DPF wash out and rebuild

[poyta]

I have just bought a lovely MK5 GT diesel with only 60K on the clock and the DPF is stuffed.
Have had performed numerous forced regens and completey remove DPF and soaked in moly cleaning fluid over night worked OK for 200 klm intervals for a while and then limp mode. Approx cost so far $1300.
... anyway Greg is your squiky clean DPF still going good?

What makes you think the DPF is stuffed? Have you tried some Liqui Moly DPF cleaner? I've had fantastic success with it. Read up on my experience here http://www.vwwatercooled.com/forums/...r-87312-2.html

[Harpo]

DPF is probably OK just clogged with ash. Have soaked overnight in Liqui Moly DPF cleaner.

[ian]

Well I have the same car ,Gt diesel with 58,000 on the clock and have never experienced a Regen, ]Not to my knowledge any how]
I always drive it in a spirited manner, even though i'm retired but ive always had performance vehicles and drive them accordingly,
What would be the first sign of the DFP being clogged?

[Greg Roles]

Regens are happening Ian, every 800kms. It's when the idle raises to 1000rpm, and the car can feel a bit jerky, and induction noises rise. If you had an EGT gauge you could see it more clearly, the car does them automatically at this sort of interval even if it's not needed as a failsafe. Your DPF will start showing signs of clogging after 100,000kms typically and you will start to see DPF lights and notice regens more often as it's capacity decreases.

Yep my renewed DPF is stil going well at 165,000kms now, so it's had a further 60,000kms, I would suggest anyone with a clogged DPF look at getting it professionally flushed, liquimoly DPF cleaners only remove the soot through the Cerium catalyst, but not the ash which is the WHOLE problem, and that needs to be pressure washed back out. There are places that offer this service now.

A proper sports DPF solution will happen, but not in the short term, a lot of testing still required, and I'm not releasing anything till legally approved, so it has to meet emissions. That is unlikely to happen for the MK6 cars anytime soon if at all, but for the MKV it's looking pretty good.

[Harpo]

DPF Out!

Feeling inspired/frustrated I proceeded and after a few hours the DPF was out. Hopefully this will be quicker going back in. You need a good set of tools and it was Ok with just 2 small stands under the front. Helps to have a patient mate also to pass tools and wriggle the DPF out.



I notice that only soot came out and not ash as per Greg Roles. This could be because it was recently had Moly treatment. Greg you are right about the insulation sleeve being fragile as it feel apart after getting wet. Not to sure what to use as insulation now.

My other TDI 1.9 Golf has no DPF and only puffs a little smoke under hard acceleration and this GT has common rail so less smoke maybe? DPF in/out heads or tails.

So in hindsight when buying a second hand diesel car with DPF should use diagnostic equipment to check out clogging to avoid a time bomb OR go for GTI ( non DPF) not GT as fuel consumption and torque is improving eg MK7 GTI

Anyway feeling much better now after knocking the grap out of DPF. The big question now DPF in ( just labour)/out (>$1500 remap ECU)?

[Diesel_vert]

Could just be a dodgy exhaust pressure sensor (G450 if I recall correctly), though you might have already replaced it?

[poyta]

So in hindsight when buying a second hand diesel car with DPF should use diagnostic equipment to check out clogging to avoid a time bomb OR go for GTI ( non DPF) not GT as fuel consumption and torque is improving eg MK7 GTI

You cannot compare a GT to a GTI, two completely different cars with completely different engines. You are right though that a buyer needs to do some investigation when buying a modern Diesel as most if not all of them now have a DPF so eventually all of them will have issues for potential buyers with clogging - having said that its not like there's no issues with a modern Petrol either , the GTi has a lot of common problems for potential buyers too - the important part is that there are solutions to the problem. The washout you performed seems to have worked for Greg, the Moly treatment did wonders for me and for others a DPF delete has been highly successful but remember that a DPF delete is illegal and comes with some very heft fines if caught so if you do go down that path my suggestion is keep it to yourself and don't go posting it on the forums.

[Harpo]

G450 sensor checked by VW once and Euro specialist 4 times. VW quoted approximately $4800 for DPF replacement and install.

[Greg Roles]

OK so my DPF filled up a second time at 200 thou, and it went a lot more quickly than last time in the final stages. Whereas I had a long lead up of increasingly more numerous regens the first time, right down to every 50kms, this second time the car went from doing regens about every 100kms and suddenly tried to do three forced regens in a row ( 50 plus kms of regenning!! ) and went into proper limp.

So I did the old cut and shut a second time, in one day. It's a bitch to remove on a simple jack as you need to wriggle it around and the long tail pipe makes that difficult with limited height, but would be a piece of cake ( comparatively ) on a hoist.



I had no idea how successful this would be second time around, but unlike last time I was on a schedule ( needed the car the next day ) so I didn't bake the core in an oven to get the water out like last time. As such, despite leaving it in the sun and wrapping it in absorbant towels for a good few hours, it was likely still wet. I welded it up, banged it back in, and low and behold car was still going into bloody limp despite any form of reset.

Oh crap. I put my old G450 differential pressure sensor back in thinking that may have been it, but ended up deciding I had to limp it up to VW the next morning to try a new G450. On the way, at a very slow limp speed, it must have cleared the water, and it suddenly decided all was good, and the car reset to zero ash and has been there quite happily for 5 thou now, running like a champion. It always starts off doing regens about every 200kms, but this has been increasing up to 300kms now, as the G450 kind of relearns, so expect frequent regens for the first several or more, always seems to take a bit of time.

SO the moral of the story is if you backflush the core, make sure it is dried out properly, as this will provide the G450 with enough pressure difference to think it's still clogged, well that seems like the situation to me anyway.

[Mysticality]

... Or do a half assed job of drying it out then let it run in the back yard/around the block for awhile!

[Greg Roles]

....which if the G450 sees over 80-90% blockage will not let the car start. I dried mine out quite well ( I thought ) but it was still obviously beyond a 60% reading where the car wants to stay in limp. Slippery slope, bake it in the oven when the missus is out.

[kaanage]

Or put it on the Weber

[benough]

My GT TDI is now at 230,000km and the DPF is still behaving normally.

[Greg Roles]

You Sir are what they label an "anomoly" on a bell shaped curve. Even my Yeti running two Provents is showing towards half full of ash at 70,000kms and I'd expect it to clog about 150kms as is usual.

[jets]

My GT TDI is now at 230,000km and the DPF is still behaving normally.

That's good news for the rest of us with lower mileage cars with a DPF. Do you do a lot of highway kms?