We have several upgrades to the cooling system we suggest doing and adding an expansion tank is 1 of them.

Before we begin, it should be clear that there are 2 basic types of radiator caps used on the old Volvos and although they look identical, there is 1 big difference and that is the length of the plunger. There's a 1" deep radiator filler neck and a 3/4" deep neck. BTW this also applies to the Volvo expansion tanks as those were made in both styles.

To add an expansion tank to any Volvo cooling system with a pressure cap on the radiator, we use a blanking cap to seal the radiator fill neck and connect the expansion tank to the stock radiator dump tube using the correct style of coolant recovery hose and it's not fuel hose.

If you have the early expansion tank that has a 1" deep neck, we use a 7 lb pressure cap. If it's the later tank with a 3/4" deep neck, then we use a 13 lb cap.

If we're doing a radiator service at the same time, we recommend replacing the 1" upper and lower radiator hose barbs with 1 1/4" barbs on the radiator for better flow. Larger hoses and the 1 1/4" thermostat neck also need to be installed at the same time.




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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com