Hi,

My Focus 2002 Ghia 2.0l has a few symptoms, and my mate says it may be the head gasket.

I've been having problem with the engine light coming on and code P0420 coming up once a week and that pointed me to the cat converter. Today I checked the voltage of both the O2 sensors (pre cat and post cat) and they are both oscillating between 0.1 to 0.8V quicker than the multimeter can keep up. This tells me that the cat converter is shot. I'm also getting water dripping from the tail pipe and chuffs of white smoke when its revved. I also saw bubbles enter the coolant tank with the engine running.

Should I suspect the worse or just get the cat changed?

Thanks in advance!

Hi

I had a Renault Megane which blew a head gasket. The symptoms mine had were whitish gunk (mayo) under the oil filler cap, rough running, excessive steam from exhaust even when warmed up, bubbles in coolant and the coolant level dropping regularly. I'd take it to a garage pronto if you suspect hg failure. They can pressure test the system and test the coolant for contamination.

Thanks reprised

There is no gunk under the filler cap, but there are puffs of air (exhaust gases??) coming from filler when the cap's removed.

As well as bubbles in the coolant, there is a lack of pressure release when the coolant cap is removed hot.

There is a pool of oil or maybe coolant sitting on top of the water pump, which is directly below the edge of the rocker cover gasket that looks like it's spewing oil (though I only replaced the gasket recently and torqued the bolts to the correct setting).

There also looks like there is oil coming from round a bolt head that sits in a half moon bowl shape on the airbox side of the engine

Coolant level has gone down from mid way to min mark in the space of four months since I got the car.

Oil has only gone down in the last month or so from mid way to min mark (I topped this up)

However there are no running problems (yet!)

How common are Focus head gasket problems and do these symptoms fit? It is a 2.0l and so it may have been thrashed about in the past

I have videos of the steam from exhaust and also of the voltmeter reading on the post cat sensor that I can post if anyone's interested..

There is no gunk under the filler cap, but there are puffs of air (exhaust gases??) coming from filler when the cap's removed.

Lots of cars do that, some also run pretty rough when you remove the cap.

As well as bubbles in the coolant, there is a lack of pressure release when the coolant cap is removed hot.

Your coolant system is not holding pressure, could be a dodgy pressure relief cap, or head gasket.

There is a pool of oil or maybe coolant sitting on top of the water pump, which is directly below the edge of the rocker cover gasket that looks like it's spewing oil (though I only replaced the gasket recently and torqued the bolts to the correct setting).

You need to find out if it's actually oil or coolant.

There also looks like there is oil coming from round a bolt head that sits in a half moon bowl shape on the airbox side of the engine

Have you got a pic?

Coolant level has gone down from mid way to min mark in the space of four months since I got the car.

Could be a multitude of things, a leak, pressure relief cap, head gasket.

Oil has only gone down in the last month or so from mid way to min mark (I topped this up)

Could also be anything from a leak, oil control rings, valve seals, to a head gasket problem.

I have videos of the steam from exhaust and also of the voltmeter reading on the post cat sensor that I can post if anyone's interested..

Steam from the exhaust could be just from water in the back box once the car's warmed up.

I would get it to a garage to pressure test the coolant system, then you'll see where the coolant is going, it'll either run out, or drip out if it's a leak. That's the first thing to do, then you can worry about where the oil is going. If it's the head gasket you'll usually get water mixing with the oil (white foam), or combustion gases mixing with the coolant which can be tested by a garage, or a leak externally. Whatever you do, it needs to go see a mechanic.

the voltage of the lambda sensors is meant to go up and down, with the voltage being somewhere between 0.1 to about 1v

Have you got a pic?

Half moon leak

Location of half moon in engine bay

Half moon leak

Location of half moon in engine bay

Afraid I can't help you there. It's difficult to see exactly where in the engine that is. But it looks like it may be coming from the part further up on the 2nd picture, you can see the stains on the metal part (I think it's the cylinder head, but I'm not sure). I still think you need to get it pressure tested.

Thanks GavChap

I've had a closer look today and I believe that the oil patches around the engine bay look like they all came from the rocker cover at some point in the past.

I wiped around the edge of the cover at 10am this morning and the slightest dribble had appeared by 12.30.

As said, I only recently changed the gasket and tightened all bolts up in sequence to the correct torque 7nm

I was careful to seat the gasket in the guide correctly.

I am now wondering if oil is only being forced out because of a blocked/cracked PCV valve/hose. I've heard it's hard to get to and I'm not sure where it is.

I'm less worried about the head gasket now because a mate says he couldn't smell oil or petrol in the coolant, there was no water in the oil (cream) and said that the white steam from tailpipe wasn't constant and was probably condensation... having said that I'm still taking it for a Compression test next week.

I am now pretty sure I need a new cat, because he said that he could hear a suction noise/draw back of air through the tailpipe as the throttled is released.. and I already found that both O₂ sensors oscillate.

A new cat is £140 and I'll try and fit it myself, but I don't want to do it if it's only gonna be destroyed again by the engine... (I've never noticed overheating and the dash temperature gauge has never gone above normal). The car's done 69000, is it just about that time for a new Cat?

I noticed on last year's advisory note "Front Flexi Exhaust has minor leak of Exhaust gases"... could this constitute cat failure or water ingress?

So what does a coolant pressure test entail? is it expensive to get done at a garage? Is it something a DIY mechanic could do?

Also, on a drive down to Stansted on Saturday, I noticed every half an hour or so my headlights would dim momentarily (I have a DTC 9318, Battery Voltage Low stored on the dashboard diagnostic, but no battery light, could these be related?)

Is there anything else relating to any of the above I should look for?!!! Sorry to run on and on!

Thanks!!! :)

Coolant pressure test involves the garage putting a pump and gauge on your coolant tank instead of the cap, and pumping up the pressure to see if there's a leak, you'll know if the gauge goes down, then you have to find the leak. You can probably do it yourself, but the kit costs more (about £90) than you'd pay a local indie garage to do it.

As for your rocker cover oil leak, I'd probably buy a new gasket and re-seat it, taking care to clean both mating surfaces properly and torque the bolts in the correct order as well as the right torque.

"Front Flexi Exhaust has minor leak of Exhaust gases" is probably corrosion not the Cat. 69k is no miles at all. I doubt your cat has failed, only real way to check is to get it emissions tested at an MOT station. If your emissions are OK it's probably the lambda/o2 sensors.

Your headlights dimming might be the air-con, I had a car that did that, they just flickered when the air-con pump kicked in. Battery Low Voltage could be a bad connection to the battery, might want to clean and re-seat the battery terminals if they look a little corroded.