891610 - Focus ST Air Oil Separator
2015-2021 Focus ST
Congratulations on your purchase of the COBB Tuning Air Oil Separator! The following instructions will assist you through the installation process. Please read them BEFORE beginning the install to familiarize yourself with the steps and tools needed. If you feel you cannot properly perform this installation, we HIGHLY recommend you take the vehicle to a qualified and experienced automotive technician.
Parts List
Tools Needed
Sockets
3/8"
3/8" ratchet
3/8" 12" extension
3/8" 6" extension
3/8" Socket Swivel
3/8" 7mm socket
3/8" 8mm socket
3/8" 10mm socket
3/8" 12mm socket
3/8" 13mm socket
3/8" 10mm deep socket
3/8" 4mm Allen Socket
Hand Tools
Phillips head screwdriver
Trim removal tool
Pick
Prep, Intake Manifold Removal
Remove the plastic engine cover by gently pulling up to release the clips.
Loosen the 2 hose clamps connecting the two halves of the intake pipe using a 7mm socket. If you have a COBB intake installed you’ll need to use an 8mm to loosen the coupler at the throttle body.
Loosen the hose clamp holding the intake pipe to the airbox. (7mm stock, 8mm COBB)
Remove the rubber grommet from the mounting location securing the electrical harness to the intake pipe.
Unbolt the intake from the top of the valve cover (10mm)and remove it or swing it out of the way.
Undo this clip near the master cylinder to allow some movement in one of the emissions lines.
Unplug it at the other end by pushing in on the release button. This is located on the upper right hand side of the intake manifold.
Remove the emissions line from the clips on top of the intake manifold.
Unplug the MAP sensor connector.
Unplug the MAP sensor connector.
Loosen the hose clamps from the throttle body to the intercooler using a 7mm, 8mm, or screwdriver depending on what fits or is easiest.
Using a 10mm and an extension to remove the bolts holding the intake manifold to the cylinder head.
Gently pull the intake manifold away and reach behind to squeeze and release the pcv hose on the back of the manifold.
It's sometimes easier to reach around the manifold and depress the clip with one hand for each side. (Hugs are nice)
The textured parts of the clip are the sections you'll want to squeeze in to release the hose.
Squeeze the sides and pull out the green connector to release the hose above the throttle body on the left-hand side.
Pull the manifold up so you can disconnect the throttle body. Pull the red locking tab out first, then squeeze the tab to remove the connector.
There are also two electrical connectors clipped to the intake manifold on either side that will need to be popped off with a trim tool.
With those removed you should be able to remove the intake manifold from the engine bay. Tape off the intake ports and cover the coupler going to the intercooler to make sure nothing gets inside the engine.
Using an 8mm socket remove the factory breather plate from the car. You may want to put a towel underneath it as there will probably be a small amount of oil that drips out once the plate is removed. You will probably need to use an 8mm wrench for the bottom one closest to the cabin of the car, as the motor mount can be quite tight to it.
Pre-Assembly
Pull out the provided gasket and breather plate. Lightly grease the gasket with the provided silicon lube on all sides then install it into the plate. The gasket is molded and will only go in one direction, there is a small tab on the gasket that sticks through an opening on the plate, from there it’s just a matter of seeing if it’s upside-down or not.
Lubricate the o-rings and install them on the threaded ends of the barbed fittings
Install the AOS bracket to the CAN using a 4mm allen key and the 3 button head allen bolts.
Install the barbed fittings onto the can, the small one should go on the very bottom. You’ll want them set in this orientation (though even after they’re tight you’ll be able to move them around some. The larger fittings will get tightened with a 27mm and the smaller one with a 19mm. These just need to be tightened until they come to a stop.
Using the fittings you took from the stock pcv plate, Install them into a short length (around 3”) cut from the smaller 1/2” loose hose provided in the kit. Secure it with one of the provided spring clamps, then slide an additional spring clamp on to the opposite end of the cut hose, before installing it into the smaller end of the provided plastic adapter fitting. Repeat this with both fittings.
Cut the 5/8” hose into a 20” section and a 17” section. (you can cut these to different sizes if you want to route them a different way.) Using the adapter sections you just made, add the hose onto the larger end of the plastic adapter using the 5/8” clamp, then pre-install a clamp on the other end of the hose to get your two breather lines.
AOS Can Installation
While this can be done with the manifold back on and sometimes makes things a little easier. I like to do this early because I drop bolts every single time I do this, and being able to get to them is important to me.
On the bottom tab of the can, install the m6 x 1.0 x 30mm hex bolt with a washer on one side of the bracket. If you don’t have the active engine mount package (HP pack only) you’ll want to install the provided aluminum spacer.
It will now get installed to this threaded bolt hole on the strut tower. If you have the fancy motor mount there will be another plate here that you’ll bolt through without the spacer.
With that loosely bolted in place, use the smaller M6 x 1.0 x 16mm bolt with a washer from the top of the upper bracket, through the bracket sticking out from the strut tower top. Then secure it with a washer and the provided m6 lock nut on the bottom side.
Tighten down the upper and lower bolts with a 10mm socket or wrench.
Breather Plate Installation
The breather spacer plate will sit behind the stock plate to allow the installation of a drain line to make the AOS can service-free.
Stack the stock breather plate together and slide two of the provided longer m6 bolts to the bottom two holes of the plates to hold them together. These are also the hardest to get into place if you do them later due to where the motor mount sits. Slide this into place against the block (making sure nothing is behind the plate, and get the two lower bolts started by hand.
With them started but definitely not anywhere near close to tight, route the drain line up and towards the driver’s side (usdm) strut towerkeeping it away from the steering rack and any wiring harnesses. If you’re happy with the routing of that one you can go ahead and install it to the bottom fitting on the AOS can using the provided 3/8” spring clamp.
Go ahead and loosely install the remaining bolts for the breather plate assembly. Most can get tightened with a 10mm socket, but the bottom one nearest the motor mount may require a wrench to tighten depending on the clearance you have. These should get tightened to factory specs. (89 in/lbs)
Hose Installation and Reassembly
Take the hose with the 17” section of 5/8” hose and connect it to the PCV valve coming off of the breather plate. Pre-install a 5/8” spring clamp on the bare end and slide it ~4” down the hose. Route it underneath the metal hose section and up to the fitting on the side of the can. Slide the hose all the way up until it’s pushing on the hose stop then slide the hose clamp up on to the barbed portion of the fitting to secure the hose to the fitting.
Connect the longer hose to the fitting on the intake manifold.
Re-install the intake manifold, making sure to route the newly added hose forward in a way that it doesn’t hit or rub on anything else. Make sure to get the lower bracket and stud into the manifold before you tighten the manifold down!
With the manifold tightened and the harnesses on the back-side reattached to it, you can go ahead and add the final 5/8” hose clamp to the hose to the manifold then route that under the intake tube for the throttle body and up to the top tube on the can, securing it by sliding the hose clamp up.
Once that’s done you can reassemble the rest of the engine bay back to gether and you’re all done!
CARB Sticker Application
(Where Applicable)
Apply the supplied CARB sticker in a clear, easy to find location. Typically underhood, or on the radiator core support.
Links
MAP Notes
Helps to figure out which map you should be on given the parts installed to your car
Links for related parts