Valve covers can be hard to seal. That’s because they’re often made from thin material that bends as the fasteners are tightened. The result is uneven compression of the gasket material, which often leads to leaks. If you’re looking for a valve cover gasket for industrial equipment or an engine application, here’s what to consider.
Standard Gasket Material Factors
As with every gasket application, the first points to determine are:
- Temperature of the media being sealed
- Environment – where the gasket will be placed in service
- Media – does it have corrosive properties and what gasket materials is it incompatible with?
- Pressure – the load the gasket will be subjected to determines the material strength needed
Establish these and you’re on your way to determining the best material for your valve cover gasket, but there is one other point to consider.
Dealing with Deflection
If the valve cover is likely to deform as it’s tightened down the gasket material needs enough compressibility to not leave any gaps. This leads to softer, (lower durometer, in the case of elastomeric materials), and thicker materials. Softness ensures sufficient deflection while thickness matters because of the percentage deformation needed. (1/16” deflection is a smaller percentage of gasket material ¼” thick than if the material is only 1/8” thick.)
Candidate Gasket Materials
The application will determine the material. If you’re sealing a valve cover on a diesel engine with high temperatures and oil, an aramid fiber gasket might be the right choice. (Frenzelit Novatec® fiber with graphite gaskets provide good chemical resistance and handle high temperatures.)
Elsewhere, perhaps in air compressors or covers over industrial valves, rubberized cork can be effective. In select cases NBR gasket material or EPDM gasket material may work well too.
Replace, Don’t Reuse
It can be tempting to reuse a valve cover gasket when the joint was only opened up for an inspection. Don’t do this.
Most gasket materials take a compression set. This means they don’t spring back to their original thickness. The amount may be too small to see, but reusing the gasket risks leaks.
Contact Hennig Gasket & Seals for custom sealing solutions.
