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Could you help me diagnose my oil usage problem?


jimmcwibb
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Hi all,

Focus Mk2 2.0L duratec

So I'm having to top my oil up regularly, I'd say I'm going through about 2 or 3L in a month. These are things I have done so far:

1. The obvious. Checked for leaks. Removed under tray and put paper underneath overnight. No drops, so no oil leak?

2. Checked throttle body for oil - it was nice and clean on the outside but black soot-like substance on the inside. It wasn't oily. (see photo).

3. Checked a spark plug. Looks ok to me? But there is oil on the threads. I've read that this is from a leaking valve cover gasket. Could this be leaking enough to cause my oil loss?

One thing I'm not too clear on. If the valve cover gasket is leaky, does that mean I might not see a leak with the car sitting overnight because the engine is not running and oil is not circulating? Also, does that sort of leak let oil into the cylinder? I'm a little hazy on where the spark plugs are actually sealed.

Any suggestions before I start thinking about checking the PCV? I'm a bit apprehensive about doing that myself...

 

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2016-10-02 11.02.44.jpg

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with that sort of consumption, im guessing its just burning it , duratec known to burn quite a bit of oil when they age. 

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Yeah. So it's getting past the piston rings? 

Edit: by the way, it's got 79k miles on the clock (genuine from MOT history...)

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could be, the 1.8 were worse for some reason.

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If the Valve cover gasket is leaking you would not see oil underneath the car as it would only leak from there as the engine is running due to it circulating. when the engine is not operating it would not leak oil as the engine is not circulating the oil.

I would definitely examine a leaking valve cover gasket for a leak, it is fairly easy to replace and the gasket shouldn't cost more than £20- £25.

 

I wonder if your piston rings are worn , if your turbo is bad, or maybe valve seals ?

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OK, so valve cover definitely warrants further investigations. I'll have a better look at it.

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if you were losing oil via valve cover gasket at a rate of 2-3 litres a month , then you would see lots of oil dripping off bottom of engine

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Yeah there is that. But also, if I was burning that much oil wouldn't my spark plug look a lot worse? Admittedly I only pulled the one.

My plan of action is to get someone to drive behind me and look for blue smoke, pull all 4 spark plugs and look for signs of burning oil, and investigate the rocker cover gasket, and get under it again and have a proper look for any signs of dripping oil, especially after going for a drive.

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Alright so this morning my friend drove into work behind me and said there was no smoke except when I first set off (floored it getting onto a tricky roundabout). But the rest of the drive in, 20 mins with lots of gear changes and revving to try and make smoke, nothing.

I think this fits with the state of my spark plug, which looks fine. I haven't pulled the other three yet, I'll do it this weekend. But I can't see how I could be burning ~2L of oil a month without making quite a lot of smoke?

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  • 2 weeks later...

I hadn't made much progress on this problem (couldn't find definite signs of a leak after cleaning around the rocker cover). So I was googling about oil leaks this week and found out about UV oil dyes. Well it just so happens that I already have a UV torch for my marine fish tank so I spent £8 on the dye and it came today.

I added the dye to the engine, and went for a 20 minute drive. On inspection, I couldn't find any dye around the engine block but there were hints of some around the boot of the coil packs. I was kicking myself at this point because I should have done an inspection with the UV torch before adding the dye, so that I knew if any glowing was new. Anyway I pulled the coil pack and peered in, and found the spark plug sitting in a pool of luminous oil (see pic).

So, that's a good few mL of new oil that has leaked after just a 20 minute drive. I'm pretty sure that will go a long way to explaining my oil loss.

Next job - replace rocker cover gasket!!

2016-10-20 12.29.48.jpg

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Quick question, is there supposed to be any oil in the breather hose that connects to the back of the rocker cover? I found oil there today, inside the pipe and coating the plastic connector.

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Well I replaced my rocker cover gasket on saturday. One of the middle bolts was definitely not torqued up so that's why it was leaking. The gasket itself looked OK but I replaced it anyway.

So far so good. No more oil around the spark plugs. There is oil in the breather hose and some in the air box where the breather hose connects under the filter, but nowhere near enough to explain my usage. Time will tell if I have to top up my oil again.

Isn't it a bit mad that the breather hose connects before the air filter? So the crankcase gets air that's only filtered by that little sponge where the breather hose connects to the air filter box?

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17 hours ago, jimmcwibb said:

Isn't it a bit mad that the breather hose connects before the air filter? So the crankcase gets air that's only filtered by that little sponge where the breather hose connects to the air filter box?

The direction of airflow is always out of the crankcase due to the fact that it's pressurised by combustion gases leaking past the rings.

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