How to reroute coolant

  • Coolant reroute kit (contains also gaskets, bolts and other useful stuff)
  • Thermostat housing from NA (MK1) 1.6 engine (part number B61P-15-172) or Kia housing* (0K24715172A)
    *Caution, it has Ø35mm diameter, so you need a soft hose (like the Mazda ones)!
  • 1m Ø32mm flexible hose or 1m hose with 100° bend or Gates 22436 or Dayco 71989
  • Ø32mm coolant hose joiners/couplers or 32mm outer diameter aluminium pipe
  • Some hose clamps for the hoses
  • Coolant liquid to top up or replace in case you decide to change your current one
  • Basic tool set (spanners, socket wrench, screwdrivers, knife)
  • We also recommend a new one-valve thermostat (88°C for standard street use)
  1. Be safe. This is a simplified step-by-step guide on how to install a coolant reroute. It is not a service manual and installation should be attempted only by a person with some experience. When not sure what to do, take your car to a professional service. We cannot be held liable for any damage which might occur during the installation.

Prepare the car

  1. When the engine is cold, drain the coolant and dispose it properly
  2. Optional: remove the coils for better access (don't forget to mark the leads!)
  3. Optional: remove the cam angle sensor (CAS) for better access (mark it's position first + take a photo of inner rotating mechanism's position too, you will use those to fit it back)
  4. Note - for some 1.8 engines you need to remove the bottom mount on the coil bracket in order to install reroute spacer. Removing it does not cause any issues, many cars will have this mount cut off already as it makes changing the timing belt easier.

Disassemble front coolant piping

  1. Disconnect coolant hose from top of the radiator and the engine block
  2. Remove thermostat housing cover from front of the engine
  3. Clean the parts from old gasket remainings

Disassemble rear coolant piping

  1. Disconnect heater hose from back of the engine
  2. Remove the heater outlet
  3. Remove the threaded stud using a spanner and two nuts locked to each other
  4. Clean the parts from old gasket remainings

Install front blanking plate

  1. Bolt the blanking plate with new gasket under it to the front coolant outlet
  2. MK1 (NA) 1.6 only: install the front fan switch
  3. Optional: you can remove the whole outlet and freeze plug the engine

Install rear spacer and housing cover

  1. Plug the threaded hole on the thermostat housing cover (a bit of epoxy can help to seal well) - does not apply if you are using the Kia housing
  2. Put the thermostat to the groove in reroute spacer, weep hole should be at the top
  3. Attach the thermostat housing cover to the spacer, put bolts through the holes
  4. Gaskets should be between each two metal parts (engine-spacer and spacer-housing)
  5. Carefully bolt the assembly to the back of the engine
  6. Install temperature sensor to the coolant reroute spacer

Connect the piping

  1. Rotate the original hose on top of the radiator 180°, so it goes around the engine
  2. Make a hose connection from the back of the engine to the radiator inlet hose
  3. Reconnect heater core input hose to the barb on the spacer

Test the rerouted cooling system

  1. Fill the radiator with new coolant liquid, squeeze the hoses a few times
  2. Start the car and check for leaks, check if thermostat opens (hoses should get warm)
  3. If everything is fine, bleed the air from the system
  4. Do a test run, let it cool down, then check everything again and top up the coolant
  5. Enjoy and share your build with others