Honda BF90D Flush Port Clogged

[Dcav66]

I always use muffs to flush my motor, never any issues - it pees fine on the hose and in the water. However, I recently tried the flush port for the first time and no water came out. I followed the owners manual and seems super simple, but zero water comes out. So I completely disassembled the flush valve assembly and sure enough, it was completely clogged up with sand. So I cleaned it out with a small wire and was able to get water flowing from main hose out through the first small metal hose flange/nipple. The little jumper hose was clear, so then I cleaned out the second small metal hose flange/nipple where it goes back into mount case, but still no water flow out the pee hole. Again it pees perfect when I hook up the muffs regularly or in the water. Just not through the flush port. I’m guessing it’s clogged up big time in the mount case somewhere. I even tried to push air pressure from a compressor, but nothing happens - no air or water comes out. Question is where in the mount case could it be clogged up and how do I get it unclogged without taking the whole motor apart? How big of a problem is this if my motor runs fine and pees fine on the muffs or in the water? I am a little concerned because logic tells me if something is clogged somewhere in the mount case then water is not circulating properly which probably means something might not be getting cooled properly. Thoughts?

 

[Sea Rider]

Have you tried flushing the motor through the flushing port with a hose adapter on muffs while the motor idles ON. Or you could flush the motor OFF through the flushing port but will need to remove the thermostat and bolt thermo cap, cover back for the water to recirculate across the whole powerhead.

Happy Boating​

 

[Dcav66]

Have you tried flushing the motor through the flushing port with a hose adapter on muffs while the motor idles ON. Or you could flush the motor OFF through the flushing port but will need to remove the thermostat and bolt thermo cap, cover back for the water to recirculate across the whole powerhead.

Happy Boating​

The way I read the manual is the motor is supposed to be off and water should come out - is that not correct? In my attempts to get the sand out, I ran the motor with muffs with hose connected to the muffs and it peeing as normal. At the same time I had the small flush port jumper hose disconnected trying to see if I could back flush it and/or get water to come out - but nothing came out even after the motor warmed up. I just replaced both the head and block thermostats so I know they are good, but I guess I could pull them and try your troubleshooting method. There is a pressure release valve (looks like a thermostat) in that same general area of the motor that I have not changed yet because I need a special wrench to get into that tight space. Considering the way the thermostats looked and the sand that clogged the flush valve itself, I’m thinking that pressure release valve needs to be changed as well.

 

[Dcav66]

The flush port valve and first nipple are on the right in green - they are good and clean now and water flows when I hook up the hose to it. However, the nipple on the left in red going back into the motor has also been cleaned out but no water can pass from there to the pee hole which leads me to believe sand is clogged up in the mount case somewhere,

 

[Sea Rider]

Is this a fresh or saltwater motor use ? Poppet valves are usually a 3 parts component, very simple to remove with the right tool and cleaned soon after, no need to change it unless shot.

When the Owner's Manual says to flush through the flushing port installed with motor OFF will need to count with a water hose that delivers high water pressure to open up the thermostat. Try both methods. Sand usually will not clog anything inside the motor, salt layers, crusts will if being a salt water motor.

Happy Boating​

 

[Dcav66]

I’m in Florida so I use it for both. I bought it used in June, so not sure how much saltwater it had seen before me. It only had 300 hours on the motor and everything ran and looked good when I bought it, but the motor is a 10 yeas old motor. In any case. I have gone through the motor throughly and replaced all the usual service items. Again I always used muffs to flush it so never thought to use the flush port. So when I tried it, I found this clog issue, When i disassembled the flush valve, it was definitely packed with a fine sand/salt sediment to a point where it wouldn’t pass any water through the valve or out the first nipple with the small jumper hose removed (see picture). After cleaning and reassembling, it now passes water through that first section with ease. I have high water pressure so I know that’s not an issue. I cleaned out the second nipple as best I could, also removing sand/salt sediment. Still no water will pass through that section though. I also tried blowing out with high air pressure and that didn’t work. Next step is I will remove both thermostats to see if i can get water or air to pass.

 

[Sea Rider]

Yep, pure sand should cross through all the water passages and exit out motor, but if being a salt motor use it's a different story. Now imagine how salted already are all the internal water passages..

Happy Boating​

 

[MattFL]

Sand and silt can build up along with salt. If it's used in shallow or silty water a lot, sand can settle out inside the motor and build up over time. How to get it out is another story. Short of disassembling it, maybe try to attach a stiff plastic or rubber hose to the end of a garden hose and ram it up in there while the water is turned on to try to chip it out or spray it out with the water.

 

[Dcav66]

Solution - See the following YouTube video which shows what I did to fix the problem:

 

[Dcav66]

Update: Issue resolved – it turns out there was lots of clogging from scaling and sediment buildup inside the mount case. I ended up using some creative ways to get the mount case unclogged and I flushed the entire motor several times with Rydlyme to clean it up....all good now! Here is a video that describes what I did: