The thermostat on the Volvo V70 controls the coolant temperatures as the coolant exits the engine and goes back into the radiator. When the coolant temperature reaches 82.2 degrees Celsius, the thermostat lets more fluid flow through the engine to keep it from overheating. A faulty thermostat can create problems with the engine running too hot or too cold. Experienced home mechanics can replace the thermostat themselves to save money on a professional repair job.
Drive the Volvo V70 onto a set of front-end ramps. Secure the parking break and open the bonnet.
Remove the black cap from the overfill reservoir located to the left of the radiator. This releases pressure from the coolant system.
Remove the bolts that secure the lower radiator shroud to the bottom of the radiator using a socket and ratchet.
Place a drain pan under the petcock located on the driver's side, bottom of the radiator. Open the petcock with your fingers and drain two gallons of fluid from the radiator into drain pan. Close the petcock.
Reattach the lower radiator shroud by holding it against the bottom of the radiator, then threading the bolts in with your fingers. Tighten the shroud in place using the socket and ratchet.
Follow the upper radiator hose to locate the thermostat outlet housing on the top of the engine. The hose connects to the outlet. Pry the hose clamp off the hose with pliers and pull the hose off the thermostat outlet housing.
Remove the two bolts that secure the top of the thermostat outlet housing to the bottom part of the housing. This requires a T40 Torx bit. You can obtain a Torx bit from most automotive supply stores.
Lift the lid off the thermostat outlet housing and discard the gasket. Clean the mating surfaces of the upper and lower halves of the housing with a clean towel.
Pull the old thermostat out of the lower part of the housing and replace it with a new one. The end of the thermostat with the spring goes into the lower half of the housing.
Place the new gasket onto the mating surface on the bottom half of the housing, then put the lid on top of it.
Secure the lid to the lower half of the housing using the Torx bolts and the T40 Torx driver.
Slide the hose back onto the thermostat housing and secure it with the hose clamp.
Drain the two gallons of fluid into the expansion tank and close the lid.