Honda 25 fluid in crankcase oil

[Scott Duff]

Honda BF25A - A mix of fluids appears to be leaking into the crankcase oil. Mechanic indicated water and gear oil in crankcase oil. Twice after 50 hrs heavy use at all speeds/hot weather the oil was very dark, thin, with at least 8 oz. added volume. When checking oil level, it overflowed in quantity at the dipstick. Another mechanic attributed this to "blow-by" past the rings. After running 10hrs on fresh oil at lower speeds there is a tan appearance to the oil and some water at the drain bolt. Operation is very smooth with super easy starts and no skips or hesitations. However, there is a small amount of oil observed on the water's surface for a few minutes after starting. Motor purchased last summer used (I'm 2nd owner). Motor has many hours of trolling in 5yrs.

 

[Reel Appeal]

Re: Honda 25 fluid in crankcase oil

Hi,<br /> From your description it sounds like either a blown head gasket or crack in the water jacket.Oil going tan and milky is synonomous with water entry.I would NOT run this motor anymore until repaired as serious engine damage could occur(seizing/galling etc.)You do NOT want water in the crankcase AT ALL.Water and hot bearings don't get along well.If you want to hold on to that Honda take it to a Honda dealer for service.Get an estimate on repair first.How is gear oil getting into the crankcase!?

 

[hondon]

Re: Honda 25 fluid in crankcase oil

It would be interesting to know the specifics of that techs blowby hypothesis.It is true that these 4 strokes can make a little oil ,but your situation sounds extraordinary and this more often occurs in very cold water.Did they do a cylinder leakdown test and what were the results?Water can enter the oilpan in alot of different ways and once it's there it will take some dilligance to get rid of.Are you moored at a marina or harbor that often has rough water?Do'es this motor get removed from the boat and transported haphazardly right after operation?Do you launch off the beach into the surf?

 

[Scott Duff]

Re: Honda 25 fluid in crankcase oil

Hondon - Interesting response...Are you suggesting water could enter through the exhaust port? One dealer said the same thing and that the motor may be too low, so I checked. On my 15' specialty fiberglass boat...1) lower end of motor is at correct depth at lowest point on transom for long shaft model (page 24 in owner's manual), but the low riding transom puts the anti-ventilation plate 11" below water surface but should be only 4"...2) The exhaust port is only 6 1/2" above water, should be 14".<br /><br />Closer observation while fishing yesterday identified SIX events which routinely contribute to submersion of the exhaust port due to the boat being so low to the water. #1-Trim bar is set at lowest positions to get under low bridge, #2-Backing trailer farther into water than minimum needed and submerging exhaust port, #3-Not tilting up motor when backing down ramps and trailering, #4-Quick stops brings up a rush of water at transom, #5-Anchoring at transom so waves and wakes routinely hit transom (sometimes splashing over), #6-Backtrolling, trolling in heavy chop, and backing up to retrieve snags, anchor. I also wonder how much effect the motor's and my weight have on the amount of water the boat draws? Honda Corp. and dealer have been supportive. Need to determine whether an installation problem or if major repairs are in fact needed.

 

[hondon]

Re: Honda 25 fluid in crankcase oil

Water entering through the exhaust ports is exactly what I'm suggesting,and by the info you have just given me you may have to alter your behavior.I'dd still like to know those leakdown numbers to rule out a leaky head gasket but here go'es.Tilt the motor up while launching and anchoring in a following sea.Most water ingestion problems will occur with the engine not running and therefore no exhaust pressure to keep the water out.That explains the small amount of milky oil in your oilpan.Keep me posted.I'll be happy to give you any further advice but things are fast and furious here so just keep at it .

 

[Scott Duff]

Re: Honda 25 fluid in crankcase oil

Hondon - Your analysis was right on. Experimenting with the suggested motor and boat operating variables over several trips (and subsequent oil changes) confirmed that the water ingestion was indeed occuring while the engine was not running (i.e. not tilting while launching and anchoring in "following seas"). After my last trip and successfully modifying my "behavior" the crankcase oil trip was normal. Raising the trim pin to the highest position also helped raise the exhaust port without negative effects on planing angle. I plan to change the oil at more frequent intervals for awhile and, to be safe, have the system flushed when serviced in the fall. I also will be more careful of my on-the-water "behavior" in the future to avoid recurrences. Thanks again.

 

[Frank Martin]

Re: Honda 25 fluid in crankcase oil

dont overlook the thermostat i belive there is a service buliten on this issue if the thermostat is stuck open or something stuck in it holding it open this will cause delution of oil from gas and water the water in these cases would be from the air in the form of condensation much like a dehumidifyer in your home the gas is from the carbs that will mormaly enrich the fuel when the eng is not up to full operating temp in your original post you mentioned thin oil this usally is from gas not water but with the thermostat prob you will have both and on hot dry days the problem seems to go away . just some thing relitively easy to fix you might want to check

 

[steelespike]

Re: Honda 25 fluid in crankcase oil

Boy its great to see good communication,<br />timely diagnosis,having and reading the manual,<br />and ultimately a solution to the problem.<br /> Way to go guys!