Dmax issues where do I stand?

[Woodworks]

Andy. What do you recon to "Disgruntled Dmax owners" for the Facebook group name?

[Woodworks]

Sounds like the well documented problem to do with ACTIVE DPF regen in Euro 5/6 vehicles. Seems to affect some vehicles more than others. From what I have been reading the excess injected fuel (intentionally injected to cause REGEN) leaks past the rings, as expected, and dilutes the oil. You will need to change the engine oil PDQ otherwise it leads to engine problems. Sounds like you have a DPF issue... But then you knew that already:thumbdown:

 

Sorry GreenGui.

 

Re reading this thread and don't know how I overlooked your post.

Apologies

[TimberCutterDartmoor]

Woodworks: nothing like as bad as gasoline dilution but bad all the same. Gasoil does not hold up MOFT in bearings or cams. I will go and unearth my old idgte lecture notes

 

Reduced viscosity, flashpoint, etc.

 

Excess of 2% is considered severe.

Edited November 1, 2016 by TimberCutterDartmoor

[kevinjohnsonmbe]

Andy. What do you recon to "Disgruntled Dmax owners" for the Facebook group name?

 

People power!

 

If you had 'sister' pages:

 

"disgruntled R.... Y.... ex customers"

 

And

 

"disgruntled waiting for Toyota delivery customers...."

 

I'd be in both!!

[TimberCutterDartmoor]

My "100,000" miles posted earlier was conservative!

 

Over that 2% will reduce lifespan from 75000 to 30000, or 750000 to 300000 and so on.

 

Sorry.

[GreenGui]

Sorry GreenGui.

 

Re reading this thread and don't know how I overlooked your post.

Apologies

 

No Worries - some people talk louder then others on here

 

My research on Subaru diesels indicated that Subaru work to a 10% oil dilution ratio. At this point if active regens are still occurring and this percentage has been reached the DPF light comes on, limp mode and a mandatory trip to the dealers... The ratio is based on counting the number of active regens so by implication they know exactly how much oil slips past the rings on each regen event.

Edited November 1, 2016 by GreenGui
incorrect percentage quoted

[openspaceman]

Thinking over this thread, and not having a car with a DPF, may I give my summary of what seems to happen, feel free to correct what I have wrong.

 

The problem only seems to affect some Dmaxs, Isuzu put it down to the wrong sort of journey.

 

The DPF is a series of very small blind holes in a ceramic filter medium, the gases pass into the these tubes then through the walls, carbon and ash particles being trapped in the walls of the tubes.

 

There is a pressure sensor in the DPF housing that senses when the tubes are getting blocked at which point it enters a regeneration cycle.

 

Is there any indication this regeneration cycle is occurring?

 

If the DPF is too cold the ECU squirts an amount of fuel into the engine just before the exhaust valve opens, presumably this carries on to the DPF as a flame and heats the ceramic matrix to burn off carbon in the excess air diesel exhaust inevitably have.

 

The ash stays in the DPF and eventually kills it. This is why a low ash oil must be used in engines equipped with DPF.

 

As the DPF regenerating injection happens so late in the cycle certain components of the fuel, thought to be derived from the BIOdiesel content, coalesce on the cylinder wall and eventually run into the sump, increasing the oil level and diluting the lubrication oil.

 

From my experience with diesels without DPF one of the chief reasons for excess soot is a leaky EGR valve.

 

My other experience with a Pug 206 1.4TDCI engine which does have a sort of filter is that it is easily accessible and can be unblocked with a blow torch. I suspect much the same could be done with a modern DPF but the air flow must be reversed because of the blind holes, anyone have experience?

 

I would choose to use an electric hot air gun.

 

So apart from breaking up the filter and fooling the pressure sensor the solution appears to be to keep the DPF free flowing enough so that it never goes into an active DPF cleaning routine.

