Thought I'd make a post about the issues I've had with my Megane 1.9dci.
Got the car very cheap from my Brother who works in the trade. The car had blown its turbo, which was replaced with a brand new one.
First few days, I fell in love with it. Plenty of power,quiet,handles well, what else do I need to say. After a couple of weeks, I chucked her round a sharp right hander, and the oil warning flashed up briefly. The oil level indicator on the dash is crap, DO NOT trust anything they say. Topped it up, and carried on. A day or two later, the engine "ran away" using its own engine oil. Luckily, it was at low speed, and a stamp on the brakes to stall her, prevented it revving freely. Started it, and away it went no problem. It did this once more, before I had chance to read up on this forum about possible causes.
On opening the bonnet, I noticed oil pooling under the damper valve, so somehow oil was making it through the turbo, and into the intercooler. I suspect, that because the engine now had the correct amount of oil in it according to the dipstick, the level was higher, making this possible.
My solution:
Remove the oil seperator pot on the front of the engine. When I did, oil ran out of it. It did this because the pipe that runs from the bottom of it, back to the sump, was absolutely blocked solid. I cleaned the whole thing, and made sure the pipe that runs into the sump was clear. It's not very big, and easily becomes clogged. When it does this, oil fills the tank, which is then drawn out of the top of the oil seperator, through the PCV valve, and into the inlet system.
All cleaned and sorted, I kept my eye on things.
It seemed ok, so decided to take the car to France. Watching like a hawk, it became apparent she was still burning oil, and at a higher rate than it should (about 500ml/250 miles). I kept it topped up, and brought her home. Incidentally, the run down to Bordeaux, returned 48.1 mpg ! and I was "making progress" occasionally
I've been keeping an eye on things since, and doing a lot of reading (mainly on her...thanks all). Next suspect was the PCV valve. It's very easy to remove, and inspect, and not a problem to open up. Simply pry the top of with two flat bladed screwdrivers. Inside, should be a spring holding a diaphragm. This should be free to move, and normally should be in the open position. Mine wasn't, it was absolutely caked in crud and carbon, stuck wide open.
The valve works by allowing some of the crankcase gases into the inlet system. In normal operation, at tickover, the valve is wide open, allowing gas to flow freely. At medium power, the valve is beginning to close, and reduces this flow. At high power, the vacuum from the inlet system sucks the diaphragm down onto its seat, closing it, and stopping the gas flow. Blowing through the valve is useless as a way of testing it, it needs to have a vacuum applied to the inlet manifold side, to "suck" the valve shut. If it isn't doing this, all the hot oil vapour from the crankcase is being vacuumed into the inlet, and burnt as fuel. No wonder he oil consumption is so high !
I have just ordered one from the local Renault dealer. They could not find the part from the part number, which was strange?
It's being fitted tomorrow, and I will update you further.
Philthy
ps, mods, I have some photos that may prove useful to attach to the post if possible?
