701 Rebuild Threebond around Crank seals?

[jpswift1]

I'm rebuilding a 701 for my Superjet and I had a question about putting Threebond (Yamabond) around the crank seals. I put the Threebond between my case halves and then around the crank seals (as I usually do) and after I torqued everything down there was about a 3/4" section between one the PTO crank seal and the case where I didn't see it ooze out like it did around the rest of the mating area of the crank seal/case.

Should I split the cases to make sure that the Threebond is sealed all the way around the crank seal, or was it just maybe not put on as thick as it was in the other areas that did ooze out? Will it still seal alright? I just don't want any air leaks. Any feedback would be appreciated.

 

[john zigler]

Do NOT put case sealer on the seals. Seals go in dry. Adding sealer can cause them to come out actually.

 

[be_lain]

You’re fine as long as you got some in the grooves where the seals sit.

 

[Quinc]

I grease in and between the seals and 3bond the seals and cases. I also let it sit for a few minutes and get tacky before putting them together.

*And dont forget tits out on the seals.

 

[Storbeck]

Do NOT put case sealer on the seals. Seals go in dry. Adding sealer can cause them to come out actually.

I'm interested in why this is. I've always put them in dry other than where the sealer is at the joint in the cases, but not understanding why sealer would cause them to come out.

 

[Quinc]

I'm interested in why this is. I've always put them in dry other than where the sealer is at the joint in the cases, but not understanding why sealer would cause them to come out.

I am thinking it could work as lube and cause them to slide out during install?

 

[john zigler]

I'm interested in why this is. I've always put them in dry other than where the sealer is at the joint in the cases, but not understanding why sealer would cause them to come out.

Case Sealer is slippery, and acts as a lubricant, even AFTER it dries. You should never put sealer on the seals. Seals are designed to go in dry, and do just fine doing so. No need to add sealer....

 

[MADMAT]

From an EXTREMELY reputable builder here on the X.....to me via a message on a 1200 I recently rebuilt.

"If you use case sealer around the outer edges of seals to cases it will help keep them in place. Grease on inside to crank."

So I am little confused here.....because I see other reputable guys commenting otherwise here.

Using sealant makes total sense to me.

 

[WFO Speedracer]

Been there done that on a Yamaha 1100 that the seals kept popping out on, sealer on the cranks seals made the seals pop out easier, it did the opposite of my intention, do no do it.

 

[Storbeck]

Could be it depends on the particular sealer.

I have found that if I put a thin layer of yamabond on gaskets they seem to peal off more cleanly than if they are put on dry, which would be kinda consistent with what John is saying, the sealer actually prevents the gasket from sticking rather than adhering it on. I could also see the sealer preventing the lip in the crank seal from seating properly in the groove in the case, maybe (?). It's not something I ever really paid attention to because I was perfectly happy putting the seals in dry.

 

[Sparkplug]

Go by spec. Or don't. Apparently no one posting just this thread does. Because your all wrong according to the factory yamaha service manual.

The seal should be installed dry. And Yamabond should be used on the case halves. Not "case sealant"

If your gonna do whatever you want. Do whatever you want. But the manual will always be right.

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[Quinc]

On a brand new engine I would do everything dry. But most of these are 20+ years old and warped or nicked etc so better to fill those gaps with a sealer.

 

[Storbeck]

To clarify, I don't know about anybody else but when I say "case sealer" I'm referring to bubble gum, or in a pinch the gooey stuff left over from used duct tape.

 

[Kohldanielzimmer]

 

[Harbor]

Iam in a gen2 Cummins class today and found it uses a sealant applied to outside of seal, it’s called P-80 grip it… 15 minute working time. Reminded me of this thread

 

[Kohldanielzimmer]

@SUPERJET-113 thanks for the manual. Just wanted to point out that the manual does NOT call for using yamabond4 on the cases.

 

[kevbo]

The cases and seals need to be 100% squeaky clean before any sealant can bond to it. I think people are leaving some oil behind causing a lot of seal popping problems. I use sealant and have never lost one but I know many that have so its probably better to install them dry. You can make a seal retainer and bolt it to the case after drilling/tapping a couple of holes.

 

[MADMAT]

The cases and seals need to be 100% squeaky clean before any sealant can bond to it. I think people are leaving some oil behind causing a lot of seal popping problems. I use sealant and have never lost one but I know many that have so its probably better to install them dry. You can make a seal retainer and bolt it to the case after drilling/tapping a couple of holes.

Now that sounds like a great idea! Especially for the 1200 in my jetboat! I may tinker with that idea next time!

 

[smoofers]

Iam in a gen2 Cummins class today and found it uses a sealant applied to outside of seal, it’s called P-80 grip it… 15 minute working time. Reminded me of this thread

P80 makes various water-based assembly style lubricants. What makes most of their products unique is that they dry and no longer lubricate at that point. I've spec'd out their P80 Thix for lubricating O-rings that are in permanent deformation scenarios, where I want the O-ring lubricated for assembly but then stuck tight a few minutes later.

 

[Sparkplug]

Just wanted to clarify the yamaha manual DOES specify a specific gasket maker

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