Topic: Resto Challenge – Salvage These Sandcast Cases? Looking for Suggestions

[markb]

I acquired sandcast engine E1490 several years ago with the intension of repairing damaged cases and getting another sandcast engine back together. Unfortunately, there are six areas that need to be addressed. If it wasn’t for the fact that they’re fairly early, legitimate cases I wouldn’t waste my time. Here’s the number.


And the casting dates.


What happened was the outside bearing on the final driven shaft failed (probably under load) causing the final driven gear to crash into the rear of the crankcase. I understand this wasn’t as common as the chain break problem but it must have happened often enough for Honda to change this bearing on the K2’s.

This caused the crankcase to crack and the bore for the inside final drive shaft bearing to get damaged. Here you can see where the gear hit the inside of the case and the damaged bearing bore.


Here is the crack on the outside.


A closer look.


Fortunately it does not have any chain break damage.


Apparently then, after it was damaged, it must have sat around for a while. Long enough for the oil filter housing mating surface to get corroded. I’ve seen that before on E100.


And a close up.


Then someone finally decided to try to repair it. They should have had someone who knew what they were doing. The stud on the front of the engine between cylinder #3 and the cam chain tunnel is broken off.


Also the stud hole is broke out on the front of the engine on the corner by the #4 cylinder.


Finally it appears that the “mechanic” used a sandpaper disk grinder to remove the cylinder base gasket.


So I have some ideas but I have some questions too.

Should the crack be welded on the inside, outside or both? It would be nice to try to match the surface enough so the repair isn’t very noticeable.

I think the bearing hole can be cleaned out with a boring tool on the mill.

I need to clean up the oil filter housing surface to see how bad the pitting is but I can put that on the mill like I did for E100.

It would just be nice to find an easier way.

The broken stud can be removed by EDM or drilling. The other hole I think will take some welding then re-drilling and tapping and counter boring. Does anyone have the dimensions for the location of the studs? I think someone here made billet cylinders; they would have to have the dimensions.

The sanding damage has me concerned. I need to check how flat it is. It’s much worse than the picture shows. How much material could I skin off the surface without causing a problem? How about smearing some JB Weld on it to fill in the gouges then machining it flat?

Like I said, I think it’s worth the effort and if any of you have any good ideas for some of these repairs I would certainly appreciate hearing them.

[Don R]

 Weld a nut or washer on the broken stud, it might take a few tries but it can be removed.

[754]

Looks like it has a repair in the chain area to me..

[kmb69]

Looks like it has a repair in the chain area to me..

I don't see that. Looks like casting marks to me.

.....
So I have some ideas but I have some questions too.

Should the crack be welded on the inside, outside or both? It would be nice to try to match the surface enough so the repair isn’t very noticeable.

I think the bearing hole can be cleaned out with a boring tool on the mill.
.....
The broken stud can be removed by EDM or drilling. The other hole I think will take some welding then re-drilling and tapping and counter boring. Does anyone have the dimensions for the location of the studs? I think someone here made billet cylinders; they would have to have the dimensions.

The sanding damage has me concerned. I need to check how flat it is. It’s much worse than the picture shows. How much material could I skin off the surface without causing a problem? How about smearing some JB Weld on it to fill in the gouges then machining it flat?

Like I said, I think it’s worth the effort and if any of you have any good ideas for some of these repairs I would certainly appreciate hearing them.

Welding those semi-porous Sandcast cases "nicely" requires significant prep and cleaning. The crap in the casting is bad enough excluding whatever oil, etc has soaked in.

You should be able to mill the base gasket surface just enough to clean up and use a custom thickness base gasket available from Cometic if necessary.

I would be concerned mostly about the output shaft bearing bores. Those need to be precise in both alignment and diameter. Could be tuff depending on their condition.

[HondaMan]

Here's some history about the problem itself, to help the thoughts along: the outer bearing did not receive enough oil in the early cases, and some mods in the gears in front of it helped to toss some more its way. But the biggest failures (in numbers) came from a gadget called the "Tag-a-Long" that appeared big time in 1970. This thing hooked to a trailer hitch ball and provided a front-wheel-grip on the bike(s) so they could be towed behind the family station wagon: these were EVERYWHERE in those days, often towing 750s and British Twins. That was OK for many bikes, except for this one with a dry sump. the bearing then got terribly overheated for lack of any lube at all while being towed many (thousands of) miles, and at the destination the bikes failed after just a short ride. I saw quite a few of these happen. Honda did not understand the cause: they thought maybe the bearing was too small (heck, it will holds nearly 20,000 PSI!), and they changed it late in the "new factory" K2 cases to the double-row bearing instead. Since this one accidentally captured a little bit of oil while running, due to its width, the problems reduced (but not stopped) Honda's warranty claims, which made them happy enough with it.

When the bearing failed, it cocked the shaft, pulling side-loads on the inner smaller bearing. Sometimes this one would hold it for quite a few miles but it, too, would suffer great wear, sometimes rounding the bearing mount surface until the gear hit the case and made loud noises. There are many K3 cases out there with BOTH bearing grooves inside, and they can fit either output shaft.

