Oil Consumption & Soot Filter Full - THE TRUTH
 

Mention the issue surrounding the Euro IV D5 (D5244T4) and stupidly high oil consumption and everyone shouts back 'Seized Oil Rings.' Well now you can shout back, 'Wrong Sucka.'

Maybe a little oil is getting past the rings, but the majority of it is actually being sucked from the engine. It took some working out and my head really hurts now. Ok, here goes......

Your oil is being pulled from the crankcase breather pipe where it enters the air intake, next to the turbo inlet. You see, the Euro IV uses what is known as an HPL EGR system, albeit a very poorly designed one. HPL stands for high pressure loop. Unfortunately, Volvo messed it up by

a) using a Pressure Only MAP Sensor (it bottoms out just below atmospheric pressure and therefore doesn't show if there's a Vacuum Present) But Diesels work with excess air? That's not strictly true of the Euro4, I'm afraid.

b) They put the MAP Sensor on the intercooler, when it should have been placed the other side of the EGR/Throttle body. Ever wonder why the hole's not been cut for the sensor on a new intercooler? Now you do.

c) Poor control systems in general, with no safety net. As one article stated, 'Using two separate closed control systems for the EGR Flow and the Turbo Control, risks serious consequences without adequate oversight.' HPL EGR was already 2-3 years old by the time the Euro IV was released, so I'm not sure why Volvo made such a mess of it.

The HPL system works by utilizing the VNT Vanes and throttle to alter air flow and create a Pressure differential between the fresh air going in and the Exhaust gases coming out. Done correctly, a high flow of EGR is drawn through to the intake side. Not done correctly, a Big Vacuum is created in the intake, which sucks open the CCV Valve, on the exhaust side you see the opposite occur in the form of high pressure exhaust gases, which causes the DPF pressure sensor to spit it's dummy out.

This isn't just a theory, I have diagnostic data to back it up. Basically, when pulling away after slowing down and using the engine to brake, I was billowing smoke out of the back. Not so much D5, as Bonds DB5 with the smoke screen switched on. This just didn't fit in with the 'Oil Ring' issue everyone said it had. VIDA of course didn't show the Vacuum, only the MAP sensor bottoming out. So I used Torque and set it to calculate boost with the MAF Data instead. My fist thoughts were.....WTF? A 16.2hg vacuum in a Diesel Intake, this can't be right, but then I remembered the reason I'd decided to use the MAF sensor, it was because the MAP value had suddenly dropped and bottomed out. Then I looked at the Air Intake Temp and saw a sudden, sharp drop in temperature. This of course fits with the sudden drop in pressure.

Now for the other side. I've recently purchased 2 x (non Volvo, but not cheap) Differential Pressure Sensors. Despite being the correct part, neither will adapt to within the specified parameters. I can only assume Volvo's attempt to rectiftly their design **** up through a software patch (DPF/Oil Level) changed the original specified values for the sensor. Worryingly, the old sensor never threw a code but the engine felt like it had reached the end of it's days. However, in between the relentless DTC's generated by the new sensor, The car was an altogether different beast. Smooth, quiet, responsive and **** me it's got some power back.

With regard to the 'Soot Filter Full' messages, I'm more likely at present to get the message during lift off, than under boost. Lifting off/ engine breaking, seems to very quickly turn 20psi boost, into a -10psi vacuum on the intake, this of course means a spoke in pressure exhaust side. As an after thought, the DPF system on the D5 has to be able to cope with the increased speed and pressure of the exhaust gases, generates by the HPL EGR system. This is probably another reason the original part doesn't adapt, as the other vehicles it also fits do not have this system.

As I've only just got to the bottom of this problem, I don't as yet have a solution. But I would suggest a new CCV Valve a good place to start. Followed by an EGR overhaul and a Turbo control overhaul. Then there's The DPF, which seems to play a major role in the problem, as the more restriction there is, the worse the intake/exhaust pressure differential becomes.

I would imagine the so called 'rising oil levels as a result of bore wash' was more than likely a vacuum in the crankcase, sucking the diesel past the rings.

Finally, I find it extremely hard to believe Volvo were unaware of their design error, so I may just contact them to ask why they let so many loyal owners waste their money, trying to resolve a problem they didn't understand. I even know of owners who have sold/scrapped their Pride and Joy, rather than waste anymore money. One poor Guy even said to me, 'I'm certain it has something to do with a Vacuum.' Volvo, you're utter B******S for keeping this one to yourselves.'

So there you go, finally the truth as to why some Euro IV's consume oil nearly as quickly as they do diesel. When I get a minute, I'll post some screen shots of my diagnostics to back up the above. But in the meantime, if you have one if these problem cars, try calculating boost via the MAF and see what figures you get. Rapid engine braking seemed to produce the biggest intake vacuum, although a long downhill section of road could draw a huge volume of oil from the crankcase. Please let me know how you get on, both with testing for the problem and also any fixes you may have found.

Mine is one of the XC90s that went for scrap...

I don't believe the theory I'm afraid, I ran the following test.

Crank case breather hose cut in half, the inlet manifold end blanked off, the other end run to a bottle but left open to atmosphere.

I still found that after engine braking I was bellowing big clouds of blue, oily smoke. It couldn't possible be being sucked out of the engine as that pipe was in a bottle, open to atmosphere.

I'm still convinced it was stuck/blocked/worn piston rings.

I've replaced the CCV and looking at the design of it, it gets sucked closed if there is too much vacuum from the intake and. So if the CCV valve is working correctly this theory should not be an issue.

My new valve made no difference to my oil consumption.

