Proper Sealants for Turbo'd Engines

[Rich Euro M5]

I have seen a number of individuals mention using silicon based sealants to prevent leaks. This is the wrong stuff to use, particularly any place it might come in contact with the engine oil. The issue with silicon sealers is they have the potential to introduce microscopic contaminates into the oil which can plug the minute lubrication ports in plain bearing turbos. If this happens, your turbo will be toast in a very short time. I've been there, done that, during my turbo Volvo days. Since that expensive lesson, I haven't used silicon based sealants in any engine, instead I use Hylomar products. Hylomar was originally developed for use in jet turbine engines to prevent leaks of synthetic turbine oils. The downside is finding it, and it's expensive compared to silicon sealants. But it's the best stuff I've found and is all I've used for over a decade. Thought I would pass it along for those that don't know about it. You can find out more at the Hylomar website.

Rich

[cvillebimmer]

Good advice. Per Paul Burke's recommendation, that's what was used to seal my turbo motor.

[bornagain]

good to know.... i didnt use anything i just top up the oil and go... haha but no that is a good tip and maybe funny you say that.....

[Brad D.]

When I build rotaries I use Hylomar exclusively. I began to use it on other stuff and am a believer in it.

[bornagain]

imma have to find me some of that for the next motor i build, which might be sooner then later. After everything this one has gone through, im thinking a spare might be very worth while.

[turbodan]

My entire engine is sealant free. I just use gaskets where required.

[alijonny]

sweet, my local parts store carries it!

[SamSpade]

How does newer stuff like Loctite 518 (Gasket Eliminator Flange Sealant) compare to the Hylomar? Have a tube on hand but haven't used it yet. Looks like a lot of people like it as a substitute or replacement for Hylomar. Easier to find too.

[Scottinva]

That loctite stuff is kickass. My neighbor works on steam equipment for the navy. He said they use it on all the gasket surfaces, wether there is a gasket or not. I used it on my timing covers and have nothing but great results. I don't have any experience with the other product.

[Rich Euro M5]

How does newer stuff like Loctite 518 (Gasket Eliminator Flange Sealant) compare to the Hylomar? Have a tube on hand but haven't used it yet. Looks like a lot of people like it as a substitute or replacement for Hylomar. Easier to find too.

The datasheet for this product indicates it hardens. Hylomar is non-hardening. It also doesn't have the temperature range of Hylomar. I'd use the Loctite product for sealing transmission cases, I wouldn't use it to assemble an engine.

Just my $.02.

Rich

[Scottinva]

Rich is correct about this, the product does harden(loctite). I use it on valve covers, and timing covers, and things like that. I'm not sure i'd use it to seal up an engine. It SOUNDS like this hylomar product would be better for that. It looks like an amazing product, thanks for the heads up. I wouldn't be using it a whole lot at its cost though.

[Jeremy]

Ideally, you shouldn't be sealing an engine very often. I think this sort of product falls in the "do it once, do it right" category.

[SamSpade]

How does newer stuff like Loctite 518 (Gasket Eliminator Flange Sealant) compare to the Hylomar? Have a tube on hand but haven't used it yet. Looks like a lot of people like it as a substitute or replacement for Hylomar. Easier to find too.

The datasheet for this product indicates it hardens. Hylomar is non-hardening. It also doesn't have the temperature range of Hylomar. I'd use the Loctite product for sealing transmission cases, I wouldn't use it to assemble an engine.

Just my $.02.

Rich

I don't see anywhere in the TDS where it says it hardens. All it says is it 'cures'.

From Loctite website:
"Loctite® 518™ Gasket Eliminator® Flange Sealant forms a flexible, solvent-resistant seal that will not tear or decay. Seals to 300°F and fills gaps to 0.50". Can be used on flexible metal assemblies, including aluminum surfaces. Easy disassembly and cleaning."

I also use Three Bond 1104 or 1194, which are popular and easier to find in my part of the world.

I guess we're overthinking all these silicone-replacement gasketing products.

[Scottinva]

It really does harden. I know it does, I have been using it for over a year.

[mooseheadm5]

I use it on valve covers, and timing covers, and things like that. I'm not sure i'd use it to seal up an engine.

I would say using it on valve covers and timing covers is using it to seal up an engine.

[SamSpade]

He probably meant not using it on pressurized flanges like the water (pump, thermostat housing and cover, gooseneck) and oil (filter housing, rear camshaft "duck" cover) systems.

Non-pressurized would be the valve and timing covers, rear crankshaft seal cover, oil pan, and front transmission seal flange.

[mooseheadm5]

It could still be introduced to the oil system, though.

FWIW, I do still use silicone based sealants on select water related components, mostly due to eroded parts not sealing well with gaskets.

[M. Holtmeier]

I used to use 518 a lot on trans cases, diffs, axle flanges and the occasional front gear cover. I was always told it "mixed" with the oil, or would not cure in contact with oil.

[Rich Euro M5]

How does newer stuff like Loctite 518 (Gasket Eliminator Flange Sealant) compare to the Hylomar? Have a tube on hand but haven't used it yet. Looks like a lot of people like it as a substitute or replacement for Hylomar. Easier to find too.

The datasheet for this product indicates it hardens. Hylomar is non-hardening. It also doesn't have the temperature range of Hylomar. I'd use the Loctite product for sealing transmission cases, I wouldn't use it to assemble an engine.

Just my $.02.

Rich

I don't see anywhere in the TDS where it says it hardens. All it says is it 'cures'.

The tip off that it hardens, it's listed as acrylic and there is a hardener. In addition it's capable of gap sealing. Typically acrylic plastics are a form of hard and clear plastic. There's a trademark name for it, it's called Plexiglas.

Rich

[itsbrokeagain]

i used to use the orange loctite stuff when assembling aircooled flat-six engines. It works wonders when assembling the center case (both halves get bolted together and use only this stuff to keep it sealed and keep the oil in.

loctite 574. It dries up and seals in the absence of air...so as long as its exposed to the outside air it will not dry right away...usually takes 12 hrs for it to fully cure inside and out.