Logo

BF75A Water in the oil.

bryyce62

New member
Hello.
I have a '99 or '00 MY Honda BF75A. I bought it in April of 2000. This motor has run flawlessly for 11 years. It had been getting water in the crankcase for a year or so. After repeated attempts to remedy the problem DIY i.e., frequent oil changes, thermostat replacement, I broke down and took it to a Honda mechanic. He indicated that the head or powerhead gasket was the culprit. So I broke down and took it in for gasket(s) replacement.
Gaskets replaced, still getting water in the oil. It went right back to the shop. Still, I'm into this repair already for close to a couple G's. The head is out for a pressure test now. Compression check is ~175 all cyls. Leakdown test did not find any anomalies.

Anybody got any ideas for me? Could this be a cracked block? Has anyone ever seen a cracked block on a BF75A or BF90A? I've looked all over the internet for the last month, and have not found 1 instance of a cracked Honda 75/90 block. This motor has never overheated. What are the chances that I got the only block that ever failed?

If I bought a used BF75A or BF90A that was newer than 2000 (like 2005) would the lower unit from my older one fit on the newer one? I'm thinking that if my block IS shot, I'd rather buy a used complete engine than a rebuilt power head. Maybe have some extra parts for future problems is what I'm thinking.

Thoughts? Comments?
Thanks for your time.

gw
 
Last edited:
It possibly could be a cracked block if you live in an area where it freezes and the motor was tilted up before the water drained...then it freezed. I have not seen a crack block on these either.

Have they pulled the engine or just the head? There are gaskets and seals under the block that could fail and cause water intrusion. This is a very difficult thing to find for sure.

As for using your lower unit on other BF75's. As long as it is truely a 1999 or 2000, it should be compatible with other BF75 or BF90's through 2006.

Mike
 
Please look at the link below for the oil case and oil pan parts blow up for your motor. If this were happening to me, I would highly suspect a problem with item # 5, grommet, water tube or the surrounding mating gasket. While I don't work on these larger engines, I find that they can have similarities with the little twins.

These grommets and the metal that surround them are subject to the high flow of the impeller stream and corrosion. Particularly in salt water operation. The grommet and a very thin gasket are all that is between the oil sump and the cooling system. I be looking at something like that before condemning the engine block.


http://www.boats.net/parts/search/H... BBAL-4200001/MOUNT CASE + OIL PAN/parts.html

Good luck.
 
Thanks to both. :)
Hondadude, the block was never subject to freezing temps. Boat is always garaged when not in use. I live in the Bay Area CA and it never freezes here anyway.
I'm not sure what has been done to the engine. I paid for a power head and cylinder head gasket R&R. The mechanic indicated last Friday that he wants to pressure test the head next. Not exactly sure what that means, but I'm letting him go thru his normal process, since it's a return on a repair that he made.

jgmo, I'll take your idea to the mechanic this afternoon. Thank you

I'll be back,

gw
 
Getting back to update.
Mechanic found a crack in the cyl head. A rather large crack across one of the cam journals extending to one of the head bolt holes.
I guess a new head is in order now, OUCH. I could have done without that.
At least I should be on the water in the next couple of weeks. :cool:
 
Back
Top