The use of the blanking sleeve in place of the thermostat is used to slow the coolant so it does not flow to fast passing thru the radiator. To fast of a flow the coolant does not have time to cool sufficiently. If you are still having overheating i would suggest installing a 195 deg thermostat.

Blanking Sleeve - "A" Series - BMC

SKU: THR-103
$14.75Price