Dow 112 Instead of Dow 111?

Anybody have any experience with using Dow 112 paste sealant instead of the 111 type? The reason I ask is because the 112 has higher temp. resistance. Also, the 111 can deteriorate silicone rubber (some aftermarket tubes use silicone seals). I got this info. at Dow-Corning's site, from the product pdf data sheets for each product.

I figured the 112 might be better suited for the return tubes due to their location near the exhaust system? Also, i'm not sure what type of rubber is used in the o-rings for the motor thermostat and intermediate shaft cover seal. The return tube and motor mounted oil cooler seals are green Viton and there should be no problem using 111 with those. 112 might be a little overkill, but what's wrong with a little overkill when you're trying to avoid any future leaks?

Thanks,

Kevin- 87Carrera

Hey, don't crucify me for questioning the recommendations of Bruce Anderson!

I don't have my manuals in front of me so I could be wrong, but are you supposed to be using sealer on these O-rings? I thought they were designed to be installed with just some oil on them. If I'm correct then putting any sort of gunk on them is a very bad idea.

I've heard of all kinds of junk to put on these things. Otto (from Otto's in Venice) recommended Curil T paste. Tried it once and it seems okay. But it gets a little messy- quite sticky stuff. I thought I might try another product for less messy results. Others have mentioned the Dow-Corning stuff. The factory repair manual says to use tire mounting paste. Others have said to use a high temp. grease.

I guess the goal is to keep the seals lubricated but also to keep them from drying out over time. All of the above products are non-hardening, so I guess the idea has some merit?

Kevin- 87Carrera

What is put on the seals is silicon grease, acording to Anderson Dow 111. The workshop manual just says lightly oil. The idea is to allow the O ring to move some to do it's job. You definately don't want to try to "seal" it with some thing that hardens. The compatability issue is interesting you could E mail Anderson to see if he has run in to these issues, he's very good at returning E mails from www.911handbook.com

Curil and other sorts of sealants are usually not to be used in combination with O-rings.
As Warren pointed out already some times, the O-Ring should be lubricated to "seat" correctly in the grove. High temp silicone grease has a beneficial effect as it withstands heat longer time thus allowing the O-ring to re-seat.

Sealants, either if hardening or not, are normally to be used where there is no gasket, or in combination with flat gaskets.
As they prevent the O-ring to re-seat rather than to help it, this is to be avoided.
BUT: if the counterpart is worn, e.g. the grove is damaged, the O-ring cannot properly seal the leak (if lubed or not). In this case, an additional sealant makes sense as a short-term fix. But be aware, that a fluid (or hardening) sealant usually is not capable to withstand higher pressures, so the fix is addicted to leak soon again.

Jens

I don't think the Dow 111, 112 products are a sealant in the traditional meaning. That is, the paste is not necessarily used to prevent passage of the fluid beyond the o-ring. The paste protects the o-ring itself from the fluid it is exposed to. At least that's how I interpret their data sheet. I'm no chemist! Read the sheet and see what you think? I dunno.

Here's the link if you have Adobe to view the pdf format:

http://www.dowcorning.com//fs.pl?filename=data%2Ehtm&path=%5Ccontent%5Chtml%5Cindustries%5Cindustrial%5 Fassembly%5Ctech

Kevin