I also tried the blanking off the intake pipe and routing the CCV to a catch canister, but oil consumption was just as bad....

I'm working on another idea that I've carried out on my car but its too early to see if oil consumption has been affected

I'm starting to think I drive a different car to you guys. How did you manage to cut a fully water jacketed pipe in half? And again, the CCV Pipe itself, which is 9nly viabke for about 2-3 inches either end of it coolant containing jacket, is rock hard. With the greatest respect, Is it possible you've both mistaken the rocker breather to oil separator pipe for the CCV Pipe which is part rubber, part metal and has a water jacket running from where it exits the separator, upto about 2 inches before it enters the hard plastic MAF to Turbo pipe, just before it joins the Turbo. If not, your vehicles are of a different design to my '06 V70 D5 D5244T4.

Where ever the oil is being sucked from and I don't deny that it might be getting pulled past the side of the pistons on their intake stroke, it is without doubt caused by the combination of excessive exhaust back pressure and substancial intake vacuum, resulting from a badly thought out 'High Pressure Loop' EGR.

There are undoubtedly other factors that may be contributing to the problem, such as a blocked EGR cooler, or a split diaphragm within the EGR Cooler Bypass Valve, which will not only prolong warm up, but the Vac pump will be working flat out as a result of the broken actuator. This will increase the temperature of the engine oil and as the Vac Pump vents through its oil supply from the exhaust camshaft, it will also pump a significant amount of fresh air into the rocker. This definitely is a contributing factor 8n CC Pressure, because I've tested it with and without a leak. With, resulted in blue exhaust smoke, without a leak it was clear.

I disconnected the breather pipe from the turbo inlet and the spigot from the valve. I left the alu pipe in place with the both ends free to air and coolant side of it unaffected.

I fitted a small piece of hose with a bung in it to cap off the turbo inlet pipe and then a long piece of hose straight from the CCV valve spigot into a catch tank.

Oil consumption like this was just as bad and no oil was collected into the catch tank.

Its still early days but I seem to have fixed my oil consumption issue at long last.

I've been reading all the posts I could on D5 oil consumption and tried the cheap fixes with no luck. I was very reluctant to strip the engine and fit new rings or valve stem seals and or fit a new turbo as someone had oil consumption even after all that!

It wasn't until I read someone said that you can check when the car is doing a dpf regen by watching what the EGR is set to. They said it sits at 94.9% while the regen is taking place.

I do mostly motorway miles so with an OBD2 reader and the torque app on my phone I discovered my car was going into a regen as soon as it was up to temperature and it did this for 20 mins. The egr valve would then start moving about depending on throttle position suggesting regen had finished.

But not more than 20 to 30 seconds later the EGR went to 94.9% again and another 20min regen!

this would explain why I never saw the fuel economy drop when trying to work out when it was in regen before because its been in constant regen for thousands of miles!

I worked out in the 8000 miles ive been having fuel consumption and oil consumption issues the dpf has tried to regen around 400 times when it should have been 10 to 16 times!

not once have I had a DPF full light on thought!

I think there is a fault with Volvo's DPF regen stratergy when the DPF is full of ash and needs cleaning or replacing (no amount of regens will burn off ash). There is no counter between regens to flag if there is a problem that the regens are happening too frequently.

I think there are a lot of d5 out there this is happening to and the oil is being diluted with diesel lowering its viscosity and increasing oil consumption.

Also I think the backpressure could be causing oil loss through the turbo seals.

I have removed the blocked dpf from my car and it wasn't full of soot but solid with light colour dust (ash?) but the downpipe to the dpf was in a horrible state, full of black wet diesel soaked soot.

a new unblocked DPF and there is now no measurable oil consumption so far!
and this is with the soot filter full light never coming on!

Unbelievable, I'm in complete shock. I've fixed it, because the whole bloody thing is caused by a short on the Throttle body connector plug. No DTC, throttle works, it adapts with VIDA, it clicks when activated, but it closes when you put your foot down. Result, air starvation and a vacuum string eno7gh to suck the engine oil past the rings. Yes, had Volvo put the bloody MAP sensor where they were supposed to, this would have been picked up immediately. I am trully stunned and still haven't stopped swearing.

Do not confuse the EGR and Throttle body. The EGR is the big unit with the right hand hose connecting to the top of the intercooler and the left side hose going into the inlet manifold. The butterfly valve you can see if you take the pipes off and look through the hole, is the Throttle valve and not the EGR as some think. There's a video on you tube titled 'Cleaning the EGR on a Euro IV D5, however the guy's actually cleaning the throttle valve (bolted to the right hand side of the EGR unit,) The EGR is not a Butterfly Design on the Euro IV and cannot really be viewed, but if you look through the EGR, you will see an opening on the bulkhead side of the Throttle valve, that's where the EGR gases enter from the EGR Cooler. If you stand at the from of the car and look at the EGR, to the right and below it, Is an oval black plastic cover with metal clips on the side. Underneath this is the connector plug for the Throttle.

how did you find and fix it?

with the throttle closing it must have been way down on power!

so your car is now no longer using oil? awesome result

surely with the throttle closing the car would have been nearly un-driveable?

I know when mine was consuming oil it still had bags of power

2007 d5 oil consumption 1l/2000km
1. new egr
2. rebuild turbo
3. new throttle body -the car went in safe mode when it broke so can not say if the car
is nearly un-driveable while throttle closed
4. new valve, Crankcase breather
5. dpf off

Result -oil consumption higher

Nickthecook - what do you mean with short on the Throttle body connector plug? Would not a new Throttle body resolve that?

Next - new oil rings. If that resolves oil issue i will let you know.