Sticking VNT's and AR6400D

[Avalon]

Following on from my experiences with BG244 Here i've started to notice the same issue as previously. Short version is the turbo is mechanically fine as far as I can tell from the compressor wheel side, no play and most days it's fine (108k and counting), but occasionally the control ring that alters the angle of the vanes doesn't move freely due to carbon build up and you can be sat waiting for the turbo to spool followed by a surge when it kicks in, this is usually obvious going up a hill accelerating to join a motorway etc. but more recently it's been happening in other situations. This is not what you want to happen when overtaking or going up hill etc. I don't help this situation as the majority of my driving is short runs year round with the majority of the distance driving being March to December at weekends. The ultimate fix is to strip the turbo and clean the control ring set-up and then re-install the turbo. Thing is that's not the easiest of jobs (11 years and 100k+ of heat cycles will make that a fun job when it's required) and the same issue will come back eventually due to the way the combustion process works, but it should be in another xx thousand miles.

Knowing my usage pattern and 'local' fuel options I made the switch to Millers Eco Boost, which 'should' allow for a cleaner and more complete burn and less deposit build up. It's not going to work miracles but the EGR is still nice and clean and it allows me to run 'normal' grades of fuel most of the benefits of premium fuel even if I get caught having to fill up with supermarket fuel. It works out at £12 to treat 10 tanks of fuel, that's compared to £50+ for BP Ultimate/Shell Nitro over 10 tanks.

I have three options when it comes to cleaning the turbo

1. Fuel additive eg Forte Turbo cleaner or AR6400D.

2. Sodium Hydroxide foam directed into the control ring area using a tube eg oven cleaner such as Mr Muscle.

3. Aerosol based cleaner eg Wynns Turbo cleaner or Revive

Forte is reasonably well thought of in the trade, AR6400D seems to get positive reviews from the public. The Mr Muscle approach is well thought of in VW forums and well proven. Wynn's is a simple idea, but I can't see it making a massive difference, Revive has a decent background, but it's quite a priceyhave mixed reviews, but again it's largely down to what the issue is/was. All of the options run from about £1 (no name oven cleaner) to £20, so non of them are expensive. I decided to take the holistic approach, i've added AR6400D and will then treat with an aerosol cleaner followed by sodium hydroxide if required.

Day 1: Full tank of BP Regular and a bottle of AR6400D added to the tank.

First 200 miles the only difference is the engine noise is slightly smoother, with the cold weather i'm only expecting 370-400 miles out of a tank, but that should take 2 weeks to hit, so plenty of time to soak. I've also made a point of using the higher end of the rev range on occasions.

More updates to follow.

[cobh18]

You might find the VW site reference that follows to be useful: http://forums.tdiclub.com/showthread.php?p=1340914

Point made that the binding of the actuator requires removal of soot internal to the VNT, for cleaning to be effective. Of course, Toyota may use a different method but I guess there is some similarity.

[Mark O]

I had sticking vanes with a Golf TDI turbo. I tried the Mr Muscle treatment as per the link above and as the alternative was mega bucks for fitting a new turbo or a rebuild. In my case unfortunately it didn't work and I subsequently sold the car, but given the alternatives it is well worth a try and there is nothing to lose. Many folk of the TDI forum profess to have had success though. Actuate the vanes manually when soaking to try and free them up. 

Don;t forget it may not be the turbo that is at fault. If solenoid actuated, check these out first - particularly the boost solenoid.

[Avalon]

On 2/10/2017 at 3:24 PM, cobh18 said:

You might find the VW site reference that follows to be useful: http://forums.tdiclub.com/showthread.php?p=1340914

Point made that the binding of the actuator requires removal of soot internal to the VNT, for cleaning to be effective. Of course, Toyota may use a different method but I guess there is some similarity.

I'm on my 4th high mile VW PD engine (Current Altea is at 160k) so have done my fair share of EGR/manifold/Turbo cleaning. I got chicken nugget size chunks of gunk out of the Altea last month, nothing like the fine soot build up on the D4D's EGR. The ideal method as the PDF states is to strip it, crack the housing, remove the control ring and VNT assembly, chemically clean then ultrasonically clean the parts, then put it all back together replacing the oil pipe and remembering to draw oil to the turbo rather than run it dry. I don't mind doing it and if i'm honest it's the route i'll eventually take, but if I can find a solution that's effective in solving it without dismantling that's worth sharing.

On 2/10/2017 at 7:02 PM, Mark O said:

I had sticking vanes with a Golf TDI turbo. I tried the Mr Muscle treatment as per the link above and as the alternative was mega bucks for fitting a new turbo or a rebuild. In my case unfortunately it didn't work and I subsequently sold the car, but given the alternatives it is well worth a try and there is nothing to lose. Many folk of the TDI forum profess to have had success though. Actuate the vanes manually when soaking to try and free them up. 

