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97 Bf15a exhaust leak

T

TreemanMI

New member
So I’ve had this outboard for several years. Every year I swear it has some new issue. After many carb cleanings and rebuild and gremlins in the ignition system I finally got this motor running great last year. This year it had me stumped. Would start up great on muffs and idle as long as you wanted it too. As soon as you put it on the boat and get to the water it would start then die then eventually not start at all like it was flooded. Then removing the cowl (while on the water) while starting it would spew gas from the vent on the carb and not start. I finally narrowed it down to an issue with cowl off/cowl on causing the problem. Cowl off at cold start and it runs like a champ. Cowl on it sputters out every time.

So I took this motor to a Honda marine mechanic … by the way this is the first time I’ve ever taken an outboard I’ve owned to a shop in the 12+ years of owning boat motors. They detected an exhaust gas leak from the exhaust chamber under the power head. They also said that the issue is with the gasket but the kicker is that this part is no longer available?!?!?? You mean to tell me I can’t get a $10 gasket for a ‘97 motor?

part number is 18233-zv4-000

so now what? Can I make a new gasket? Should I just try and seal the leak with something? I’m not against using some JB weld or similar patch if it gets this fixed. I’m just in awe that I can buy parts for my 1962 Johnson without issue but Honda says “screw you” for a much newer motor.
 
Hi,
Sorry you're having trouble.

I looked up the part number for the 15A exhaust pipe from "pre 1997" to 1998. The part number is the same for those year models. 18333-ZV4-610 See item 10 in the link below for pre 1997

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/15hp/bf15ah-las-pre-1997/gasket-kit

And item 10 for the 97 in link below:

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/15hp/bf15am-las-1997/gasket-kit

And item 10 for the 1998:

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/15hp/bf15aw-las-1998/gasket-kit

That gasket failing is the prime cause for the under hood leak that causes stalling on all the older Honda twins. Very common for this to happen at some point.

The gasket is nothing special really and you could easily make one from more robust material if you want to.

I don't recall if you can replace it without removing the power head or by just removing the extension case. I can look that up for you if you don't have the service manual.

Good luck.
 
jgmo said:
Hi,
Sorry you're having trouble.

I looked up the part number for the 15A exhaust pipe from "pre 1997" to 1998. The part number is the same for those year models. 18333-ZV4-610 See item 10 in the link below for pre 1997

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/15hp/bf15ah-las-pre-1997/gasket-kit

And item 10 for the 97 in link below:

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/15hp/bf15am-las-1997/gasket-kit

And item 10 for the 1998:

https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/15hp/bf15aw-las-1998/gasket-kit

That gasket failing is the prime cause for the under hood leak that causes stalling on all the older Honda twins. Very common for this to happen at some point.

The gasket is nothing special really and you could easily make one from more robust material if you want to.

I don't recall if you can replace it without removing the power head or by just removing the extension case. I can look that up for you if you don't have the service manual.

Good luck.
Click to expand...

Thanks so much for the info. I was wondering if someone might know if a different era part would work since I was just going off of the PN the mechanic wrote on the invoice. I guess it’s worth trying

I do have a shop manual for this and it appears that powerhead removal is the only option. I will go that route since it will give me a chance to check out bearings and other stuff that hasn’t been looked at since it was assembled.

Thanks again!
 
Yes! I agree that taking the powerhead off should be seen as an opportunity if for nothing else than swabbing out the oil sump. There's usually quite a bit of sludge in there and getting it out will let that baby's oil run just a tad cooler. The oil filter and it's holder are no longer available so be careful when handling/cleaning them.

I haven't done a 15 but the smaller twins have a "hidden bolt" that you may need to locate.

Take note of all bolt lengths and their locations.

I believe that you will need a new powerhead to sump gasket plus the exhaust gasket at a minimum to go back together.

Best of luck.
 
C6545271-02D9-4CAD-B6CE-87798954FD0A.jpeg
F6650187-AA35-40CB-B286-7FB190425744.jpeg
51BB2E3E-27D0-40F0-9885-C17A9A470594.jpeg
91FCD058-D76F-491C-BF14-46982179A669.jpeg
C6545271-02D9-4CAD-B6CE-87798954FD0A.jpegWell I finally pulled this old girl out of project purgatory…

Got the power head off. Pulled the exhaust pipe and other exhaust components apart. It doesn’t appear to be obvious where this leak is coming from. Can’t see signs on the existing gaskets of leaks on the perimeter. However the seal for the exhaust pipe and water pipe was cracked before I pulled it out…

Anyone know exactly what gasket I should be looking for? The two on the exhaust chamber are no longer available so I would have to make them. Trying to find the others somewhere but no luck yet. It has to be one of these three:

Exhaust manifold gasket
Exhaust chamber gaskets x2
Exhaust pipe/water pipe seal
 
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