Best Gasket Sealers: Keep Fluids and Gases Inside Where They Belong

A preferred gasket sealer used by technicians worldwide, this sealer adheres to any surface, is high tack, and remains flexible after it cures. The sealer works in all sealing and gasket situations, from water pumps to exhaust headers. It’s good for work on cars, SUVs, and trucks, diesel, gas, and electric motors, as well as transmissions and trim.

However, take care not to get the gasket sealer on your hands. Wear flexible gloves when working with it because some users report that the gasket sealer is difficult to remove without using strong chemicals. Also, there have been some reports of the product’s reduced quality compared to earlier years.

This sealer is safe for use around sensors. It is non-corrosive, long-lasting, and adheres well to oily parts. It resists many powertrain liquids like gear lube, engine oil, coolants, and transmission fluid. The sealer is highly flexible and does away with the need for pre-cut or pre-formed cork, rubber, and paper gaskets. It works for oil pan applications and valve, differential, and timing covers. It also maintains sealing abilities from -65 to 500 degrees Fahrenheit. 

However, be careful when dispensing the product. It flows out easily and, therefore, you can easily squeeze out too much and it may end up where you don’t want it, like on the inside of moving components. Some report that it is difficult to clean up.

This gasket sealer from Permatex is slow drying to allow you to assemble your parts. It works well for adhering cork, paper, or rubber gaskets to vertical or horizontal surfaces. It resists grease, gas, and oil. You can use it on multiple aviation and automotive applications such as solid gaskets, on tight-fitting machined surfaces, and for sealing hoses. 

Caution: Use this gasket sealer in a well-ventilated area because the fumes from this sealer are very strong. Keep in mind that it does not work very well for threads on fuel lines. Also, some users report that the bottle may leak.

Permatex has several sealers on the market, and The Right Stuff is geared towards automotive use. It efficiently works on components such as water pumps, oil pans, thermostat housings, and gearbox and valve covers. The product has a continuous temperature range of minus 75 to 450 degrees Fahrenheit with an intermittent range of 500 degrees. The Right Stuff creates an instant, durable, and leakproof seal by creating an elastomeric rubber gasket. The sealer resists blowouts and prevents leaks and seepage due to thermal expansion and vibration. It cures quickly, and it produces a seal that is somewhat soft but tough and solvent-resistant.

One downside with this product is it's very messy, and it can also be challenging to extract from the tube. As a result, you may have to use a regular caulking tube to use it. There have also been some complaints that the nozzle breaks, making it difficult to get access to the sealer.

Many automotive manufacturers and Formula 1 teams use this non-setting and non-hardening gasket sealer. It is designed for sealing gaps up to 0.25 mm and for dressing gaskets and threads. The product is vibration-resistant and can withstand severe changes in temperature. Hylomar Blue is resistant to fluids such as engine coolant, petroleum, lubricating oils, and water. A little bit of Hylomar goes a long way. It creates a leak-proof seal and is one of the best all-purpose, non-hardening gasket sealers on the market. Since it doesn't completely harden, it's ideal when you need to seal a joint that has coolant or oil passing through it. For example, you can use it to seal camshaft caps on overhead cam engines. If you want to keep oil in and everything else out, this is the perfect product.

There are just a couple downsides to this gasket sealer. It may separate over time if you leave it sitting in your toolbox. Also, it's a tough and sticky substance, and if you put it on the gasket and the surface and need to remove it, there's a good chance you will ruin the gasket material.

Designed specifically for automotive engines, this gasket sealer from 3M cures rapidly in place and is flexible and non-corrosive. It can withstand intermittent temperatures up to 600-degrees Fahrenheit, is oxygen sensor safe, and resists water, oil, and ethylene glycol. You can use it as a gasket dressing or gasket alternative. The product comes in a 3-ounce tube.3M High Temp Silicone Gasket sealer can be used on intake manifolds, oil and transmission pans, timing chain covers, thermostat housings, and valve covers. It is easy to use by simply applying it to a clean and prepped surface area, and you can start the engine 15 minutes after application. Subaru specifies this sealer as a replacement for its OEM sealant.

The biggest complaint about this product is that if you don't use the whole tube at once, it has a tendency to dry out and can harden after a few months in storage. Also, it doesn't come with a graduated dispensing tube, which would make it easier to use.

Bar’s Leaks Head Gasket Repair is designed to tackle coolant leaks. It features a combination of aramid and refractory fibers that make it strong and heat-resistant. It penetrates leaks and forms a seal that is tougher than the original head gasket. The product is ideal for repairing blown head gaskets, stopping block leaks, and sealing cracked cylinder heads. This gasket sealer works as advertised. It stops leaks immediately, and the repair lasts for a long time as long as you follow the directions precisely. Some users report that their engines run a lot better after using this product and that the engines are smoother and no longer hesitate. In addition, this sealer is a little less expensive than some comparable products.

However, Bar's Leaks 1100 Head Gasket Repair is not compatible with antifreeze, and you must use it only after flushing and removing antifreeze from the cooling system, which can be a lengthy process. If you don't follow the process correctly, you can experience clogging issues.

Three Bond Engine Silicone Gasket 1211 is a semi-hardening sealer that is tough and durable. It uses silicone rubber and comes in a 3.5-ounce tube. It's designed for use on gaskets, crank seals, case matting surfaces, and more. It's tack-free within 90 minutes and cures in 24 hours. The product is comparable to yamabond and hondabond and can be used for both motorcycle and automotive purposes. It is thicker than Permatex Aviation and is easy to apply and clean up. It's great for everything from sealing engine cases and gaskets to sealing a timing chain cover or lawnmower case cover. A little bit goes a long way, and it has a metal tip cleaner to clean out the application tip so you can easily reuse it.

However, it takes a while to dry, and it's a little pricey. In addition, the sealer is white, which may not be the best option when it comes to aesthetics.