V8 Vantage Thermostat Replacement DIY Guide
DISCLAIMER
As always, follow all safety protocols. Don't undertake this task if you aren't comfortable with it, fully understand it, and are capable of completing it. The information provided may be incomplete or inaccurate. You are ultimately responsible for anything you do. Neither Redpants, LLC or myself is responsible or liable for anything that may occur.
WARNING
Let the car fully cool down before beginning!! Coolant systems are pressurized when at operating temperatures and will hold pressure for a while even after the engine is turned off. Opening any part of a pressurized coolant system can result in injury.
DO NOT open any radiator caps, coolant reservoir caps, thermostat housings, or coolant hoses until the car has completely cooled off!
The thermostat in the V8 Vantage tends to fail after around 5 to 7 years. More specifically, the gasket goes bad and either breaks apart or comes off entirely, either way preventing the thermostat from operating properly. In a “worst case” scenario, a chunk of the gasket could potentially clog a coolant passageway, which could lead to overheating issues. Since engine coolant should be replaced every 5 years or 50,000 miles, I recommend replacing the thermostat at the same time as preventative maintenance.
Needed
New thermostat and seal
Coolant (optional)
T30 Torx bit
T40 Torx bit
8mm socket
10mm socket
Extension and ratchet for the above sockets and bit
10mm box-end wrench
13mm box-end wrench
Pliers
Fluid pump, turkey baster, or other suction tool
Large, clean fluid container (2 US Gal / 7-8 L)
1-2 hours, depending on your pace
Torque Specs
Thermostat housing: 8-12 Nm. (6-9 lb/ft)
Thermostat housing support bracket: 23-27 Nm. (17-20 lb/ft)
Before you begin
You’re going to spill coolant when you do this job. You can drain some coolant from the radiator but that alone won’t empty coolant from the thermostat housing. You can also draw coolant out of the coolant expansion reservoir using a pump, turkey baster, or other tool. For the sake of over-explaining, I’ll include both of these as Step 1 in this DIY Guide. If you’re not draining anything, start at Step 2.
You can drain coolant from the radiator and coolant expansion reservoir into a large, clean container and reuse that coolant once finished. Make sure the container is clean and nothing gets into the coolant while it’s in the container - you don’t want to put dirty coolant back into the cooling system.
If you’re replacing your coolant, the OEM coolant is Havoline XLC. It’s available as a premix and also as a concentrate.
If adding water to your cooling system, use distilled water.
No matter what, I’d recommend lining the area under the thermostat housing with a plastic sheet or trash bag, taking special care to protect the FEAD belt and pulleys. Placing a towel or other absorbent cloth over the plastic liner will help contain the coolant as well.
Step 1
Raise the car with a lift or use a jack and jack stands. Then use the T30 and T40 Torx bits to remove the front undertray.
There’s a drain at the bottom right-hand side (US passenger side / UK driver side) of the radiator. Use that to drain coolant from the radiator, but be ready! Doing this cleanly is easier said than done! The coolant may splash off the radiator support brace.
Step 2
Disconnect the quick-release plastic tube that covers the PCV valve from the intake ducting. You only need to disconnect one end, circled in the picture below. This will allow you to push the tube out of the way.
Step 3
Disconnect and remove the quick-release plastic tube that goes from the PCV valve to the intake manifold. If you have a Redpants oil catch can (pictured in this DIY Guide), then you’re disconnecting the catch can hoses
Note: This would be a good time to remove the catch can entirely and drain it, since you’ve already done have the job!
Step 4
Use the pliers to release the clamp on the hose that comes out of the air-oil separator. The picture below shows the hose disconnected. You just need to pull this one side of the hose loose so you can push the hose out of the way.
Use the 8mm socket to remove the two bolts from the top of the PCV valve, circled in the picture below.
With the two bolts removed, you can pull the PCV valve up and out of the housing. Check the O-rings to make sure they aren’t damaged, and keep them in mind when reinstalling the PCV valve.
Step 5
Remove the 8mm bolt that holds the air-oil separator (AOS) in place, circled in the picture below. You don’t need to disconnect the hose from the bottom of the AOS since we just need to push the AOS aside.
Step 6
The wiring harness that runs along the top of the thermostat housing needs to be pulled aside. Pull the zip tie fir-trees free that hold the wiring harness in place using a fir tree pry tool or similar. It’s very common for these to be damaged when released, so it may be worth having extras ready to replace your original ones.
Step 7
There’s a bracket that sits on top of the thermostat housing, held in place by two nuts and one bolt (all 10mm), circled in the picture below. First,
The bolt is at the top of the picture. I found it's easiest to remove using the socket, ratchet, and extension, which will reach past the plastic tubes in front of it, but you can use the box-end wrench if you prefer.
The two nuts are at the bottom of the picture above. The one to the left is easy to access. The one to the right is a bit more tricky due to the stud it sits on being so close to the valve cover. Use the box-end wrench to get it loose and then it comes off easily. Be careful not to drop it!
Once the bolt and nuts are off, you can remove the bracket.
Note: Some people recommend grinding down the stud that’s close to the valve cover by 1/8” (3mm) to give more clearance when removing the bracket. It might take a bit of wiggling to get it over the stud but the bracket can come out without grinding.
Step 8
Remove the 8mm bolt on the bottom side of the thermostat housing. You should be able to get to it easily with the 8mm socket, extension, and ratchet.
Use the 13mm box-end wrench to get the two nuts on the top of the thermostat housing. The nuts are part of the studs, so they'll come out together. You should be able to wiggle the stud closest to the valve cover out, just be careful not to drop it.
Note: Once the 8mm bolt and 13mm nuts are loosened, coolant will start to leak out of the thermostat housing.
With the 8mm bolt and 13 mm nuts removed, you can now pull open the thermostat housing. In the pictures below you can see how bad the gasket was in my buddy Justin’s car.
Step 9
Unless you have a specialty tool, the easiest way I’ve found to remove the thermostat from the housing is to use my palm and press down on the center of the thermostat and rotate it to get it free. Be careful regardless of how you remove it - it’s literally spring-loaded and can pop apart in a few pieces if you don’t keep control of it when you let off the pressure.
If any part of the gasket is missing, check inside the thermostat housing to see if it’s still there. If you find anything, use pliers or something similar to remove it.
Step 10
Put your new thermostat together. It’s a bit wonky because it’s so loose-fitting, but it should look like the picture below.
Install it into the thermostat housing the same way you removed the old one - I use my palm to press it down and rotate it into place. Be careful with the pieces before they're in place as nothing is keeping them together in one piece until they're properly situation within the thermostat housing.
I highly recommend using a new thermostat housing gasket to help ensure you don’t have any leaks. I sell them packaged together with the thermostats I sell in my online store.
Step 11
Put everything back together! Assembly is the reverse process of the steps above.
Step 12
Make sure the radiator drain is closed and then top off your coolant to replace any that was drained or spilled during disassembly. If you stored your original in a clean container and it hasn’t been contaminated, you can add that back in. If you still need to top off a small amount and don’t have coolant, you can use distilled water instead.
And that’s it!