Can RTV Ruin A Modern Gasket Seal Or Is It Still Ok To Use?

Have you had to replace, repair, or reattach an oil pan or transmission pan, lately? Then someone probably recommended you use RTV to seal it. These are pretty common uses for this product, as it can be utilized to create a brand-new gasket. Some automotive manufacturers have begun using RTV instead of regular gaskets to seal certain parts, like oil pans.

RTV, which stands for Room Temperature Vulcanizing, is a silicone rubber compound that is designed to cure and harden when it is exposed to the moisture in the air, which happens when it is squeezed out of an airtight container. As the name suggests, this curing process can take place at room temperature, without applying any additional heat. An additional property is that it acts as a sealant between two surfaces and works great with metal. These advantages make it ideal for replacing automotive gaskets when properly applied. Popular brands include Permatex, Wynn’s, Realth, J-B Weld, and V-Tech.

For mechanics, it is often more convenient to use a tube of RTV that’s already on hand in their shop than to locate and buy an OEM gasket that fits. Other repair situations require making a gasket on the spot, especially when the part came out of the factory with RTV in the first place instead of with a manufactured gasket. Either way, RTV has become more common in the automotive industry, so let’s look at when you might need it and what you should be aware of.

It’s understandable if you’re hesitant to use RTV on your DIY repair. After all, it’s messy, it takes time to cure, and it can leak if applied improperly. It’s hard, but not impossible, to mess up applying a regular manufactured gasket. So, if an OEM or quality aftermarket gasket is readily available, it may make sense to use it rather than to apply RTV.

However, some mechanics still prefer to use RTV, especially on transmission pans. Some cork or rubber gaskets can tend to slip, and when this happens, the seal is ruined, and transmission fluid will leak. Sometimes, a proper replacement gasket just isn’t readily available, or the part was originally sealed with RTV by the manufacturer. There are also times when the manufacturer itself recommends using RTV to seal the part. In these cases, you will need to use an RTV product.

To apply RTV, make sure to thoroughly clean the surface and use a plastic scraper to remove any remnants of the original RTV or gasket. Apply a continuous, thin bead of RTV on one of the mating surfaces by using even pressure when squeezing the tube. Apply the RTV in such a way as to encircle the bolt holes. In the case of a transmission or oil pan, tighten the pan finger-tight, wait an hour, then tighten to the proper torque. Wait 24 hours for the RTV to fully cure before refilling the pan with fluid and keep an eye open for leaks.

There are cons to using RTV, but these generally arise from misuse. For example, some have used RTV on top of an existing gasket for extra adhesion. However, that’s not how RTV works and is too thick for this application. Use a proper gasket sealant instead for this purpose.

Another mistake is to use too much RTV. This is an issue that arises on both DIY job and from manufacturer error, as was seen when Toyota had to fix a GR86 engine that failed due to an overapplication of RTV. Excess RTV can squeeze out and create clogs. Make sure to apply a thin, continuous bead. As long as the bead is continuous, with no gaps or holes, you shouldn’t have any leaks.

You will also want to avoid using RTV where it is not meant to be used. For example, you would never want to use RTV on a head gasket or where it might come in contact with gasoline. Other mistakes include not giving it enough time to cure, using a metal scraper instead of a plastic one to remove an old gasket, and not properly cleaning the surface before applying the RTV.

Overall, RTV can be a reliable and easy-to-use product for sealing parts and creating gaskets. Just be sure to follow instructions specific to the product, use the right product for the job, and to take your time so that you can apply it correctly. Doing these things can ensure that you have a tight replacement seal that is free of leaks.