For the cylinder gasket surface: can you fixture it and run it over a surface grinder? This height is a +/-0.2mm tolerance. The base gasket can be double-stacked, if Hondabond #4 is applied between the 2 gaskets at the holes that drain oil to the crankcase, but contact me for some extra-thick O-rings (2.62 x 10.77 mm) for those 2 oil supply holes in the center rear studs, if you mill this back and double-stack the gaskets. This is similar to the head gasket problem we ALL see today, due to modern head gaskets being too thick (which is ALL of them).

[markb]

Weld a nut or washer on the broken stud, it might take a few tries but it can be removed.

Of course! I've actually done that in similar situations. Don't know why I wasn't thinking of that. That's exactly what I'm after here.

[markb]

Looks like it has a repair in the chain area to me..

I don't see that. Looks like casting marks to me.

I'll clean up that area and post better pics. I really don't think there are repairs in that area.

[ekpent]

 After looking at some of the other stuff you have don Mark if it can be done your the guy who can do it ! 

[markb]

Welding those semi-porous Sandcast cases "nicely" requires significant prep and cleaning. The crap in the casting is bad enough excluding whatever oil, etc has soaked in.

You should be able to mill the base gasket surface just enough to clean up and use a custom thickness base gasket available from Cometic if necessary.

I would be concerned mostly about the output shaft bearing bores. Those need to be precise in both alignment and diameter. Could be tuff depending on their condition.

I've got a pretty good welder who's done case repair. He thinks he can do it. I don't think I have to worry about the strength, more about making sure it won't leak oil.

My company has a machine shop and we have a good machinist. He helped me on that oil filter housing repair on E100. He thinks he can set up to clean up the bores. The main thing is to get it precisely dialed in.

[markb]

For the cylinder gasket surface: can you fixture it and run it over a surface grinder? This height is a +/-0.2mm tolerance. The base gasket can be double-stacked, if Hondabond #4 is applied between the 2 gaskets at the holes that drain oil to the crankcase, but contact me for some extra-thick O-rings (2.62 x 10.77 mm) for those 2 oil supply holes in the center rear studs, if you mill this back and double-stack the gaskets. This is similar to the head gasket problem we ALL see today, due to modern head gaskets being too thick (which is ALL of them).

Yes I think it could be ground or milled. I have access to both. I like the double gasket solution instead of a custom thicker one just in case the engine ever had to come apart it might be missed that there was a thicker than normal gasket. About the thicker o-rings, if the amount that is removed from the surface is exactly the same thickness as the second gasket, wouldn't you just be able to use the normal o-rings? The distance from the bottom of the o-ring to the cylinder base would be the same.

[markb]

After looking at some of the other stuff you have don Mark if it can be done your the guy who can do it ! 

Thanks for the vote of confidence. 

[kmb69]

For the cylinder gasket surface: can you fixture it and run it over a surface grinder? This height is a +/-0.2mm tolerance. The base gasket can be double-stacked, if Hondabond #4 is applied between the 2 gaskets at the holes that drain oil to the crankcase, but contact me for some extra-thick O-rings (2.62 x 10.77 mm) for those 2 oil supply holes in the center rear studs, if you mill this back and double-stack the gaskets. This is similar to the head gasket problem we ALL see today, due to modern head gaskets being too thick (which is ALL of them).

Yes I think it could be ground or milled. I have access to both. I like the double gasket solution instead of a custom thicker one just in case the engine ever had to come apart it might be missed that there was a thicker than normal gasket. About the thicker o-rings, if the amount that is removed from the surface is exactly the same thickness as the second gasket, wouldn't you just be able to use the normal o-rings? The distance from the bottom of the o-ring to the cylinder base would be the same.

MarkB, you are correct as long as you do not change the o-ring counter bore depth and you remove exactly as much material as the thickness of the 2nd gasket. If it does not take much to clean up the surface, I would check the deck height afterword and possibly just use a single base gasket. That would increase the compression slightly and you get a little performance boost.

Sending you a PM.

[754]

 I don't have any cases here to compare chain area.
 There was a portion that looked like weld shadow to me, and it was quite thick in the area about 1.5 inches Down  from the mating surface.
 Hope I am wrong on that.

[calj737]

Weld that crack from inside only and you’ll be fine. A good preheat, 50hz, and a balance of about 68-70 is my preference.

Not sure you have enough of the stud left to weld to, but you could build up an “ear” with MIG squirts, then turn that with a vise grip.

[kmb69]

I don't have any cases here to compare chain area.
 There was a portion that looked like weld shadow to me, and it was quite thick in the area about 1.5 inches Down  from the mating surface.
 Hope I am wrong on that.

Frank, you may be correct. It does look a bit odd the closer I look. Hope you're wrong also.

[754]

The only pic I can find in the factory manual. Some shots are of pre production motors , I think.
Last pic in the tranny section, page 6 in mine.
 However, in one if the pics in first post it shows a rear shot with a number 817 on the case, the sprocket area looks completely ok in that shot.

