When to Apply RTV When Replacing a Valve Cover Gasket
When considering the replacement of a valve cover gasket, one critical question often arises: is it necessary to apply RTV (Room Temperature Vulcanizing) sealant? This article explores the conditions and scenarios where RTV application is beneficial, and when it is not required at all.
Understanding RTV Sealant
RTV sealant is a versatile substance widely used in automotive applications to enhance sealing and prevent leaks. It is particularly useful in areas where traditional gaskets alone may not provide a sufficient seal. RTV sealant can cure into a rubber-like substance that forms an airtight and watertight seal.
Factors to Consider Before Applying RTV
1. Type of Gasket
The type of gasket you are using is a crucial factor in determining whether RTV is necessary. Rubber or cork gaskets specifically designed for the application might not require additional RTV. These gaskets are often engineered to create a proper seal on their own, eliminating the need for additional sealant.
2. Manufacturer Recommendations
Always refer to your vehicle's service manual or manufacturer’s recommendations. Some manufacturers specify whether RTV should be used, often based on the specific make and model of your vehicle.
3. Surface Condition
The condition of the sealing surfaces plays a significant role in determining the applicability of RTV. If the surfaces are not perfectly smooth, applying a thin layer of RTV can help ensure a better seal. Imperfections or rough surfaces can lead to gaps where leaks might occur, making RTV essential in these cases.
4. Previous Application
If the original gasket had RTV and there were no issues, you might consider using it again. However, if the previous sealant did not perform well or caused contamination, it is best to start fresh with a clean gasket and possibly new RTV.
5. Joint Design
Certain engine designs may require RTV in specific areas. For instance, at the corners or where two different materials meet, RTV can provide additional support and prevent leaks. Engines with acute angles where a gasket needs to fit against may also benefit from RTV application.
When Not to Use RTV
While RTV can be beneficial in many situations, there are also scenarios where it is not recommended. The slimy consistency of RTV silicone can cause gaskets to slide under pressure as screws are tightened, potentially leading to poor performance. The gasket should be allowed to 'squish' into place rather than slide or shift.
Additionally, RTV is generally not used on valve cover gaskets because its sticky nature can interfere with the proper seating of the gasket. You want the gasket to seal against the surface of the block or head, not to slide or shift due to the adhesive properties of RTV.
A Comprehensive Guide
The decision to use RTV depends on the specific gasket and engine in question. Historically, gaskets have evolved from plain cork to rubber, and finally, to o-rings that compress when cover fasteners are tightened. Some more complex designs may require RTV to seal at junctions where various components meet, such as the head, block, intake manifold, and front cover.
RTV can help many styles and designs seal a bit better, but it may not always be necessary nor recommended. Where multiple parts come together, RTV sealant can help ensure no seepage at those junctures. Therefore, it is crucial to assess the specific requirements of your engine and gasket before deciding whether to use RTV.
Conclusion
In summary, while RTV is not always necessary, it can be beneficial in specific situations. Always follow the specific guidelines provided by your vehicle's manufacturer to determine the best approach. For optimal performance and reliability, ensure that the gasket seats properly without sliding or shifting, and use RTV sealant only when it is truly required.