Permatex Anaerobic Sealer – The Pro Secret For Leak-Free Engine
Permatex anaerobic sealer is a specialized liquid gasket material that cures only when trapped between two metal surfaces in the absence of air. It is the ideal choice for creating high-strength, leak-proof seals on rigid, machined parts like engine cases, gearboxes, and water pump housings.
If you have ever spent hours rebuilding an engine or a transmission, only to find a stubborn oil weep the moment you turn the key, you know the frustration of a failed gasket. Traditional paper or cork gaskets often compress unevenly or degrade over time, leaving you right back where you started with a messy garage floor and an unreliable machine.
I want to save you from that headache by introducing you to the most reliable tool in my shop cabinet. Using the right chemical sealant can turn a mediocre repair into a professional-grade assembly that lasts for years. By mastering how to use this specific type of sealant, you ensure that your metal-to-metal joints remain perfectly sealed against high pressure and heat.
In this guide, I will break down exactly how this material functions, when you should choose it over a traditional gasket, and how to apply it for a factory-perfect result. Let’s dive into the mechanics of achieving a permanent, worry-free seal on your next project.
Understanding How Permatex Anaerobic Sealer Works
Most people are used to silicone-based RTV (Room Temperature Vulcanizing) sealants that cure when they touch the air. This product is fundamentally different because it is anaerobic, meaning it stays liquid as long as it is exposed to oxygen.
When you sandwich this material between two rigid, close-fitting metal flanges, the oxygen supply is cut off. This chemical reaction causes the liquid to harden into a tough, solvent-resistant plastic film that fills every microscopic imperfection in the metal surface.
Because it does not cure until you bolt the parts together, you get an unlimited working time to position your components perfectly. You never have to rush to beat a “skinning over” time like you do with messy silicone tubes.
When to Use Permatex Anaerobic Sealer on Your Projects
This product is not a “cure-all” for every gap in your workshop. It is specifically engineered for rigid, machined surfaces that require a metal-to-metal contact point.
You should reach for this material when working on:
- Two-piece engine crankcases where no physical gasket is specified.
- Water pump housings that bolt directly to the engine block.
- Gearbox covers and transmission end plates.
- Heavy-duty industrial pump flanges.
Avoid using it on stamped steel covers, such as cheap oil pans or valve covers that flex easily. These parts require a flexible, thick gasket because the metal moves and warps under heat; a rigid anaerobic seal will crack if the joint flexes too much.
Surface Preparation: The Key to Success
No sealant in the world will save you if the mating surfaces are dirty. Even a thin film of residual oil or a tiny speck of old gasket material will prevent the chemical bond from forming correctly.
Start by scraping off all old gasket material with a plastic scraper to avoid gouging the metal. Once it is clean to the eye, you must use a fast-evaporating solvent like brake cleaner or acetone to remove all microscopic traces of oil.
If the surface feels oily after you wipe it, keep cleaning. I always perform a “finger test” on the flange—if I feel any slickness, I hit it with another round of solvent. A perfectly clean, dry surface is the secret to a leak-free build.
Step-by-Step Application Techniques
When you are ready to apply the sealant, remember that less is often more. You do not need a thick bead; you only need enough to fill the microscopic gaps between the metal faces.
- Apply a thin, continuous bead to one of the two mating surfaces.
- Use a small brush or your finger to spread the sealant into a thin, even film.
- Ensure the bead encircles all bolt holes, as this prevents oil from “wicking” out through the threads.
- Assemble the parts immediately and tighten the fasteners to the manufacturer’s specified torque.
As you tighten the bolts, the excess sealant will squeeze out of the joint. You can simply wipe away the external squeeze-out with a shop rag. Since it won’t cure outside the joint, cleanup is incredibly easy compared to the sticky mess of traditional RTV.
Safety and Material Compatibility
While this material is safe to handle, you should always wear nitrile gloves to keep your skin clean and avoid transferring oils from your hands to the parts. It is also important to work in a well-ventilated area, especially when using solvents for the prep stage.
Always check your shop manual to ensure the sealant is compatible with your specific application. Most high-quality anaerobic products are resistant to oil, water, and glycol, making them perfect for most automotive and machinery uses.
However, never use them in high-temperature exhaust environments or areas where the parts are made of plastic or composite materials. This is strictly a metal-to-metal solution.
Frequently Asked Questions About Permatex Anaerobic Sealer
Can I use this sealant on a gap that is too wide?
No, this product is designed for “line-to-line” fits. If your gap is larger than roughly 0.015 inches, the sealant will not be able to bridge the space effectively, and you will experience a leak.
Do I need to wait for it to dry before starting the engine?
While the product cures fairly quickly once the bolts are torqued, I always recommend waiting at least 24 hours before filling the system with fluid or starting the engine. This ensures the chemical bond reaches its maximum structural strength.
Is it difficult to take the parts apart later?
Not at all. While the seal is strong, it is not a permanent adhesive like threadlocker. You can typically separate the parts by tapping them with a rubber mallet, and the cured film is easily removed with a standard gasket scraper.
Does it replace a paper gasket?
Only if the manufacturer design allows it. If the engine was engineered with a specific thickness of paper or metal shim gasket to maintain proper internal clearances (like bearing end-play), you must use that gasket. Never use sealant to replace a component that serves a structural spacing purpose.
Mastering the use of professional-grade chemical sealants is a hallmark of a serious garage tinkerer. By choosing the right product for the right job, you elevate your work from “good enough” to “built to last.” Keep your surfaces clean, respect the torque specifications, and you will never have to worry about that dreaded oil drip again. Happy building!
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