RTV Silicone Shelf Life

[Legacy777]

I started building my motor this weekend and have run into a possible issue. I used the recommended Subaru sealant, Threebond 1215 (pretty much same thing as Permatex Ultra Grey). However it is not hardening up. I bought the sealant back in 2005 when I built the first motor. It has set inside my house for about five years.

I'm not sure if there's a shelf life for RTV silicone, or if it will harden up with more time. It got a little harder over night, but is still soft. I've got a plate with some blobs sitting outside in the sun to see if heat may help.

I'd hate to pull the short block apart, but I certainly wouldn't want the damn thing to start leaking on me.

Any thoughts or suggestions are welcome.

Thanks

[Legacy777]

Some answers kind of what I figured.....

http://www.ultimatesubaru.org/forum/sho ... p?t=115573

[gijonas]

That sucks ass.its not like splitting the case,cleaning and reassembly torquing is a 5 minute job.

[Legacy777]

It's hardening a little more. I'll probably wait a little bit to see if it hardens up. I'm also probably going to take the rear separator plate off and see how it sealed up. If it sealed ok and dried, that will give me a little more confidence in the sealant.

[gijonas]

The case halves are a pretty precise joint.Im sure it doesn't take much to make a good seal once torqued.

[Legacy777]

I called and talked with an engineer at threebond today. He gave the 12 month shelf life expentancy as well. I decided to bite the bullet and split the halves to redo it for piece of mind.

[AWD_addict]

A tube of sealant is cheap enough to totally justify buying a new one vs having to take the engine apart AFTER finding out it leaks. Good choice!

[Legacy777]

Well....interestingly enough. I went to check things this afternoon. I was going to pull the separator plate off and check how the silicone was. The silcone seems pretty much near its normal hardness. It is very humid down here due to the tropical storm being near by. So the extra moisture in the air may have helped in curing the silicone. I've got a new tube and some gaskets on order. I will likely let it sit throughout the week, and do a test blob of the new tube and the old tube that has sat for the week and see how they compare.

I'll decide at the end of the week whether I'm going to pull apart the whole motor again. Going to call the threebond guys again

[Legacy777]

Called and talked with Threebond again.....this guy said they've done tests, and after about 2 years the properties of the silicone drop off a cliff so-to-say. I pulled the motor apart yesterday and there was definitely spots where the silicone had not cured. For the most part most of it had cured, but who's to say whether it would have had all the same properties as new, including the oil resistance. I'd rather redo it now than later.....just another 20 hrs worth of work....10 to disassemble and clean....10 or so to reassemble.

[gijonas]

Weak,engine building lessons are like STD lessons.

[evolutionmovement]

I think this kind of thing confirms for me why I'm liking working on bikes more.

[Legacy777]

Yeah.....I don't need any more practice....