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Honda BF90D fuel spots on water when idling

K

Kidrr

New member
Hello,

I have Honda BF90D outboard 2008 with around 100hour only. Motor is maintained periodically. Did not have any problems with it. Now it also runs fine, pulls very strong, oil pressure seems to be fine as well, oil levels are ok. But I have noticed that when idling some oil or petrol spots start to appear on water. I have checked all the pips, screws, everything seems to be fine. I cannot pinpoint where the fuel comes from, it is not like it is leaking it like hell but small drops appear constantly. I am not sure if those are fuel drops though but they do look like it. Here is a pic:
http://1drv.ms/1n3EV1s

Does anyone know what might be possible causes?

thank you!

K
 
Hi and welcome to the forum.

The first thing i`d suggest is to see it you can get a pole or something through the slick on the water and then smell it to see if it`s oil or petrol. At least that way it`ll give you an idea where to look.

Matt
 
matt.speedtriple said:
Hi and welcome to the forum.

The first thing i`d suggest is to see it you can get a pole or something through the slick on the water and then smell it to see if it`s oil or petrol. At least that way it`ll give you an idea where to look.

Matt
Click to expand...

Thank to Matt for your reply!

I am now going boating so will try to understand if it is oil or fuel. The amount is quite small so it will be difficult. I guess oil floats a bit differently than petrol?
 
Petrol will normally spread wider and you`ll get more of a rainbow effect on the water as it`s thinner than oil. If you can run something through the slick then you`ll soon be able to tell what it is.

Matt
 
matt.speedtriple said:
Petrol will normally spread wider and you`ll get more of a rainbow effect on the water as it`s thinner than oil. If you can run something through the slick then you`ll soon be able to tell what it is.

Matt
Click to expand...

I am now on a boat, the spots are quite small, tried to catch some and smell but it does not smell like oil or petrol or the amount is so small that I can't distinguished the smell. Will take the boat on a trailer after few weeks, will try to investigate on the ground:) checked all the seals everything looks fine. It seems that is comes from cooling system discharge water. Really difficult to pinpoint.
 
chawk_man said:
More likely it is hydraulic fluid from the tilt/trim cylinders. Check your fluid level as soon as possible.
Click to expand...

Thank you for a pointer! need to google how to do it though:) but to be honest tilt mechanism sounder rough a few time, did not think that it is something special. But I wonder why those spots usually start to appear when the engine is idling?

Is there some straight forward way to check hydraulics?

Thanks once more!
 
Pull the boat out of the water. Tilt engine all the way up.Lock in place with the manual lock lever. Check to make sure the hydraulicfluid tank filler cap is tight. Then open up the filler cap and check fluidlevel. If it needs fluid, top it off. Tighten cap. Wipe off all the cylindersso they are very clean. Unlock the manual lock up and move the engine all theway down and up several times and look for leaks around the cylinders andaround the tank. Lock up the engine again and check whether you need to top itoff again. If so, do so, and repeat the process described above. If no leaks,then it is probably something else.

 
chawk_man said:
Pull the boat out of the water. Tilt engine all the way up.Lock in place with the manual lock lever. Check to make sure the hydraulicfluid tank filler cap is tight. Then open up the filler cap and check fluidlevel. If it needs fluid, top it off. Tighten cap. Wipe off all the cylindersso they are very clean. Unlock the manual lock up and move the engine all theway down and up several times and look for leaks around the cylinders andaround the tank. Lock up the engine again and check whether you need to top itoff again. If so, do so, and repeat the process described above. If no leaks,then it is probably something else.

Click to expand...

Hello, still struggling to pin point the reason for the leak. But now I am pretty s sure that it is oil. Engine was trimmed up for a day and when I lowered it into water today small oil stains appeared. I have checked hydraulics and it seems it us nit leaking. The oil seemed to come from a thin space between two parts of the engine cover it is visible on the picture below. I have been checking oil level now regularly and it does not look like it is decreasing. I am clueless Now:)

https://onedrive.live.com/?gologin=1&mkt=en-US#cid=A4F156C4A6A2A5CC&id=A4F156C4A6A2A5CC!8554&v=3
 
You will need to remove the upper cowling to see where it is coming from.

BTW -did you recently change the oil? It is not unusual for some oil to leak down into the upper cowling when the oil filter is changed. Also, it is not unusual for the oil filter seal to leak if not tightened properly.
 
chawk_man said:
You will need to remove the upper cowling to see where it is coming from.

BTW -did you recently change the oil? It is not unusual for some oil to leak down into the upper cowling when the oil filter is changed. Also, it is not unusual for the oil filter seal to leak if not tightened properly.
Click to expand...

Thanks again! Oil was changed before winter. Will continue my hunt for that annoying leak.
 
Not very good start of the season for me. Yesterday went boating, have not noticed oil s spots, so was quite happy:) but as I was going back to marina and floored the engine it went up to 3000 rpms and then rpms increased but the speed did not go up. As if propellers gears slipped. So got pretty scared and thought that the oil could have leaked from gear drive, so was going very slowly with sad face:) and when I was docking switched on reverse and noticed ripped plastic bag floating in water, seems it got caught in propeller. Went to open sea again and engine worked fine on full speed again, what a relief:)

But I wonder could plastic back really cause that behavior? Or should I worry:)

Sorry guys for so many stupid questions!
 
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Pretty much anything caught on the prop will cause the prop to slip against the water. Gotta watch out for those bags, too, they can wrap around the lower unit and cover the water intakes.

-E
 
Also it is possible that your rubber prop hub has become weak and is slipping when something like that plastic bag got involved. Just keep an eye on it and note whether your prop starts slipping at high speed. I make it a practice to always carry a spare prop, thrust washer, castle nut and SS cotter pin on board.

Back your oil leak - you will likely need to remove your lower cowling to find the source of the leak, but first check the bottom of your oil filter.
 
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