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2004 BF225 Extension case rubber question (and a few others)

S

Scubagrog

Contributing Member
I went to change my oil in the lower unit of my 2004 BF225 (purchased used 2 years ago) and it had water in the case with the oil. It turns out the gear case has severely corroded, and the wall of the shift shaft is where it is leaking. The wall was actually missing in about 3 spots and you could see the o-ring. So, I'm replacing the gear case. In the process of removing the gear case 2 of the 6 bolts broke off in the extension case and I have not been able to get them out (broke 3 different extractors in the process, yay!). I was curious at how much would need to be done to take the extension case off to get a better angle to work on it and when I removed the plastic outer covers, there is severe corrosion on it as well. The lower mount housings were eaten through in several places and the extension case itself is pitted pretty badly, so I'm planning to replace it as well (probably used that isn't showing much corrosion). After reviewing the service manual and searching through the forum here, I still can't figure out a couple of things. I really don't want to have to take the extension case off to figure it out until I'm actually ready to replace it with the parts in hand.

1) Where does the "Extension Case Rubber" as it is called in the manual (in mine it's on page 12-88, snip posted below) actually go? In a picture on next page of the manual, it shows this nesting in a groove, however in looking at several photos of the part, it doesn't appear to have a groove where it would sit on the top of the unit and in the parts diagram, it doesn't look like it the seal is large enough to fit around the top of the extension. All diagrams I can find show it hovering over the extension case between it and the mount case.

1745725474283.png


Is it actually this?
Extension_case_rubber.jpg

In a picture on the next page of the service manual, it points to this location and says to "apply adhesive between the right 3rd knock and left 3rd knock on the backside of the motor"

2) in the instructions, it says to use ThreeBond 1530C to install this. I can't seem to find any of it. Anyone know of an equivalent?

3) I've seen several folks talking about SB#56 and replacing the exhaust pipes. I have no way of knowing if this was actually done, but was thinking while I have all this stuff off, it might be a good idea to drop the oil pan and replace that stuff as well. Does anyone have a copy of it? I can't seem to actually locate it on the forum.

Thanks in advance for any answers.
 
Hi, before you go threw all the work your planning. My advise is see if you can remove the thermostat and the exhaust manifold to get a good view of the side of the heads. If the engine was not flushed properly, you have more problems then you think. Note I have removed the heads on these engines and found the water jackets on the block ALL PITTED and some have gone threw the piston wall. Because they have not been flushed enough.
 
nocatch said:
Hi, before you go threw all the work your planning. My advise is see if you can remove the thermostat and the exhaust manifold to get a good view of the side of the heads. If the engine was not flushed properly, you have more problems then you think. Note I have removed the heads on these engines and found the water jackets on the block ALL PITTED and some have gone threw the piston wall. Because they have not been flushed enough.
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Thanks for the heads up. The manual mentions to replace the orings at the bottom of the manifold. Is that always done in "real-world" practice? Do the anodes in there normally get eaten up pretty bad?
 
As for the O ring some times it can be reused if it has not been stretched. Now as for the anodes it will vary depending if the person that does the work. Must clean the surface very well and you have to check with an Ohm meter to verify it's making good contact. otherwise the anode will not do it's job.
 
Ok took all the plastic covers off tonight and think I got some answers. There doesn't seem to be anything between the extension case and the mount case and the thing that I was pointing to in the photo seems to be it. The groove looks just like the pics in the manual. I also noted I highlighted the oil drain rubber (6) and not the extension case rubber (7).
 
I just put mine back together.i had to replace a part called “ cover mount case”. The extension case rubber has more of a ledge than a groove. Look at your new rubber closely. Look for the seam where it is bonded together. Pinch this area together before you try to stretch it over the case if you don’t it will break at the seam… I found out the hard way. As far as adhesive I used 3m 4200. It worked fine. The exhaust manifolds are easy . I replaced the annodes. Cheap and easy. I would replace the “o” rings no matter what . You are talking pennies, why not replace them. When I do a rebuild I replace all consumable items. I hope this helps. People on here have helped me tremendously. I try to pay it forward. Best to you,
G
 
Also SB 56. I call a local Honda service center and gave them my serial # and they told me there were no records of it being done, unless it was done outside of a service center. Sure enough mine wasn’t. So I added it to the list . I can tell you start to finish I had about 20 hours. But I’m happy I did knowing now I have peace of mind.
G
 
Garygin said:
I just put mine back together.i had to replace a part called “ cover mount case”. The extension case rubber has more of a ledge than a groove. Look at your new rubber closely. Look for the seam where it is bonded together. Pinch this area together before you try to stretch it over the case if you don’t it will break at the seam… I found out the hard way. As far as adhesive I used 3m 4200. It worked fine. The exhaust manifolds are easy . I replaced the annodes. Cheap and easy. I would replace the “o” rings no matter what . You are talking pennies, why not replace them. When I do a rebuild I replace all consumable items. I hope this helps. People on here have helped me tremendously. I try to pay it forward. Best to you,
G
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I got them off today and already had the orings and anodes on order (had a few misc things that I needed to get, so I threw them in). Today after taking the manifolds off, I also added new seals down near the orings Looked like they were on pieces to the order. As for the ECR I actually think the used case I'm getting already has it on there. I'll see what kind of shape it's in (my current one actually didn't have one on it). I saw what you're saying about the ledge. Around most of it. It seemed to have just the ledge, it was just at the area between what they called the "third knocks" in the manual.
 
I’m replacing my extension casing bc the bushing blow a hole it in side of it. I bought the casing on eBay. Will I need to take the power head off?
 
22cchonda200 said:
I’m replacing my extension casing bc the bushing blow a hole it in side of it. I bought the casing on eBay. Will I need to take the power head off?
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I did not when I did mine. I do suggest trying to support it somehow before you disconnect the bottom bracket. I didn't support mine and although I can't say for sure, but I think it damaged my hydraulic steering cylinder from leaning down too far. It may have needed it anyway, but if I had to do it again, I'd support it somehow.
 
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