How-To: Install a Thermostat on a SC400


New Member
Hello all,

I've recently replaced the thermostat on one of my customer's cars, a lovely silver '98 SC400, and would like to share a brief D.I.Y walk-through on the procedure :D

1) Disconnect the negative battery cable from the battery.

2) With the engine cool, position a drain pan under the radiator drain cock and drain the cooling system.

3) Loosen the hose clamp and disconnect the lower radiator hose from the water inlet housing.

4) Remove the two nuts from the water inlet housing and remove the housing from the water pump studs.

5) Remove the thermostat and rubber O-ring gasket from the water inlet housing.

**To install**

6) Make sure all the gasket surfaces are clean. Clean the inside of the inlet housing and the radiator hose connection with a rag.

7) Install the new rubber O-ring gasket onto the thermostat.

8) Insert the thermostat into the housing.

9) Position the water inlet housing with the jiggle valve of the thermostat aligned with the protrusion of the water inlet; install the two nuts. Torque the two nuts to 8–13 ft. lbs. (9–18 Nm).

10) Connect the lower radiator hose to the inlet housing and install the hose clamp.

11) Fill the cooling system with coolant.

12) Connect the negative battery cable to the battery.

13) Start the engine and inspect for leaks. Bleed the cooling system.

SC400 Thermostat diagram
wow that is the hi tech way!

I just pulled the thermostat housing off, pulled the old one out put the new one in, put the housing back on and topped up the coolent :p

reprogramming stations into the radio is way too hard :p


Active Member
u forgot to say

remove the 17mm bolt at top of housing area
then fill up with coolant
then once water comes out of that bolt hole and all air bubbles are gone
then refit and tighten bolt
do not try to bleed with engine running as it pumps water out of the top bolt hole