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BF225 exhaust guide seals replacement necessary?

You don't have to have electrolysis to eat away at aluminum. Cavitation causes air bubbles to come out of the water in areas with with turbulence. If you look at the area where the thermostats go into, it appears that there is a larger "open chamber" (where you have the very bad corrosion) with a restriction below, and restriction above (the actual thermostat). I think there is a problem with cavitation in that area that is aggreviating the problem. Owners of early ford power stroke diesels had the same issue with the heads corroding from the inside do to caviation in the cooling passages within the heads. The solution was a special additive and higher pressure radiator cap to keep the bubbles from coming out of solution around that certain part of the cyl heads cooling passage. This eleminated the cavitation issue, and owners stopped having problems. I think adding a liner inside this passage and epoxying up the area around the liner with JB weld would be a good solution for your problems. Use a stainless steel wire brush to clean out all the existing corrosion. you want bright shinny alum to bond the epoxy to. If necessary, use some "the works toilet bowl cleaner" to clean up the corrosion (works wonders on pontoon hulls as well :) ) it's a mild acid that removes the scale and corrosion but does not damage the underlying aluminum. Then find you a sleeve that will fit inside the area and around the thermostat. put some paper towels down in the water passages, then fit a piece of foam, or styrofoam board down at the bottom of the cavity. You want the sleeve to dig into this piece of foam so the epoxy won't leak past the outside of the sleeve. Then once the epoxy is hardened, you can dig out the foam and paper towels. If you have a water pressure gauge installed, then you will need to drill and tap the epoxy & sleeve to accept the barb for the water pressure gauge.
 
If I did the job again, I would just inspect the seals, remove all the old grey silicone, and re-silicone with permatex ultra copper. Try to keep the old silicone from falling into the ports, as it will clog your tell-tale over and over again. Not a big deal, but annoying.
As a side note, i've been running hard without the midshaft bushings for 2 seasons with no issues.
The JB weld in the thermostat cavities was deteriorated when I replaced the thermostats last spring. This time I cleaned the area's up again, and coated with POR-15. Also started flushing with salt away, and late season I began tilting my engines towards the starboard side rather than port while docked, since only the port side thermostat cavities were corroded. I figure maybe that was part of the issue, and let the starboard side take the beating for the next ten years. I try to position them strait up and down, but the steering eventually lets them settle one way or the other. I will post my results some time in May
Lastly I have a leak in one of the power trims where the trim motor bolts to the housing. Bad o-rings I guess. I'm almost glad it's too cold out to work on the thing, but will post details of that job in the spring if anyone is interested
 
If I did the job again, I would just inspect the seals, remove all the old grey silicone, and re-silicone with permatex ultra copper. Try to keep the old silicone from falling into the ports, as it will clog your tell-tale over and over again. Not a big deal, but annoying.
As a side note, i've been running hard without the midshaft bushings for 2 seasons with no issues.
The JB weld in the thermostat cavities was deteriorated when I replaced the thermostats last spring. This time I cleaned the area's up again, and coated with POR-15. Also started flushing with salt away, and late season I began tilting my engines towards the starboard side rather than port while docked, since only the port side thermostat cavities were corroded. I figure maybe that was part of the issue, and let the starboard side take the beating for the next ten years. I try to position them strait up and down, but the steering eventually lets them settle one way or the other. I will post my results some time in May
Lastly I have a leak in one of the power trims where the trim motor bolts to the housing. Bad o-rings I guess. I'm almost glad it's too cold out to work on the thing, but will post details of that job in the spring if anyone is interested

Thanks for the quick response Jamey. I have a leak coming from the bottom of the right side exhaust cover. My plan is to pull the cover and replace that O-ring I see on the chart. According to the manual, for removal, its pretty straightforward and the cover lifts straight out, not even really effecting the exhaust guide I dont think?? However upon installation, the manual says to remove the extension case as well.

My question is, will the top exhaust guide seal be able to be removed with the exhaust cover removed, or does the exhaust guide housing have to come off as well?
 
Are you referring to the manifold as the exhaust cover? If so, yes, you simply remove the manifold and replace the manifold gasket and o-ring, #3 and #20 in the first diagram, and then #2 in the second diagram. The extension case and exhaust guide does not have to be removed to replace the top exhaust guide seal, #2.
Are you leaking water down there, or exhaust?

 
Yes the exhaust cover. Here is a video I took that shows exactly what I am talking about. I was hoping to get a new exhaust cover gasket #3 and the O-ring #20 to fix it. It doesnt appear that it is leaking down by where the seal (#2) sits. You can see where water leaks in my video, it literally drips down where my finger is pointing.

http://s.photobucket.com/user/BigNi...1-408F-861B-A1BD2B9F70A0_zpsxkbg4qkn.mp4.html

Also when you used the permatex, did you simply put a bead where the two metals meet or did you do this without getting any on the seal?
 
