Crankcase Sealer

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marshg246

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I've always used Permatex Aviation Form-A-Gasket #3 for my crankcase halves but I see people here recommending Yamabond, HondaBond, Welseal, and Hylomar.

On Triumphs and BSAs once you bolt the cases together, they are done. With Isolastics, the cases are only partly squeezed tightly together until installed in the bike so I'm wondering if that makes (or should make) a difference in the product you use.
 
Actually best practice regardless of type of goop is let get tacky before assembled then delay full clamp force til fully set up before firmly trapping the semi hardened sealant. All the goop listed should work fine, until trying to separate again, which is main reason I use expensive Hylomar, a type of sillycon, of which there is a handful of grades to try. A light dab on carb screws keeps them put yet not destroy screw slots removing. Don't do that with other sealeants or may have to drill screws out. Oh yeah not a bad idea to use non synthetic thread laid down, cotton or silk, as synthetics melt leaving gaps.
 
Permatex also makes Moto-Seal, a motorcycle specific product that is similar to Yamabond, Hondabond etc.
 
I use Yamabond 4 [or one of the copies like 3 bond]

Assemble it immediately with a full set of bolts. Then remove the dummy bolts where the mounts fit after it has set up overnight. Jim
 
Actually best practice regardless of type of goop is let get tacky before assembled then delay full clamp force til fully set up before firmly trapping the semi hardened sealant. All the goop listed should work fine, until trying to separate again, which is main reason I use expensive Hylomar, a type of sillycon, of which there is a handful of grades to try. A light dab on carb screws keeps them put yet not destroy screw slots removing. Don't do that with other sealeants or may have to drill screws out. Oh yeah not a bad idea to use non synthetic thread laid down, cotton or silk, as synthetics melt leaving gaps.

Not to be excessively anal, but none of the sealants mentioned are silicones, and believe none of them cure, but rather are thermoplastic polymers delivered from solvent that simply air dry to provide the neat polymer and it's accompanying physical properties. Because the sealant does not cure, the dry sealant can be removed by resolvating with the original solvent it was delivered from.

http://hylomar.com/warrick/wp-content/uploads/2013/10/Hylomar-Universal-Blue-Issue-8.pdf

Silicones on the other hand are RTVs (room temperature vulcanizing), i.e., they do physically x-link/cure and can therefore be much more difficult to remove or loosen joints after the fact.
 
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I believe Yamabond and Hondabond are just rebranded versions of Threebond - all very good.
For a non-gasketed joint such as you mention Threebond grey works very well.
Pommy purists will tell you Wellseal...
Fundamental, of course, is preparation of the joint surfaces (flatness, cleanliness)
Cheers
Rob
 
After using silicone for years without any problems, a friend recommended Wellseal so I tried it about three years ago. Last year my crankcases were showing signs of weepage! When I'd assembled the crankcases, I'd left the Wellseal for more than 6 hours to "cure" before assembling and had wiped the crankcase surfaces with Brake cleaner prior to assembly.
Maybe I was unlucky?
I'm back to using silicone on the Norton now.
I have used Loctite 518 on my triumphs before with good results.
 
When I was on the spanners Wellseal was a staple sealant to the degree we had it in spray can for applying to Rolls Royce & Gardner diesel head gaskets etc...It smell awful like dry cleaning solution, sticks to hand & cloths like s*** to a blanket.... and never really stopped them from leaking oil
 
Is the Yamabond / Hondabond / threebond a silicone based product?

I’m a big Wellseal fan (well I am a Pommy) but Wellseal is no good as a ‘gap filler’ so if I have any unevenness, or deep marks, scratches, dents in the surface, I tend to use a silicone product.

I used Wellseal on the primary case on my T120... which now has a very ‘purist’ Triumph oil leak! It’ll get silicone next time.
 
After using silicone for years without any problems, a friend recommended Wellseal so I tried it about three years ago. Last year my crankcases were showing signs of weepage! When I'd assembled the crankcases, I'd left the Wellseal for more than 6 hours to "cure" before assembling and had wiped the crankcase surfaces with Brake cleaner prior to assembly.
Maybe I was unlucky?
I'm back to using silicone on the Norton now.
I have used Loctite 518 on my triumphs before with good results.


The problem was letting the Wellseal set before assembly. Solvent based sealants should be assembled immediately.

