How To Replace Your Geo Radiator

How To Replace Your Geo Radiator


The radiator and thermostat in your vehicle are responsible for controlling the flow of coolant through your engine. When your vehicle is overheating or having issues with temperature, this can cause your car to run rich and your engine to not perform as it should.

When this happens to you, it’s good to know how to replace your radiator and thermostat. This job can be done at home with hand tools and does not require the use of an automotive lift. Today we’ll be showing you how to replace your Geo radiator in a 2000 Geo Tracker. This vehicle is also the same as an Isuzu Trooper of the same year as well as the Honda Passport.

This Geo Tracker is powered by a 3.5 liter V6 engine, the 6VE1 and the part number for the radiator is Isuzu OE part number 89437-52755. This radiator can also be found under the Honda / Acura badge with the following part numbers as the interchange.

  • 89703-69333
  • 89723-70510
  • 89703-69321
  • 89703-69333
  • 89703-69351

We will also be replacing the thermostat in our How To Replace your Geo radiator DIY article. The part number for this unit is Isuzu part number 89712-31614. This is a 170 degree thermostat and most units include the o-ring seal that must be installed.

To begin our How To replace your Geo radiator DIY guide, first raise the front of your Geo and secure it safely. Always work on your vehicle with safety in mind first and foremost, for a good guide on vehicle safety check out our tips guide here.

With the front of your Geo Tracker raised and on jackstands, open the petcock located in the lower half housing of your radiator and drain into a bucket. After you have completely drained your coolant, begin by undoing the clamp on the upper radiator hose.


Disconnect the other side and remove the upper radiator hose all together. Now turn your attention to the lower radiator hose, which is on the same side and terminates at the thermostat housing directly under.


Disconnect the lower hose and set this to the side, now with both radiator hoses removed, you can now unbolt the radiator from the radiator support.


After removing all four 12mm bolts, you can now lift up and remove your stock radiator.


Now that you have your stock radiator removed, it’s time to undo the 10mm bolts and nuts that hold the fan shroud in place. Transfer these components to your new radiator to prep it. While the new radiator is being prepped, turn your attention to your thermostat housing which is held on by three 10mm bolts.

Remove these bolts, but do not start with the lower bolt first. All three of these bolts are the same size, which is unfortunate because the bottom bolt is very difficult to remove.  Remove the front and rear bolts, then you will need to carefully swing and use a bit of imagination to remove the last bottom bolt.

The reason you must do this is because this thermostat housing was installed before the motor was fully assembled. As you can see from the images below, that lower bolt must be a shorter version because the length it sits stock it runs completely into your air conditioning charge line.

When you install this part back on, you are best served by using a shorter bolt, it just needs to be slightly shorter. You can reuse the old one but it’s not ideal with your air conditioning compressor in the way.

What a bitch this last bolt is
What a pain this last bolt is

Once you have the three 10mm bolts removed, you should be able to rip off the thermostat housing and stock thermostat.


Remove and clean the surface of the thermostat housing and neck portion to make sure they are clean. Prep one surface with hi-temp gasket maker, and allow it to get tacky as you change your thermostat.


Make sure you clean the housing as best as possible, and remove the stock worn o-ring from the neck area.


Prep your new thermostat with the new o-ring and insert into the thermostat housing. Push on the thermostat neck with the shorter bottom 10mm bolt shoved through. You will want to thread this bolt in first, which will make your job significantly more easier.


Torque each one of the bolts to 12 inch lbs and give the hi-temp gasket maker some time to cure. You should give your vehicle a few hours before starting it and checking for leaks.

Now that your thermostat is back on the vehicle, it’s time to finish up the rest of our how to replace your Geo radiator DIY guide. Slide your new radiator with the fan controls and brackets re-mounted back into the vehicle and secure it with the 4 12mm bolts.

Once you have re-installed the new radiator, it’s time to reconnect the lower radiator hose first and finish our How To Replace your Geo Radiator article with the upper radiator hose re-installed.


Make sure to tighten everything up and let the gasket dry before starting up your engine again. Once you have it started check to see if your fans turn on once your engine warms up and that the thermostat housing is dry and free of any leakage.

That does it for our how to replace your Geo radiator article, if you have any questions or comments leave them for us below!