Thread dope for exhaust fittings? - SailNet Community
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post #1 of 11 Old 08-29-2013 Thread Starter
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Thread dope for exhaust fittings?

Any effective products to put on the threads of mixing elbows and associated bits to make them easier to disassemble for replacement next time? It took me 3 days of Kroil, a torch, and a 4 foot breaker bar to get them apart this time (although the threads looked remarkably good once I got them apart).

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post #2 of 11 Old 08-29-2013
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Re: Thread dope for exhaust fittings?

You can get high temperature anti-seize, however, I might then worry about the bolts backing out and leaking exhaust. Best might be to take them apart more often to inspect and clean.


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post #3 of 11 Old 08-29-2013
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Re: Thread dope for exhaust fittings?

Been using Hercules Rea-Tuff pipe dope for years and years on exhaust fittings.. You can get it at any Home Depot..

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Re: Thread dope for exhaust fittings?

I've used anti seize which seize. Last year i had to use flame to help unscrew the elbow. I use Teflon tape after that. Last week i unscrewed it with just pipe wrench. No struggle. So from now, I'll use Teflon tape. I've no leak with Teflon tape.

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Re: Thread dope for exhaust fittings?

I thought teflon would melt/burn well below exhaust gas temps. Perhaps that heat dissipates a bit by the time it soaks to the bolts. Maybe more on some than other setups. I also thought burning teflon was poisonous.


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Re: Thread dope for exhaust fittings?

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I thought teflon would melt/burn well below exhaust gas temps. Perhaps that heat dissipates a bit by the time it soaks to the bolts. Maybe more on some than other setups. I also thought burning teflon was poisonous.
Don't they use Teflon to coat frying pans?


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Re: Thread dope for exhaust fittings?

"Don't they use Teflon to coat frying pans? "
Yes, and the fine print usually says you will generate phosgene gas and kill someone if you let the Teflon get over 500F. Or gentler words to similar effect.
Ignoring the finer details, Teflon releases nasty gasses when it gets too hot. Which is one reason there are "ceramic" coatings on the better skillets these days, and some of those make Teflon look like junk because they are so much better at not sticking.
Going back to exhaust fittings...I don't think most of the joints would exceed the Teflon critical temperature but I'd verify that before using Teflon there.
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Re: Thread dope for exhaust fittings?

Thought Teflon melts around 600 degs, which would make sense, if manufacturer suggestion is 500. Exhaust gas temps easily exceed 1,000 degs, although, that may not be the temp that reaches the bolts.


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post #9 of 11 Old 08-30-2013
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Re: Thread dope for exhaust fittings?

More information to amuse and confuse:

Exhaust Pipe Thread Sealer - Cruisers & Sailing Forums
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post #10 of 11 Old 08-30-2013
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Re: Thread dope for exhaust fittings?

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Thought Teflon melts around 600 degs, which would make sense, if manufacturer suggestion is 500. Exhaust gas temps easily exceed 1,000 degs, although, that may not be the temp that reaches the bolts.
At 1000 there would be melt-downs of all kinds of components. The temperature of the gas that leaves the cylinder head cools really fast when it gets to the cooling jacket around the manifold.

The water that pours into the manifold jacket will never reach boiling point and by the time it reaches the elbow it is probably not hot enough to make tea.

My exhaust has a glass fibre elbow - I suspect that it would burn through quite a lot earlier than 500 - in fact I would be astonished if it reached even 100C

The mixing elbow has an unfortunate name - it doesn't mix super-hot exhaust gas with cold water. Actually the exhaust gases generally reach the "mixing elbow" heavily laden with water and mostly the elbow is where the excess water that doesn't go to the exhaust manifold jacket is included in the out-flowing mixture. There is no way that it gets hot enough to melt Teflon.

At least that is my experience - YMMV
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