Ford Focus ST170

A great car... but you need to know more about it. Yeah, admit it.


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Replace the Rocker Gasket Seal

For a while, I noticed there was an oil leak around my engine of my ST170 and it has been bugging me for a while. So I decided I need to look into this in case it was something serious. And I tracked it down to a possibe split gasket seal on the rocker cover, so I ordered the parts I needed and waited until the weather was nice to allow me to do this job.

Before I start, here are the list of tools you need for this job:

  • 8mm socket
  • 10mm socket
  • Torque wrench
  • Brake cleaner
  • Some old rag
  • Rubber gloves
  • Safety glasses
  • FINIS 1222181 - Rocker gasket seal
  • FINIS 1037627 - 10 x "O" ring seal aka Grommet

Here are some of the items used for this job - sockets, new gasket and "O" rings.

First of all, here is my engine bay. Excuse me for the dirt! :D Click for bigger picture...

Move the throttle cable out of the way. I put it over the radiator tank. Then remove the coil pack cover on the right side. Now using the 8mm socket, unscrew 4 of the bolts that is holding down the spark plugs cover. Store them safely.

Remove the spark plug cover. If you want to, mark each lead with a number. Number 1 is on the left all the way to number 4 on the right. Unplug them by pulling out from the rubber edges and not from the lead itself.

Ensure the leads are out of the way. Now using the 8mm socket, unscrew two screws on the cam cover on the left. One is near the power steering pipe and the other one near the fuel injector. This will allow you to remove the rocker cover easily.

Now before you remove the rocker cover, you need to unplug the oil breaher tube (top right of the engine, the pipe leads to the air filter box) and cap it to stop the oil leaking. Also you will need to remove the Variable Valve Timing (VVT) plug - there is a pin clip - unclip it. You now should see something like this. The next step is to unscrew all 10 bolts around the rocker cover using the 8mm socket.

Push the cam cover out (toward the radiator tank) and lift the rocker cover up, taking care not to scrape/damage the VVT. And now you can see the insides of the engine. Ensure that you do NOT let any other foreign objects, dirts, liquid, etc into it.

Now using an old rag, wipe out all remaining oil/dirt around the edges, making sure that it does NOT fall into the engine bay. Wipe it outward and not inward to the engine bay. Make sure every traces of old rubber, sealant, and gasket are removed from the edges so it will have a smooth finish. This is what it looks like after cleaning.

Now let's have a closer look at my issue - as you can see, the gasket are split. Same goes with the bolts' "O" rings.

We'll start with the bolts - remove all "O" rings from them and clean it up to remove any traces of old rubber/dirt.

Make sure you do NOT fit the "O" rings as shown in this photo as that's what many people (including myself) thought it was right but it's not. Turn it round and you're sorted!

Now, to the rocker cover... health & safety alert - put on your rubber gloves, wear a safety glasses and whip out the brake cleaner spray - it's not very nice to your skin & eyes!! Using a brush or kitchen towel, spray on the rocker cover and clean it.


Ensure that all traces of gasket/rubber are removed from it too.


Now fit the new gasket - making sure that all edges are tucked in correctly without anything sticking up/loose.

Back to the engine - fit the rocker cover down to the engine block carefully, ensuring that you move the cam cover out of the way before putting it flat down. Then hand-tighten the bolts before using a torque wrench to tighten them. The 1st stage is 2Nm and the 2nd stage is 7Nm for final tightening. Remember to do them in correct order (i.e. 1st bolt, bottom left corner, then 2nd at top, right corner, 3rd, bottom right corner, 4th, top left corner and so on) to ensure it is being tighten equally across the rocker cover.

Plug the VTT in, insert pin clip to secure the plug, plug all spark plug leads in and plug the oil breather tube. Tighten up the cam cover. Put back the throttle cable.

Finally, put the spark plug cover back on, screw them down using the 8mm socket, put back the coil pack cover. At this point, I started cleaning up the area around it.

Start the engine and let it idle for a while. Look around the engine for any sign of oil leak. If no leak after 5 minutes of running, go for a steady drive, stop somewhere and double check to ensure all is good. Also check the oil pressure/temperature gauges too to ensure all is OK. If no problem, then the job is done and you've saved money! :D