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Old 12-08-2017, 15:25   #1
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Yanmar SB8 versus repower, versus more space and a larger outboard?

I have posted here before about using my outboard to push an H27 up the ICW (8 hp, same hp as the Yanmar SB8 inside the boat), but now have an issue that is a little more complicated to handle.

This last Thursday, we attempted to install a new oil pan on the Yanmar, as the old one had largely corroded away (PO had a seawater hose leak, for apparently an extended time, and it ate the aluminum pan away on one side to the point of forming a knife edge and very little sealing surface against the block). The problem is that the pan the seller on Ebay sent does not actually match the block on the SB8!! So, now I have two pans, one is almost a mirror match for the other in hole placement, and is slightly larger in internal volume due to slightly wider dimensions!

So.. I have a few options now. I need to either make a flange of some sort to transition from proper to this new pan, I need to locate yet ANOTHER pan (this time one that actually fits!), I need to change out the inboard for another that has a pan and hopefully less rust, I need to leave the engine in place and pull the prop for "saving" (for a time when I can locate another engine), or I need to pull the current Yanmar and use the space for storing things, and possibly install a larger outboard (maybe a 16 to 20 hp with sail extension?).

The current 8 HP outboard is on a outboard mount (reinforced) and is set for sailboats, but still does not like "thin" water and cavitates a bit in wakes and hobbyhorse moments.

My guess is that a new owner would consider the engine to be caput, but I don't know for sure, it ran before I got it, according to everyone I talked with about this engine, but I did have to replace a couple valve springs right off.

Well, can't load the pics, but the spring issue is repaired (replaced them as well as the valves), and the head was otherwise relatively clean once I cleared some minor rust from the outside and the water ports.

The engine did try to fire before I changed out the oil pan, but then I was interrupted and unable to fully bleed the engine for several months, found the new pan, and this was my attempt to get it installed before firing the engine up and potentially flooding the bilge with excess oil when pressure started.

Given I don't have much cash to work with (quite little at the moment, in fact), what would be a reasonable approach to handle this issue? I do want a means to motor if needed for approaching docks and the like or in dead winds, and the steering is currently tiller-based.

The boat is not financially worth installing a brand new engine (she is a 1978 H27 with typical ailments of that vintage), but perhaps could benefit from some sort of increased HP in the outboard if one had a longer shaft yet and kept the prop underwater, or if I was able to delete the weight of this potentially useless Yanmar and the associated 12 gallon fuel cell...??

I don't believe I will locate a buyer wanting to restore her to factory original (there is too much to do for that) so she is really a utility role rather than any sort of collectible at this point.

Constructive ideas??
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Old 13-08-2017, 05:34   #2
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

If I am understanding the issue correctly, you are saying the recently acquired "eBay" pan has the same mounting holes as the old pan but does not fit the crankcase properly due to it being wider and thus does not seal???

If so and given the financial constraints, I would be inclined to either source another pan or make some adapter plate / flange.

And FWIW, in case you aren't aware, the SB8 uses a left hand prop and most other engines use a RH prop.
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Old 13-08-2017, 15:20   #3
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

Both pans have ten bolt holes, but the "new" one is slightly larger, and has a mirrored (approximately) shape opening to the original. They roughly clamshell against one another when the open ends are placed against one another. The "new" pan is also slightly larger than the original in circumference (and diameter).

I have been considering the flange/adaptor plate idea, and have come to an additional thought, though I am unsure how feasible it is. I was thinking that perhaps I could create some sort of very shallow bowl to cap off the pan area, with a line coming off it to an oil reservoir mounted someplace remotely from the new shallow pan itself, and have an electric pump push fresh oil from that secondary reservoir to the defacto oil pan area as the engine ran. I could then install an oil filter (as the engine currently does not actually have one in the traditional sense) and I could additionally gain a little more reserve capacity thus allowing the oil to cool a little more during use. If it caused a viscosity issue, I could change viscosity, but at least I would gain a little insurance in case of some sort of leak with that reserve, and the oil would last a little longer perhaps.

I am unsure how to proceed though. I also thought about making an oil pan, using the original as a guide, then folding sheet metal to replicate the shape correctly and drilling the holes where needed. I would then have to seal it to the engine, but I am unsure if the contact point would distort with heat as the engine warmed up. I am a little beyond my depth on engine heat transfer rates, I am afraid. I could alternatively make one of epoxy and glass, but I am also unsure if that would even hold up at all, so am reluctant to attempt that one. I have the materials, but don't know if that is something that epoxy would withstand.
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Old 13-08-2017, 15:50   #4
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

I'm amazed they used an aluminum pan actually, but how about having a welder weld a plate over the hole on the original pan?
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Old 13-08-2017, 16:52   #5
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

Well, I wish I could list a photo of the original pan here again, but it seems to be about impossible. The original pan had some corrosion on the port side that all but ate entirely through it. That side has thinness of a knife blade at the mating surface, and though the iron block there seems fine, there is not enough pan left at that edge to assure a good seal. The welder would have to create a side thickness, and a bearing surface for the seal, without warping the pan or damaging it farther. I suppose such could be possible, but then we would need to drill holes for the screws on that side again.