[PeWe]

Is it really a problem if the case is milled and use std base gasket? It will give a little bit more compression. It must be enough clearance for pistons-head-valves.
Extra thick fiber base gasket will collapse a little and need additional re-torque of head nuts to avoid oil leak, right?

That serial number must have Lotus Root 4-4 pipes

[markb]

I don't have any cases here to compare chain area.
 There was a portion that looked like weld shadow to me, and it was quite thick in the area about 1.5 inches Down  from the mating surface.
 Hope I am wrong on that.

Frank, you may be correct. It does look a bit odd the closer I look. Hope you're wrong also.

I cleaned up the drive sprocket area to get a better look. Yes, Frank might be right.






Any opinions?

[kmb69]

Mark, I would think you could find evidence of welding on the inside and/or surface where the case halves meet if it has been welded.

[754]

If your bearing bores for output shaft have .004 clearance or less. Loctiye will probably hold it.
If the cases go back together, for any reason , i would put a few bolts in the back. Then measure bore with a telescopig guage.  Three ways, if it was welded it may be out of round. If that is the case, The guage will, fit in one area and be loose or tight in the others.

[markb]

Is it really a problem if the case is milled and use std base gasket? It will give a little bit more compression. It must be enough clearance for pistons-head-valves.
Extra thick fiber base gasket will collapse a little and need additional re-torque of head nuts to avoid oil leak, right?

I put a straight edge on the base surface and it is actually pretty flat. There are a few areas where is seems to be rounded on the edges but plenty of surface for a gasket to seal. I'm thinking that it may not be as bad as it looks and I might fill gouges with JB Weld and then mill off a couple of thousandths (after weld repairing the corner hole and removing the broken stud). Then yes, I would use a standard gasket.

That serial number must have Lotus Root 4-4 pipes

Yes, the Lotus Roots were used up to number 4148.

[markb]

Mark, I would think you could find evidence of welding on the inside and/or surface where the case halves meet if it has been welded.

If your bearing bores for output shaft have .004 clearance or less. Loctiye will probably hold it.
If the cases go back together, for any reason , i would put a few bolts in the back. Then measure bore with a telescopig guage.  Three ways, if it was welded it may be out of round. If that is the case, The guage will, fit in one area and be loose or tight in the others.

Two good comments. I will further inspect the cases and put the halves together and measure the hole with a bore gauge. If it was repaired I think it looks pretty good and if everything checks out OK I wouldn't be afraid of using it.

[markb]

I inspected the area opposite the sprocket and I'm not sure what I see. Casting flaws? Cracks welded from the other side? Don't see any evidence on the gasket surface.


Here's a closeup view of wear the gear hit the inside of the case. You can see where the aluminum is smeared. I can't see the crack from the inside at all. I think I'm going to just repair on the outside to make sure I have the crack filled.


I have the case gasket surfaces cleaned up and I'm ready to bolt them together to check the bores. There are a few gouges in the inner bore but it looks like 80-90% is OK. I dressed out the high spots and the bearings seem to seat in well. I'm tempted to just put a shaft with bearings in there and tighten the case around the bearings and see how the shaft turns. No matter what the outer races shouldn't be able to rotate, correct? And either way should I compensate for no gasket sealer by putting shims in? How much, .002" maybe? How thick does that gasket sealer end up when everything is tightened down?

[kmb69]

I inspected the area opposite the sprocket and I'm not sure what I see. Casting flaws? Cracks welded from the other side? Don't see any evidence on the gasket surface.

Here's a closeup view of wear the gear hit the inside of the case. You can see where the aluminum is smeared. I can't see the crack from the inside at all. I think I'm going to just repair on the outside to make sure I have the crack filled.

I have the case gasket surfaces cleaned up and I'm ready to bolt them together to check the bores. There are a few gouges in the inner bore but it looks like 80-90% is OK. I dressed out the high spots and the bearings seem to seat in well. I'm tempted to just put a shaft with bearings in there and tighten the case around the bearings and see how the shaft turns. No matter what the outer races shouldn't be able to rotate, correct? And either way should I compensate for no gasket sealer by putting shims in? How much, .002" maybe? How thick does that gasket sealer end up when everything is tightened down?

That sprocket area just looks mighty strange. If it was a repair, it looks pretty good, especially the case half surfaces.

0.002" is too much. In theory, the sealant fills the voids, and where flat surface meets flat surface it is ultra thin - 0.0001-0.0002" I would guess. I would check them without sealant and only tightened lightly, not torqued to spec. If the output shaft feels pretty solid, I would use Frank's suggestion and put Loctite on both output shaft bearings and assemble. It should run thousands of miles if it is not hammered.

[754]

 It certainly looks good from the inside..
 I remember a guy welding aluminum pipes with oxy acet,  about 40 years back, I think using rod and flux.. much like welding cast iron.. and sometimes foundries would weld up small flaws in castings, to prevent scrapping them.
 I wonder if they ever did that on the sandcast cases, at the factory..