Originally Posted by Nickthecook
Many have either sold or scrapped their Euro4 D5 after hitting a dead end in trying to resolve this problem. Firstly, if you're using the recommended 0w-30 A5/B5 and you're burning oil, theres a good chance your CAT is poisoned with Phosphors. This engine oil is not CAT and DPF friendly. But frst we need to understand why the Engine is consuming so much oil. I've read 100's of posts on various sites about D5 DPF's getting repeatedly blocked and the oil consumption as a result of almost continuous regenerations. Regenerations that never actually seem to clear the DPF. Many believe, because they've been told, that the oil burning is as a result of engine damage from bore wash. Bore wash can occur when a regeneration is interupted and diesel left in the cylinders can wash down the side of the pistons into the sump. They hypothesize that this causes wear and that gases are now blowing by the pistons, creating excessive crankcase pressure that forces oil through the breather into the induction system. This oil produces high levels of ash, due to the level of SAPS contained in it. Odd how every bit if information out there regarding OIL, CATs and DPF's, states that only a C grade should be used, as other grades will irreversibly damage the Catalyst and block the DPF and reduce it's lifespan. Ash can't be burned off like soot, it can only be physically cleared out. I agree in part with this, in that it is excessive crank case pressure that is responsible for the oil consumption. I don't however think it's being caused from blow by, at least not in all cases. After all, blow by isn't selective about when it choses to happen. This high oil consumption only occurs during regenerations and increases inline with the frequency of them. So what's different about a regeneration that could cause excessive crank case pressure? On the D5's fitted with the M66 box, is an EGR Cooler Bypass Valve. This valve is only in operation during engine warm up and Active Regenerations. It's purpose is to allow uncooled EGR gases back into the system to reduce engine warm up times and to help lift the exhaust gas temperatures during a regen. This valve is electronically controlled, but is physically opened by a Vacuum Actuator. (Volvo calls it a Vacuum Box) If this actuator is leaking badly and the valve fails to open, a) more soot produced as a result of slower engine warm up. b) an integral part of the regeneration process won't be working and as a result regeneration gases won't get as hot. c.) You won't get any warning or code as the actuator isn't monitored by the ECM. d) This is the bit that I 'THINK' is causing the oil problem. The Vacuum pump is going flat out trying to pull a Vacuum on the leaking actuator and the Vacuum pump vents Into the top of the Engine to be fed through the breather system. I've searched many diesel forums and discovered that Vacuum Pumps that vent this way can lift crank case pressures sufficiently for the car to start burning oil. One guys exhaust stopped smoking within a minute or so of him clamping a leaking vacuum hose. When I replaced the lifters on mine, the metal breather pipe that runs over the top of the rocker cover, was full of oil. My D5 has covered 226k, it ticks over 1rpm or 2 rpm either side of 700rpm. It certainly isnt lacking any power and at idle there is absolutely no sign that I have blow by or excess gas/pressure. When the engine is cold or in regeneration, there is however the tell tale glug,glug,glug noise from the oil filler. A sure sign of a vacuum leak. Some of you may have noticed this noise when you've had a leaking engine mount. Imagine it at 2,200rpm with the oil filler cap on. I may be barking up the wrong tree, but there doesn't seem to be any inbetween. There's Euro4's that don't use a drop of oil and those that drink it by the bucket. I'm going to clamp off the line to the EGR Cooler Bypass valve and monitor the oil consumption. I'm also going to look into whether the engine could run on a C grade oil, with more frequent changes. If you're currently having similar problems with a Euro4, or have experienced them in the past, I'd love to hear your comments. I know it seems like a long shot, but logically it is possible. I will certainly know either way within a couple of weeks.
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