In terms of weight and cost, the benefits of plastic oil pans in motor vehicles over their metal counterparts can be extended even further when solid gaskets are replaced with suitable adhesive sealants. The two chemical companies BASF and Wacker have now succeeded in developing an optimally matched two-component system: the adhesion between the liquid silicone grade Elastosil 76540 A/B from Wacker and Ultramid®A3HG7 Q17 from BASF, a special polyamide 66 GF35, is so high that the integrity of the oil pan seal is assured under all common testing conditions. Extensive investigations at INPRO Innovationsgesellschaft mbH in Berlin have shown that no other adhesive/plastic combination exhibits such a high level of adhesion when sealing against aluminum. The tests included storage in oil and in a blowby medium (a condensate found in the crankcase of gasoline engines) and thermal shock tests between temperatures of -40 and +150°C.
The adhesive from the Elastosil Series is a two-component RTV silicone adhesive that is especially well-suited as a durable, leakproof seal between the Ultramid oil pan and the aluminium engine block. With such an adhesive, which provides a seal over the entire service life of the engine, the solid gasket can be dispensed with and the number of screw joints reduced. This translates into cost savings of 20 to 25 % per oil pan. Moreover, the flange geometry is free of stresses, since no compressive forces arise when using a vulcanizable sealant that is formed in place.