Don;t forget it may not be the turbo that is at fault. If solenoid actuated, check these out first - particularly the boost solenoid.

Good point, it could be vac pipe or solenoid related, thing is it's fine any time i'm not going up hill and accelerating in a manner that requires the VNT system to go from full open to full closed, i'll check the solenoid function.

So how did the AR6400D do? Well after 300 miles things haven't changed much/may be marginally better? I can still reproduce the fault when going up an incline, eg running to a higher point in the rev range (VV open wide) and changing up to the next gear (VV required to switch back to closed position), this continued till the full tank had been used. The weather is also warmer now so this could have some minimal effect.

Next up I chucked £20 of BP Ultimate (14p a ltr extra!) in and a full dose of Millers Eco Boost, same as before, it's no worse and no better. This morning I filled up with a full tank of Jet and added Millers again. Next up it's looking like the Wynn's aerosol and see what that can do, in theory it's just expensive solvent. My gut feeling is Mr Muscle is the only thing I can see making a difference which is why i'll leave it till last.

[FROSTYBALLS]

Could try Cillit Bang. At Sellafield they saved £ hundreds in both time and money using Cillit Bang to clean plutonium stains as it was more effective than a specialist cleaner they had been using - http://www.telegraph.co.uk/finance/newsbysector/energy/6078265/Nuclear-experts-clean-radioactive-site-with-Cillit-Bang.html

[fordulike]

5 hours ago, Avalon said:

I'm on my 4th high mile VW PD engine (Current Altea is at 160k) so have done my fair share of EGR/manifold/Turbo cleaning. I got chicken nugget size chunks of gunk out of the Altea last month, nothing like the fine soot build up on the D4D's EGR. The ideal method as the PDF states is to strip it, crack the housing, remove the control ring and VNT assembly, chemically clean then ultrasonically clean the parts, then put it all back together replacing the oil pipe and remembering to draw oil to the turbo rather than run it dry. I don't mind doing it and if i'm honest it's the route i'll eventually take, but if I can find a solution that's effective in solving it without dismantling that's worth sharing.

Good point, it could be vac pipe or solenoid related, thing is it's fine any time i'm not going up hill and accelerating in a manner that requires the VNT system to go from full open to full closed, i'll check the solenoid function.

So how did the AR6400D do? Well after 300 miles things haven't changed much/may be marginally better? I can still reproduce the fault when going up an incline, eg running to a higher point in the rev range (VV open wide) and changing up to the next gear (VV required to switch back to closed position), this continued till the full tank had been used. The weather is also warmer now so this could have some minimal effect.

Next up I chucked £20 of BP Ultimate (14p a ltr extra!) in and a full does of Millers Eco Boost, same as before, it's no worse and no better. This morning I filled up with a full tank of Jet and added Millers again. Next up it's looking like the Wynn's aerosol and see what that can do, in theory it's just expensive solvent. My gut feeling is Mr Muscle is the only thing I can see making a difference which is why i'll leave it till last.

I used to own a Nissan Almera DCi with a VNT controlled turbo. Terrible for getting gunked up every now and again. I used the Wynn's stuff as recommended on www.mafcleaning.co.uk, which seemed to keep the troubles at bay. Mind you, I did drive it like I stole it, after running the stuff through, and the amount of black crud blowing out the exhaust was unbelievable 

[Mark O]

I never have too much faith in the in-tank cleaners. I simply cannot see what use remains after it has been through the engine and undergone combustion. I would agree that stripping the turbo and cleaning is a far more effective method, but reading around previously I did note some folk had success with injecting Mr Muscle or similar - which is why I tried it! I guess it's worth a try as the stripping turbos is usually quite a job and becomes pricey if you are paying for the labour.   

Do check solenoids, and don't assume they work just because they check out electrically. They can and do stick. Check any vac/air hoses also.

[fordulike]

The Wynns EGR3 stuff goes through the air intake, but again, debatable how much actually gets on the right parts. Any form of preventive maintenance can't be bad though, rather than none.

[Mark O]

It isn't preventative maintenance if it doesn't prevent maintenance. All it may do - and I stress may - is put the inevitable proper solution off a little longer. Even the Mr Muscle trick is a bit of a sticking plaster remedy, prolonging the inevitable proper clean or replacement. I concede that they may prolong the inevitable for enough time to either flog the car, pass an emissions test, or for time to pass until you have the readies to do the job properly, but there is no substitute for the latter. 

[Avalon]

All turbo's are subject to carbon buildup by the very nature of how they function, any solution including replacement is therefore just a temporary measure to a greater or lesser extent. You could argue replacement should give the best long term outlook at the highest cost, personally i'd rather just strip/clean it if it comes down to it and the turbo is otherwise servicable. I'm lucky/daft enough to be able to do my own work so the only cost is consumables, a new oil feed/fitting kit (unless you're really tight) can't be that bad from Mr T surely? In an ideal world it should be part of the service schedule along with an EGR strip/clean.

