Repairing the Leaky Air-Oil Separator in an Aston Martin V8 Vantage

I discussed a few of the faults of the OEM air-oil separator (AOS) in this blog post. If you've got a leaky AOS, this DIY guide will show you how to fix it.

DISCLAIMER: As always, follow all safety protocols. Don't undertake this task if you aren't comfortable with it and fully understand it. You are ultimately responsible for anything you do. Neither Redpants, LLC or myself is responsible or liable for anything that may occur.

New AOS (OR) new o-ring
8mm socket
1/4"-drive ratchet
Short extension
Blunt-nose pliers (or similar)
Hook-end pick (if replacing the o-ring only)
Paper towels (maybe)
10-15 minutes

First, make sure you let your engine bay cool off if you've just been out driving. It is also a good idea to have a paper towel or two handy in case you drip any oil. I did not need one when I installed my new AOS, nor did I need one just now when I pulled it to take the pics below. But it's better to be safe than sorry!

Here's the location of the AOS:

If you pull up on the hoses above it, you can look at it from the driver's side of the car and see the whole AOS and the 8mm bolt that is holding it in place.

Step 1
Remove the 8mm bolt and set it aside.
With the bolt removed, you can move the AOS around quite a bit - the hoses have lots of flex in them. This will allow you to move the AOS however you need to so you can use your pliers to remove the two hoses that are attached to it.

Step 2
If you're installing a new o-ring but keeping the AOS, jump down to Step 2A.
If you're installing a new AOS, jump down to Step 2B.

Step 2A
Use the hook-end pick to remove the old o-ring, then put the new o-ring in its place.
Once done, go to Step 3.

Step 2B
Use the pliers to squeeze together the tabs on the hose clamps and work the clamps an inch or two down the hose. Pull the two hoses off the AOS. Put the new AOS in place and attached the hoses.
Once done, go to Step 3.

Tip: Rotate the hoses back and forth as you remove them from the AOS to break the seal of the rubber-on-plastic that has been created over time. As you're pulling the hoses off, keep twisting the hose back and forth as you pull. This will make removal much easier. Do the same as you push them back on.

Step 3
Reinstall the AOS by following the steps you just did in reverse order.
Make sure there in an o-ring on the new AOS (see above image).
Put the AOS in place and bolt it in with the 8mm bolt. Do not over-tighten as it is going into an aluminum housing.

And that's pretty much it! Just make sure everything is fastened and secure and you should be good to go.