Ok, looks like the o-ring #20 is most likely your culprit. The seal #2 keeps the water from entering the exhaust, and exhaust from entering the water gasket, so it wouldn't leak water externally if it was bad. Just take a good look at it while you have it apart. As far as the permatex, it is applied in the area where the #2 seal is. Just don't get any where the seal seats against the manifold, and don't put any on your new o-ring #20. When you take it apart, you will see where the silcone belongs. Scrape out the gray stuff, and replace with ultra copper, atleast that's what I did on all four of my manifolds, and it has been fine.
You may want to consider replacing your internal Anodes and retaining screws while you have it apart
 
In this picture, I marked the area with a red line where the silicone goes. Just try not to get any on the lip of the seal
 
Pictures are great. Thank you for taking the time to make it clear for me. Going to stop by the dealer tomorrow for parts and plan to attack on Tuesday and get it done. Thanks
 
If I did the job again, I would just inspect the seals, remove all the old grey silicone, and re-silicone with permatex ultra copper. Try to keep the old silicone from falling into the ports, as it will clog your tell-tale over and over again. Not a big deal, but annoying.
As a side note, i've been running hard without the midshaft bushings for 2 seasons with no issues.
The JB weld in the thermostat cavities was deteriorated when I replaced the thermostats last spring. This time I cleaned the area's up again, and coated with POR-15. Also started flushing with salt away, and late season I began tilting my engines towards the starboard side rather than port while docked, since only the port side thermostat cavities were corroded. I figure maybe that was part of the issue, and let the starboard side take the beating for the next ten years. I try to position them strait up and down, but the steering eventually lets them settle one way or the other. I will post my results some time in May
Lastly I have a leak in one of the power trims where the trim motor bolts to the housing. Bad o-rings I guess. I'm almost glad it's too cold out to work on the thing, but will post details of that job in the spring if anyone is interested



Thanks for side note working mid shaft bushings in am might gamble and leave if too much issue getting back in
 
FWIW, I have about 100 hours on my second patch of the corroded T-stat area on my '02 BF225. First patch was Marine Tex, lasted about 30 hours, this time I used JB SteelStik. Seems to work better.
 
You know what is very interesting. Absolutely no Honda dealers in South florida carry the gasket for the exhaust cover manifold. The manual states DO NOT RE-USE. The little O-ring suspected to be my problem seems available, but not the gasket for the cover.

Exhaust manifold cover gasket - 18115-ZY3-003

O-ring - 91301-ZY3-003
 
UPDATE: I had a hard time getting that exhaust guide seal to seat correctly/evenly down in there. But I did the best I could, and used a bit of permatex inside that area you told me. I'm going to be patient and let the permatex dry for a few hours before starting the engine.
 
In this picture, I marked the area with a red line where the silicone goes. Just try not to get any on the lip of the seal
Can anyone Advise me on the part # for the BF255 exhaust manifold seals for a 2006 model shown in the photo by Jamie. I need to order these ASAP. Any help would be appreciated, thanks
 
jamey,


I was just reading your post and noticed one thing. Since i own a 1/4" plate aluminum work boat I know never ever let copper touch the boat. You said you used permatex copper on your block. Not saying it's wrong but it made me do a double take and write you this.
 
You can look it up for the specific year 2006 on www.boats.net.

Thanks chawk_man. I appreciate your reply.

I have looked the part number up on boats.net; there is a big difference in the diagrams and from 2005 to 2006. Possibly the 2006 was the first year that included the upgrade in SB #56, not sure depending on SN?

The pictures of the seals posted on this thread look very clean compared to mine, they were nasty and came apart when I pulled off the Ex manifold. For those that have corrosion problems, IMHO I don't believe you should re-use the seal and hopefully this can be an addition to the post by BigNiner19 that listed the Ex manifold gasket and O-ring numbers shown below.

The part number for the seal is 18148-zy3-003

Exhaust manifold cover gasket - 18115-ZY3-003

O-ring - 91301-ZY3-003

I appreciate everyone’s input, great information on this forum. It saves a tremendous amount of time Sourcing part#'s.
It's a real pita having to re-order if by chance you get the wrong part, not to mention the time involved with the boat sitting idle...No fun

Thank you!
 
jamey,


I was just reading your post and noticed one thing. Since i own a 1/4" plate aluminum work boat I know never ever let copper touch the boat. You said you used permatex copper on your block. Not saying it's wrong but it made me do a double take and write you this.

Ultra Copper is permatex's high temperature silicone. I'm not exactly sure of what it consists of, but I would be surprised if it broke down and caused any kind of disimilar metal corrosion issues, since it drys like any other silicone. It may just be the color, like Ultra Grey, Ultra Black, Ultra Blue, ETC. I have used it on automotive headers and manifolds with a very good success rate.
HOWEVER, you should do your own research on it first.
Also wanted to mention, that Permatex Grey may be an alternative. Not sure of it's heat properties, but when it drys, it seams to be the strongest silicone in permatex's line. The silicone that I scraped out of there was grey, so it may have been the same stuff
 
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