overheating. The problems started back in December. I removed and replaced the impeller. I removed and replaced the thermostat. I took apart the valves and cleaned them out. I took it to the Honda dealer, and they said they cleaned out a poppet valve that was clogged. I hadn't run the engine more than an hour at a time since then. No problems, except recently, the engine has been overheating again while cruising for 40 minutes+ and 3800 to 4500 RPMs in the afternoon sun. I took apart the relief and flush valves and cleaned them out. (I don't think the flush valve has any significance other than when using the flush assembley). The output coming out of the p*sser is strong at idle and is extremely strong when I bump up the RPMS.

I was looking at this diagram while I was taking everything apart:

http://www.boats.net/parts/search/Honda/Outboard%20Engine/2000/BF90AY%20LRTA%20MARINE%20ENGINE%2C%20JPN%2C%20VIN%23%20BBBL-4200001/THERMOSTAT/parts.html

Could the thermostat I was sold be bad, and is not opening up?

I have heard that an engine block can suck air and cause this problem, but a mechanic said that was an unlikely problem at around 800 hours.

I also have a stall issue, which I posted separately, and I believe (???) is unrelated to this.

Any ideas where to go from here?

 

[dtj]

Re: BF 90 - Overheating

My 2000 BF 90 is overheating. The problems started back in December. I removed and replaced the impeller. I removed and replaced the thermostat. I took apart the valves and cleaned them out. I took it to the Honda dealer, and they said they cleaned out a poppet valve that was clogged. I hadn't run the engine more than an hour at a time since then. No problems, except recently, the engine has been overheating again while cruising for 40 minutes+ and 3800 to 4500 RPMs in the afternoon sun. I took apart the relief and flush valves and cleaned them out. (I don't think the flush valve has any significance other than when using the flush assembley). The output coming out of the p*sser is strong at idle and is extremely strong when I bump up the RPMS.

I was looking at this diagram while I was taking everything apart:

http://www.boats.net/parts/search/Honda/Outboard%20Engine/2000/BF90AY%20LRTA%20MARINE%20ENGINE%2C%20JPN%2C%20VIN%23%20BBBL-4200001/THERMOSTAT/parts.html

Could the thermostat I was sold be bad, and is not opening up?

I have heard that an engine block can suck air and cause this problem, but a mechanic said that was an unlikely problem at around 800 hours.

I also have a stall issue, which I posted separately, and I believe (???) is unrelated to this.

Any ideas where to go from here?

For the thermostat, put it in a pan of boiling water and see if it operates........Don

 

[cp]

Re: BF 90 - Overheating

You've addressed, presuming you used the correct parts and did a good job, the most common causes of overheating: the water pump and the thermostat. What leads you to believe your BF90 continues to overheat? Are you getting an overheat alarm - continuous beeeep - and accompanying automatic reduction in rpm? Or are you seeing some other symptom - what?

 

[reelhigh]

Re: BF 90 - Overheating

i have the same problem, buzzer goes off af
ter running for a while, rpm goes down, take out of gear for 5 sec, put back in gear and go for a while again, somtimes 10 min, sometime 30 min. can it cool down that fast, or is it not realy running hot.

 

[pbrthe2]

Re: BF 90 - Overheating

There were some distractions for me to finish this problem. I am back working on it. I pulled everything apart. I am going to give this one more shot before taking the motor back to the shop. (A different shop, though. The last one "fixed the problem" by cleaning a poppet valve. The poppet valve they cleaned appears to prevent the cooling system water from going out the freshwater flush adapter on the back of the engine.)

Symptoms: The overheat alarm goes off, continuous beep, with an automatic reduction in RPMs. I idle for a few minutes, hop up on plane and go maybe another 10 minutes before the alarm and auto reduction go off. The odd thing, is that I have sometimes run the engine for several hours before the the alarm and reduction occurs.

I hope I used the correct parts, the parts guy at a local Honda marina gave me them. Of course, the guy told me it would only take a quart of lube for the foot, and he was short by several ounces.

I dropped the thermostat into a jar of hot water (~140 degrees). The thermostat opened.

 

[pbrthe2]

Re: BF 90 - Overheating

Here's a picture of the impeller in the housing. It looks like its curled in the right direction.



Here's another form a slightly different angle.



I believe I have the right side of the poppet in the spring:

 

[pbrthe2]

Re: BF 90 - Overheating

see below

 

[pbrthe2]

Re: BF 90 - Overheating

From what I can tell, it looks like the water goes through the lower poppet valve, comes up through the bottom part of the thermostat housing (which is exposed in the picture below), and when the thermostat opens, the water runs through the engine.

 

[pbrthe2]

Re: BF 90 - Overheating

Any ideas of other places to check for blockage?

 

[pbrthe2]

Re: BF 90 - Overheating

Any chance the sensor needs to be pulled? Is this something that can get gummed up and needs cleaning, or is it a remove and replace item?

 

[pbrthe2]

Re: BF 90 - Overheating

Guys, I need some help. The ladies are asking if the boat has been fixed, yet.