I just replaced my 2007 NA DOHC oil filter housing. There are other writeups, but I thought I'd try to make it simple. My car was leaking coolant, which was dripping onto the forward exhaust V band clamp, and I decided this was the most likely culprit. I ordered an OEM gasket from an online seller for $25.

I took off the the top of the exhaust header/catalytic converter heat shield on the front of the engine. I unbolted the V band clamp. I unbolted the header from the head. The cat/header would not come out.

I found out about Service Position, which is a fancy term for slide the core support forward. You do not have to disconnect the AC lines or radiater hoses. But, you have to unattach the fender trim from the front bumper and take off the front bumper. On the driver's side I pulled the trim all the way off, breaking all the plastic clips. On the passenger side, I found you can separate the front two push clip thingies without removing the trim. You can disconnect the bumper's electrical connectors through the removeable panels in the fender liners.

Then remove the four 16mm bolts in the front frame clip under the car on each side of the engine and the 4 bolts on each side of the bumper supports. Then the front slides forward far enough to remove the header/cat. Then you can replace the gasket in about 20 minutes. I reused my exhaust gasket but I had to buy new fender trim clips and some new fender liner fasteners. I haven't driven it yet because I'm waiting for those clips. It appears that the leak has stopped. I used Zerex G-48 I think for coolant? I bought it at Autozone. It is blue and says it is Mini approved.

 

I read somewhere that the cooling system should bleed itself. This did not turn out to be true for me. I filled the system via the catch tank and idled it a couple of times and topped it back up. I drove around a couple of times and the heater wouldn't warm up and the OBD2 scan gauge said only 70 degrees C. I wasn't happy about this and I am always scared about damaging the engine. Nevertheless my laser thermometer only found a temp of about 76 around the thermostat and everywhere I aimed it on the head.

Last night I bled the system with the bleed screw and now the heater is hot and the gauge is showing around 105, like it did before this repair. The bleed screw is hard to find, as others have said. It is right behind the ECT sensor.

I love these little cars but they really are no match for a 20 year old Honda in terms of design and engine performance (115hp from 1.6L with two cams and direct injection?) in my opinion. The only ECT sensor sits right where the air pocket forms in the thermostat housing. So when it's not wet you get no reading and the ECU will let you happily keep running, albeit with the thermostat open and the fan running all the time until you transfer metal from your pistons to the cylinder walls or blow the HG.