[swinny]

OK I have been suckered into hanging onto this truck for a bit longer but the end is near. Dealer was very helpful and reassuring after it's last check over and persuaded me into hanging onto it. Since the last service and oil change had hoped the problems would be better as during the summer and autumn been clocking up more miles on longer trips so no problems with interrupted regen cycles. Problems have been worse than ever . In 4000 miles the oil has gone from normal to max. Just had to drain some out to avoid overun. Drained out 1 litre of very thin oil/diesel mix and it's only brought the level down a bit. Seems it has gone up by at least 2 litres when it would have only had 7.5 litres of to start with.

 

Before and after pics from draining a litre of "oil" from the sump. The level should be between the yellow markers.

 

 

You see to me that oil is way to high.

 

Should be between the dots between the yellow tube guides i say could be a serious percentage of diesel there bet up to 40% above correct level so maybe 2.5-3 ltrs too much

[GreenGui]

Thinking over this thread, and not having a car with a DPF, may I give my summary of what seems to happen, feel free to correct what I have wrong.

 

The problem only seems to affect some Dmaxs, Isuzu put it down to the wrong sort of journey.

 

The DPF is a series of very small blind holes in a ceramic filter medium, the gases pass into the these tubes then through the walls, carbon and ash particles being trapped in the walls of the tubes.

 

There is a pressure sensor in the DPF housing that senses when the tubes are getting blocked at which point it enters a regeneration cycle.

 

Is there any indication this regeneration cycle is occurring?

 

If the DPF is too cold the ECU squirts an amount of fuel into the engine just before the exhaust valve opens, presumably this carries on to the DPF as a flame and heats the ceramic matrix to burn off carbon in the excess air diesel exhaust inevitably have.

 

The ash stays in the DPF and eventually kills it. This is why a low ash oil must be used in engines equipped with DPF.

 

As the DPF regenerating injection happens so late in the cycle certain components of the fuel, thought to be derived from the BIOdiesel content, coalesce on the cylinder wall and eventually run into the sump, increasing the oil level and diluting the lubrication oil.

 

From my experience with diesels without DPF one of the chief reasons for excess soot is a leaky EGR valve.

 

My other experience with a Pug 206 1.4TDCI engine which does have a sort of filter is that it is easily accessible and can be unblocked with a blow torch. I suspect much the same could be done with a modern DPF but the air flow must be reversed because of the blind holes, anyone have experience?

 

I would choose to use an electric hot air gun.

 

So apart from breaking up the filter and fooling the pressure sensor the solution appears to be to keep the DPF free flowing enough so that it never goes into an active DPF cleaning routine.

 

The problem exists on all diesels (to a lesser or greater extent) with an active regen cycle that relies on post ignition secondary injection. The technology works fine on things like trucks (indeed thats where it originates from) that spend all day on a motorway and maintain a very high DPF and oil temp but on smaller vehicles doing short trips the DPF never warms up so the active regens fails and cause a vicious cycle. The theory goes that excess diesel should evaporate off (diesel boiling point 190 deg approx.) in the hot sump oil and in a truck, yes. But short trips and cold oil it just sits there and builds up in the sump of smaller passenger vehicle engines.

 

The fix on the latest generation small diesels is to put an injector directly into the DPF and do away with the post ignition injection on the main injectors.

 

Several companies now claim to be able to clean the DPF, it requires more than just a hot air gun unfortunately.

 

The manufacturer stating this is an acceptable state of a fairs makes a mockery of all the manufacturer requirements for fancy (expensive) oil specs IMO.

[openspaceman]

 

The fix on the latest generation small diesels is to put an injector directly into the DPF and do away with the post ignition injection on the main injectors.

 

Yes this was pointed out earlier in the thread but not much use to someone with the problem on a vehicle now without a completely new program for the ecu.

 

 

 

Several companies now claim to be able to clean the DPF, it requires more than just a hot air gun unfortunately.

 

 

Yes I see there are chemicals which can be put in via the pressure sensor but the nature of the thing makes me think it really needs to be a reverse flow, I'd not like the problem but would like to try it if I did.