Rick's Free Auto Repair Advice

Water pump gasket sealer

Should you use water pump gasket sealer

The most common question I hear about water pump installation is whether you should use water pump gasket sealer on the new pump. Here’s the correct answer

Unless the shop manual or water pump instructions tell you to use  sealer, do NOT use it. Here’s why.

NO gasket sealer on silicone gaskets, rubber O-rings or flat gaskets with impregnated rubber seals

Rubber O-rings and rubber seals on new water pumps are designed to be installed DRY unless otherwise stated in the installation instructions. Applying a water pump gasket sealer or room temperature vulcanizing (RTV) sealant can actually cause an O-ring or rubber seal to leak because it interferes with the compression seal designed into the product.

water pump gaskets

No gasket sealer on flat paper gaskets

Paper gaskets are designed to be installed DRY unless otherwise stated in the instructions. Shops and DIYers often apply RTV to the pump-to-gasket side in order to hold the gasket in place during installation. This is not the recommended procedure

water pump gasket

Paper water pump gasket

but can be done IF you don’t over-apply the RTV.

Excessive RTV that seeps into the contact area with the coolant will eventually break off or get pulled off by the circular coolant flow and either wind itself around the water pump bearing or spread through the cooling system and clog radiator and heater core passages, reducing engine cooling and heater operation. Water pump manufacturers do NOT recommend applying RTV or any gasket sealer unless specifically specified. If the gasket won’t stay in place, wet it with fresh coolant.

image showing excessive gasket sealer on water pump

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Posted on by Rick Muscoplat

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