RTV [silicone] works ok if your very careful that excess does not hang out in the case where it can come loose and plug oil passages. Jim
 
I believe Yamabond and Hondabond are just rebranded versions of Threebond - all very good.
For a non-gasketed joint such as you mention Threebond grey works very well.
Pommy purists will tell you Wellseal...
Fundamental, of course, is preparation of the joint surfaces (flatness, cleanliness)
Cheers
Rob

Rob,
That's interesting. I just did a quick Google search. Turns out that ThreeBond makes a large assortment of sealing products. I believe the "grey" you refer to is TB1215. See

https://www.techsil.co.uk/media/pdf/TDS/TBSI19040-tds.pdf

When I Google "YamaBond TB1215 4 - MC tech data sheet" or ThreeBond TB1215 tech data sheet" I get the result linked above. The MSDS for YamaBond TB1215-4-MC lists ThreeBond as the distributor. See

Removed broken link

According to the document linked above, this stuff has Calcium Carbonate as it's leading ingredient, not silicone.

I could not find any info regarding the ingredients of WellSeal. That said, by it's description, it appears [to me] to be a different product than ThreeBond TB1215 or YamaBond TB1215 4 - MC
 
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Actually best practice regardless of type of goop is let get tacky before assembled then delay full clamp force til fully set up before firmly trapping the semi hardened sealant. snipped

Both ThreeBond & Locktite 518 recommend immediate assembly of the parts. ThreeBond allows up to 30 minutes delay. No one recommends letting this stuff fully setting up, before applying full clamping force. See

https://www.techsil.co.uk/media/pdf/TDS/TBSI19040-tds.pdf

On the link below, refer to page 3, right hand column for use instructions

https://tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/AACE3993B0D66F88882571870000D7DE/$File/518-EN.pdf

I use Hylomar on overhead camshaft engines when installing the front camshaft bearing caps. These caps retain the camshaft oil seals. They also have drilled oil passages that must not be blocked by a sealant which "sets up" like YamaBond, as the sealant could plug the oil passageway. Sealant must be used here, to prevent an oil leak which could be mistaken for a bad camshaft oil seal.
I've always found it best to install & torque down these caps as soon as is practical. Otherwise, you may get "shimming" as warned about in the Loctite 518 directions. That would require a re-torquing of the bolts.
 
OK following instructions on sealants is generally good practice. Some don't need any time to get tacky before slapping together but even the immediate contact types still benefit to delay final clamping (if practical) to try to trap a decent layer in between w/o mooshing as much out, especially in distorting/shifting Norton seams.

My least favorite is the dark tarry syrups as don't fill gaps as well, too hard to part like glue later and have seen it heat harden to fracture tiny cracks oil weeps out. Forum activity often runs on Norton innate sealing issues.

Acertel My wife has pointed out to me various spray on exterior sealants for hoses and tubs and roofs and boats. I sure thought about to mask off over spray and touch up with grey paint.
 
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If a piece of the silicone type gasket sealer breaks off it could clog an oil passage or even the pump. I know that Hylomar states it will break down in oil and not cause a clog. I also believe the “-Bonds” behave the same. Hylomar will separate pretty easy on a sealed surface because it never really “hardens”, I think the “-Bonds” set up more when cured.
Pete
 
Oil and water and heat tend to break down silicons goops quicker that other types, not the silicon but the binder to find pieces inside oil filter especially after break in filter inspection. All experienced and investigative boat owners never use RTV below water line. Hylomar excess can break loose too but does tend to stay in seam or just have a strip of Hylomar with one end still adhering. RTV is definitely not long lasting where Norton are prone to leak. Hylomar is pricey and stickier than RTV's so my only Norton use of RTV is slight smear on small fasteners instead of over tough loctites or risk mangling slots and my self opinion failing to remove. Carb and switch gear, fender and chain gaurd, tail light mounts.

Alas Hylomar ain't all that much better than alternatives, especially if enjoying on cam performance, so I put cotton/silk thread in cylinder case which don't melt like snythetic threads do. Ugh, also found out about keeping up with initial frequent enough re-torques, as once crush slack allows a weep, about impossible to re-torque enough to stop in reappearing.

Hylomar is one the trickest to get evenly spread and just collects on finger spreading, unless licked/wet. I settled on thin short/stiff detail artist brush to push it around more than brush on.

When I ran Peel like a racer all the time I found the toothpaste/calcium carbonate types to act like corn starch/water mix, the harder its compacted and shocked the stiffer it gets to point can fracture paths through it but still stick like glue, ugh.
 
I have used hylomar on the cases of 2 motors , both are leak free , very happy.
 
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