Sealing compound for joining the crankcase halfs

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AZScott

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I am in the process of bolting together the crankcase halfs of a '74 Commando 850. In the past I have used "Hondabond 4" (semi-drying liquid gasket) on Triumphs I have worked on. This has worked well. On the Norton I noticed there are some oil passages near the edges of the case that I will need to make sure the goop doesn't get into. Thought I would ask if anyone has a better compound or special tricks they have picked up to put the halves together.
 
Stick with Hondabond/Yamabond etc. They work well as you have discovered. If you block oil ways it is because you have used too much.
 
I haven't found anything better than Yama/Honda/Three bond for cases. Jim
 
Permatex makes one now called Moto-Seal. Basically the same silicone polymer as all the /bonds but quite a bit less spendy.
 
Danno said:
Permatex makes one now called Moto-Seal. Basically the same silicone polymer as all the /bonds but quite a bit less spendy.
Click to expand...

'Spendy'?
 
Danno said:
Permatex makes one now called Moto-Seal. Basically the same silicone polymer as all the /bonds but quite a bit less spendy.
Click to expand...

I didn't know Yama/Honda/Three bond had any silicone. They are a solvent based sealant.
 
comnoz said:
I haven't found anything better than Yama/Honda/Three bond for cases. Jim
Click to expand...


Yep stick with what works best, my crank cases have never leaked in the 40 years of ownership and have always used Yama bond on all rebuilds and the cases come apart easy when pulled apart.

Ashley
 
comnoz said:
Danno said:
Permatex makes one now called Moto-Seal. Basically the same silicone polymer as all the /bonds but quite a bit less spendy.
Click to expand...

I didn't know Yama/Honda/Three bond had any silicone. They are a solvent based sealant.
Click to expand...

Yes you are correct. Moto-Seal is also solvent based. If you switched labels on the tubes, I doubt any difference could be seen between the Permatex product and the moto-manufacturer's offerings.
 
Danno said:
comnoz said:
Danno said:
Permatex makes one now called Moto-Seal. Basically the same silicone polymer as all the /bonds but quite a bit less spendy.
Click to expand...

I didn't know Yama/Honda/Three bond had any silicone. They are a solvent based sealant.
Click to expand...

Yes you are correct. Moto-Seal is also solvent based. If you switched labels on the tubes, I doubt any difference could be seen between the Permatex product and the moto-manufacturer's offerings.
Click to expand...

Good to know. Last time I needed Yama/Honda/Three bond I ended up ordering it because none of the bike shops in town had any. Permatex may be easier to find. Jim
 
I like the expensive blue snot stuff Rolls Royce developed but what ever you use might consider organic fiber thread laid in the seams as traditional on problematic aircoolled aricraft. Schimdt suggests non waxed floss for instanse.
 
ashman said:
comnoz said:
I haven't found anything better than Yama/Honda/Three bond for cases. Jim
Click to expand...


Yep stick with what works best, my crank cases have never leaked in the 40 years of ownership and have always used Yama bond on all rebuilds and the cases come apart easy when pulled apart.

Ashley
Click to expand...

I use Permatex copper, it's orange in color. A very light smear so its translucent, you can see the aluminum underneath. Do you use hardening or nonhardening Yamabond. I think they make two or three versions.
 
hobot said:
...might consider organic fiber thread laid in the seams as traditional on problematic aircoolled aricraft...
Click to expand...
'Was taught in A&P school to lay #40 silk thread along seam after applying sealant to act as a "crush washer". It works well!
 
ewgoforth said:
ashman said:
comnoz said:
I haven't found anything better than Yama/Honda/Three bond for cases. Jim
Click to expand...


Yep stick with what works best, my crank cases have never leaked in the 40 years of ownership and have always used Yama bond on all rebuilds and the cases come apart easy when pulled apart.

Ashley
Click to expand...

I use Permatex copper, it's orange in color. A very light smear so its translucent, you can see the aluminum underneath. Do you use hardening or nonhardening Yamabond. I think they make two or three versions.
Click to expand...

Non-hardening.
 
Not that is applies to anyone else, but the tar like stuff glues parts together too tough for me to deal with anymore and the grey thick *non hardening* stuff in hi heat hi elastic seam conditions I put Peel through spanking imaginary pissed off sportbikers became work hardened to fracture in place then weep oil so gave up on those over a decade ago thankyou. Putting together a metal roof water cooling spray system and will use blue snot stuff in its threads in case ever want apart again.
 
Yamabond 4, Hondabond 4, and Threebond 1194 are all three pretty much the same sealant, and are pretty much the industry standard for sealing motorcycle crankcases. All three are the same synthetic rubber, semi-drying compound. I've used them for years on Norton and Yamaha crankcases. I also like the Hylomar Blue that hobot mentions. I use it a lot for general purpose mating surface sealing. It's pretty neat stuff, with a long history, starting with Rolls Royce. Google it if interested. I like that it is self-healing. You can remove a cover that was sealed with it, and replace it without cleaning or re-applying the sealant. Lots of other liquid gasket products out there that also work well.

Ken
 
Nater_Potater said:
hobot said:
...might consider organic fiber thread laid in the seams as traditional on problematic aircoolled aricraft...
Click to expand...
'Was taught in A&P school to lay #40 silk thread along seam after applying sealant to act as a "crush washer". It works well!
Click to expand...
i woulda thought this ' #40 silk thread ' type deal would be fairly common here, i'd hafta dig but pretty sure that's what mercedes also does ..at least with some engines that have split (or 2 piece) upper & lower oil pan scenarios
 
Jim you probability can't find the Three Bond etc. in local shops because of the solvents. I remember about 10 years ago the original Yamabond disappeared because the EPA banned it.
 
http://www.aviationpros.com/article/103 ... o-disaster
The latest revision of Textron Lycoming Service Instruction No. 1125 specifies POB No. 4 Perfect Seal and silk thread as the generally used items for sealing crankcase finished parting surfaces that do not employ gaskets. Two other products, RTV-102 or LOCTITE-515 applied as a very thin film without silk thread, may be used as alternate materials for sealing crankcase parting surfaces. Other sealants have not been tested and approved for this purpose, and NONE are approved for other uses in the assembly of Lycoming engines. Improper use of these and other sealing compounds can create serious problems. As an example, a red colored sealant was used by a mechanic to hold the pressure screen gasket in place. As the material solidified, pieces broke loose and eventually blocked the engine's small oil passages causing oil starvation and engine failure. The bottom line: only use those sealant materials approved by the Lycoming Overhaul manual and other service publications, and only use them for approved purposes.
Click to expand...
 
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