Author Topic: Loctite 5990  (Read 589 times)

Offline Grunt

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Loctite 5990
« on: May 04, 2018, 01:38:29 AM »
Has anyone used Loctite 5990 for sealing Triumph push in exhausts, or had any experience of using it. Is there a better product? There are a few gas fire flue sealing silicone type products which may work. These days there must be something better than Gun Gum which is what I used 20 odd years ago, and only seemed to last a week or so before the exhaust was rattling around in the head causing backfires loud enough to wake the dead.

Offline R

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Re: Loctite 5990
« Reply #1 on: May 04, 2018, 05:50:07 AM »
Nope, never heard of it.

But doing a search, found this
Loctite 5990 Premium Silicone Copper Gasket Sealant
Temperature Range: -60C to 350C

Which doesn't sound high enough temp resistance to last ?

What about muffler putty ?
https://ssli.ebayimg.com/images/g/-M0AAOSwANpa4mP5/s-l640.jpg
This stuff dries to rock hard, although whether it would survive any vibration or attempted movement of the pipes is a good question.
I've used it very succesfully on pipe-to-muffler joints, where they weren't a good fit.



Offline Grunt

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Re: Loctite 5990
« Reply #2 on: May 04, 2018, 07:59:17 AM »
Quote
This stuff dries to rock hard, although whether it would survive any vibration or attempted movement of the pipes is a good question

That was the trouble with Gun Gum it dried hard cracked and fell out. Iíd never heard of the Locktite stuff either. TMS sell it as an exhaust sealant but I too am dubious about its working temperature. I was going to go with gas fire flue sealant but it seems its for close fitting parts and isnít suitable for wider joints.

Offline murdo

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Re: Loctite 5990
« Reply #3 on: May 04, 2018, 08:25:11 AM »
Loctite 5920 is good for 700deg F and will fill up to 6mm gaps.
https://www.pegasusautoracing.com/productdetails.asp?RecID=7597

Offline L.A.B.

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Re: Loctite 5990
« Reply #4 on: May 04, 2018, 09:22:01 AM »
I use ordinary clear silicone sealant.
Not even the high-temperature silicone.
L.A.B.

Offline iansoady

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Re: Loctite 5990
« Reply #5 on: May 04, 2018, 10:24:39 AM »
I'm with LAB. Used ordinary silicone for years. Any excess inside gets burnt off but between the pipe and head seems to survive well, and is easy to dismantle.

Gun gum is horrible stuff (or at least was in the 1960s when I tried to use it on Mini exhausts and the like).
Ian
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1982 Moto Guzzi V50

Offline mini-me

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Re: Loctite 5990
« Reply #6 on: May 04, 2018, 12:19:10 PM »
Alternatively do the job properly and expand the pipe?

Pipe expanders are available.

Offline Rex

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Re: Loctite 5990
« Reply #7 on: May 04, 2018, 12:52:49 PM »
But if you want to use some goo of some sort there is some HT stuff specifically for fire-backs flues etc and it comes in the same mastic gun tubes as the other sealants.

Offline Grunt

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Re: Loctite 5990
« Reply #8 on: May 04, 2018, 01:35:03 PM »
Thanks for the replies.

If ordinary silicone is successful then I think Iíll go for a heat resistant flue block type, geocell do one available at toolstation that should do the job.

Though itís an excellent idea expanding the pipe isnít that practical in my case as the exhaust outlets in the head have worn unevenly so the pipes would have to be expanded to suit the hole. And unless the pipes were a fairly snug and tight fit some sort of sealant would still have to be used.

I did consider drilling and tapping holes round the outer edge of the exhaust outlet, so a ring clamped to the pipe could bolt up to the head, I think Unity Equipe sell something similar. However in my opinion the wall thickness on the head isnít substantial enough to allow a thread of a useful size to be tapped in it.

Offline john.k

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Re: Loctite 5990
« Reply #9 on: May 05, 2018, 09:33:31 AM »
I think any sealant would need to remain flexible to cope with the vibration.Just use a type that isnt filled with a meltable filler,in other words,black is probably best,as its carbon filled.Some of the gray colors are mineral fillers too.Two quid a tube is attractive too.