Sealant for inlet manifold gasket?

Technical advice Q&A

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ChipChipChipper
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#1 Sealant for inlet manifold gasket?

Post by ChipChipChipper » Fri Aug 02, 2019 8:41 am

I’m replacing the inlet manifold gasket.

The removed one seems to have some kind of sealant on it.

Does anyone have a recommendation of what type of sealant to use?

Should it be used on one or both sides?

This is for a 1970 S2 2+2.

Thanks
Ian
1970 S2 2+2 4.2l

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ChipChipChipper
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#2 Re: Sealant for inlet manifold gasket?

Post by ChipChipChipper » Fri Aug 02, 2019 8:48 am

Soooo after posting this the “similar topics” part came up with much better results than my forum searches (I was too focused on the inlet manifold, not general gaskets).

Recommendations on the forums include:

Blue Hylomar
Aerograde Hylomar
Wellseal
Three Bond 1215

With “Hylomar” being mentioned he most, I assume blue.

Am I correct it should be applied by both sides of the gasket?
Ian
1970 S2 2+2 4.2l

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abowie
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#3 Re: Sealant for inlet manifold gasket?

Post by abowie » Fri Aug 02, 2019 8:53 am

You're trying to stop water going into the inlet of the carbs. The best choice is a silicone sealant.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
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ChipChipChipper
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#4 Re: Sealant for inlet manifold gasket?

Post by ChipChipChipper » Fri Aug 02, 2019 10:04 pm

Thanks for the answer. You really think better than the other sealants?

Couldn’t you also say the same about the head gasket but I’d be surprised if silicone is used there by many people.
Ian
1970 S2 2+2 4.2l

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keithmac
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#5 Re: Sealant for inlet manifold gasket?

Post by keithmac » Sat Aug 03, 2019 1:07 am

Just A thought. My manifold was warped . no gasket or sealant would work . My new engine ingested a liter of coolant. After two tries , I gave up and had a machinist check it . Yup ,warped and pitted. Now machined flat new gasket and sealant called " The right stuff " No problems now.
Regards,
Keith
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1967 S1.25 OTS, 1952 MG TD

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#6 Re: Sealant for inlet manifold gasket?

Post by abowie » Sat Aug 03, 2019 3:25 am

You're looking to prevent coolant entering the induction path. The inlet manifold sees water at radiator temperature and pressure. Silicone is a good sealant for this application. We put a smear of it around all the water passage holes on both sides of the gasket. As Keith says, if your manifold is warped or badly corroded nothing will make it seal.

I agree silicone would not be a good choice for a head gasket. It sees cylinder detonation pressures and temperatures and is torqued down. Silicone wouldn't add anything to this and it is not something you want in your oil passages or combustion chambers.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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PeterCrespin
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#7 Re: Sealant for inlet manifold gasket?

Post by PeterCrespin » Sun Aug 04, 2019 8:36 am

RTV silicone is not fuelproof, ergo use on the intake side is arguable. Hylomar or Hermetite would work for coolant and fuel.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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#8 Re: Sealant for inlet manifold gasket?

Post by abowie » Sun Aug 04, 2019 8:53 am

Everything under the sun can be argued Peter, if you have a mind to. And just about no sealant is fuel proof, as I discovered when I tried to stop my SNGB 3.8 fuel pump from leaking a few years ago.

The water is pressurised and at 90*C. The fuel is a vapour and at below atmospheric pressure or it wouldn't go into the cylinders. Silicone is a good choice. I'm sure that you could use something else. Or nothing. I suspect that it actually doesn't matter that much, but with using silicone our inlet manifolds don't leak coolant enough to make our customers complain.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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ChipChipChipper
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#9 Re: Sealant for inlet manifold gasket?

Post by ChipChipChipper » Sun Aug 04, 2019 12:31 pm

Thanks Keith, Andrew and Peter all very useful. I’ll give her hermetite a go.

Keith - glad you got it sealed. Those sorts of issues can often take a while to do because it’s not such as small job.
Ian
1970 S2 2+2 4.2l

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#10 Re: Sealant for inlet manifold gasket?

Post by abowie » Sun Aug 04, 2019 11:54 pm

I remember the smell of Red Hermetite, but I don't think you can get it any more. If you want a semi-hardening sealant try Loctite 515. We use this on the sump and timing chain cover gaskets. Works well there.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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PeterCrespin
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#11 Re: Sealant for inlet manifold gasket?

Post by PeterCrespin » Tue Aug 06, 2019 9:52 am

abowie wrote:
Sun Aug 04, 2019 8:53 am
Everything under the sun can be argued Peter, if you have a mind to. And just about no sealant is fuel proof, as I discovered when I tried to stop my SNGB 3.8 fuel pump from leaking a few years ago.
I agree Andrew, which is why I only said ‘arguable’. As gasket dressing it’s OK as the fuel should never reach it. It’s different when used on metallic fittings in direct contact with liquid, like fuel banjos or taps etc. In those cases it swells and loses adhesion and if used to seal a damaged surface it will typically starts to weep and/or detach as ‘worms’. Thst’s why there’s always a contraindication on the packaging about RTV and fuel.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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