It may be possible to do this, thereby utilizing the original "mended" pan again. I also considered using something like JB Weld and making a new side for the pan, then sanding it smooth on the bearing surface, but I am unsure how well it would hold in the long term, or if I would one day need the engine just to have the side (and encased oil) blow out all over the engine compartment at the worst possible moment. I wonder how well JB Weld holds to corroded aluminum that has been soaked and rinsed to remove all the oil and corrosion...?? At least then I could drill the holes out again, and potentially create a good mating surface, with the JB supporting the pan side. I wonder if JW will flake off a hot oil pan (????).

I too am surprised they used aluminum for this pan, and because they did, it corroded away severely when what appears to have been a water hose sprung an unattended leak at some point in the past, and kept what appears to have been constant or near constant contact on the pan side with salt water long enough for it to erode the material.

I am not even sure if this alloy is able to be added to by a welder (as I have never even attempted to weld aluminum before), as it appears to be "grainy" internally (for lack of a better term to describe its internal crystalline structure). It is almost like sintered metal in appearance.

Add to this the cost of welding it (assuming I cannot locate a local welder who would be "nice" to me on this without destroying the pan fully), and I think it may take me again out of reach financially for the repair. I am not even sure the engine runs yet, though I know it tried to turn over before I bled the fuel lines. Now the pan is off, I have to wait until it is fully assembled again to know if it was money invested or good after bad.
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Old 13-08-2017, 16:53   #6
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

The hole on the original is actually a thinning of the side to the point that it eroded through at the sealing surface, and left a knife-blade like thinning of that side, overall.
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Old 13-08-2017, 16:58   #7
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

Still considering you ideas in your post #3 and have been looking for a parts / service manual for the SB8 but no luck yet. Do you have a link for either or the Yanmar part number for the pan?

I'm not familiar with the S series but from the google pics, it look like a cross between the YS series and the GM series - both of which I am familiar with...
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Old 13-08-2017, 18:12   #8
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

I wish I did have a part number, or even a manual. They are danged tough to locate, though I did manage to locate a tractor parts dealer in Texas (USA) that had the valves and valve springs in stock (he was able to provide because they apparently are not different in the tractor versus the marine version of this engine). Still, I have no idea what the part number for the pan is. Searching for it now, though, just in case...
I am also looking for a picture that is online that could show the situation, it would work to help this greatly, I am sure.
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Old 19-08-2017, 11:26   #9
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

Hi all,
have attached service manual, parts breakdown and workshop manual for ysb 8 & 12. mine is 1978 ysb and the "e" "b" and "m" are all very close. hope this helps.
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Old 19-08-2017, 11:31   #10
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

well that didnt work, let me figure this out.
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Old 19-08-2017, 11:32   #11
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

pm me and i will email
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Old 19-08-2017, 11:56   #12
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

Buy bees wax in sheet form.
apply it to the entire outside of the pan.
Layup a new pan with epoxy/glass.
Remove it from the old pan
saw and grind to clean it up.
Drill the attachment holes in the flange.
:>)
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Old 19-08-2017, 21:57   #13
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

Quote:
Originally Posted by Cheechako View Post
Buy bees wax in sheet form.
apply it to the entire outside of the pan.
Layup a new pan with epoxy/glass.
Remove it from the old pan
saw and grind to clean it up.
Drill the attachment holes in the flange.
:>)
The question is then, will the epoxy hold up to the heat and vibration of being bolted against the engine block while it is running? I have the materials otherwise...

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Old 19-08-2017, 22:00   #14
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

If the epoxy won't melt, will resist the deformation differential of the cast block versus the epoxy pan, and will maintain the seal I make with the gasketing material, I will definitely try this. I just was afraid that it would not hold up to use once the engine warmed up...
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Old 20-08-2017, 01:38   #15
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Re: Yanmar SB8 versus repower, versus more space and a larger outboard?

Quote:
Originally Posted by SailingFan View Post
If the epoxy won't melt, will resist the deformation differential of the cast block versus the epoxy pan, and will maintain the seal I make with the gasketing material, I will definitely try this. I just was afraid that it would not hold up to use once the engine warmed up...
Presumably the SB8 is raw water cooled; if so, it's operating temperature will be low. While I'm not sure of it's oil temperature, the cooling water will be about 45 C so I guessing the oil temperature in the pan will be below that.

Most epoxies are good to at least 60 C so it is worthwhile (IMO) to explore this avenue further.
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