This thread was more a case of looking for a solution that may be effective as part of routine servicing to reduce the carbon build up, i've got to the stage where I have an issue that I can replicate in testing and give some insight into what works and what doesn't assuming i've diagnosed the issue correctly. Realistically the only product I expect to make any real difference (if any of them do) is sodium hydroxide, but it's not the nicest of things to use and it doesn't get on well with aluminium or skin/eyes. Some of the cleaning agents have been shown to survive the combustion process, that said to what benefit is debatable. In theory 2-EHN added to fuel improves combustion which should mean less carbon and potentially carbon scarification, is any of this going to unblock a control ring? Not from my testing so far. Ideally i'd strip the turbo before and after each treatment and weigh it to show what if any reduction in carbon each treatment had yielded, that kind of defeats the point of what i'm trying to do though :D

[Mark O]

To consider replacement of the turbo a temporary measure is something of a reductio ad absurdum. Is the entire car thus a temporary measure until a replacement car is purchased? A replacement part - especially like for like - is more accurately considered to be returning the car to original specification, which presents the best - in engineering terms at least - solution to your problem.

If you are able to strip the turbo and clean it out, then I  would argue that comes a close second to a replacement part in terms of best engineering practice, but probably first in terms of presenting the best overall solution for you - considering the cost of the replacement turbo and your free labour.   

Purely in terms of best engineering practice, in-tank cleaning agents IMHO are last, Mr Muscle applied via a hose to the turbo third - as even if it does work, the time before failure is very likely to be shorter than the first and second methods. However, for those who have to pay to have the turbo to be stripped and cleaned, it may offer the best solution provided it works albeit perhaps temporarily - as one has to factor in the labour costs of the strip and clean.     

if looking to reduce carbon build up in future my advice would be to use decent fuel, try and run the car at optimum revs, use a decent low ash oil, and don't switch off immediately after a long run - allowing the turbo to cool by idling for a couple of minutes.  

Edited February 17, 2017 by Mark O
accuracy

[IanML]

21 hours ago, Mark O said:

To consider replacement of the turbo a temporary measure is something of a reductio ad absurdum. Is the entire car thus a temporary measure until a replacement car is purchased? A replacement part - especially like for like - is more accurately considered to be returning the car to original specification, which presents the best - in engineering terms at least - solution to your problem.

One could argue that the very best engineering solution is to replace the vehicle with a normally-aspirated petrol-engined version, thus avoiding a recurrence of the problem.  Doesn't help the OP, I know, but I am struck by the preponderance of problems due to the diesel engine on this forum.

[Mark O]

There is no intrinsic problem with the diesel engine. It is more efficient than a petrol engine by some degree, is not reliant on any separate ignition system and thus far simpler, and is generally far more robust. What kills it is are the ill-thought out pollution control measures introduced over the years by our dear friends in Brussels - particularly EGR and DPF - both of which have spurious benefits, and to an extent, the addition of turbos - which for most of the time are unnecessary. 

 

[IanML]

I agree with all of that.  I used to drive a diesel Land Rover 50 years ago, and it was absolutely superb.  That's why I said "on this forum" - unfortunately the diesels of yesteryear are not available in RAV4s.

[FROSTYBALLS]

9 hours ago, IanML said:

I am struck by the preponderance of problems due to the diesel engine on this forum.

Then again people only tend to post on a forum when they require help with a particular issue - be it petrol or diesel. One doesn't hear from the owners who don't have issues and who probably far outnumber those who do.

If diesels, and petrols, from yesteryear were in today's cars, pollution would be much worse.

[Mark O]

Moot point perhaps but the term "engine" does not normally include the DPF and EGR nonsense - which is why i said what I said! I concede that it normally includes the turbo though. Agreed that older diesels were the way to go. It is a great pity that such an efficient, robust and economical ICE has been strangulated by so much ill-considered opinion.    

[Mark O]

1 minute ago, FROSTYBALLS said:

 

9 hours ago, IanML said:

I am struck by the preponderance of problems due to the diesel engine on this forum.

Then again people only tend to post on a forum when they require help with a particular issue - be it petrol or diesel. One doesn't hear from the owners who don't have issues and who probably far outnumber those who do.

If diesels, and petrols, from yesteryear were in today's cars, pollution would be much worse.

 

Not hearing from owners is not helpful. We don't know if they have problems or not. What we do know, is that on the forums, there does tend to be a disproportionately large number of issues with diesel cars - particularly with the ancillary components of the engine which in turn suggests there is an intrinsic issue - which there is.

I think the yesteryear comment was perhaps in reference to the reliability of the engine without the troublesome ancillaries rather than a comment about pollution. Today's diesel, even without these ancillaries, is far cleaner than yesteryear's diesel and it is debatable whether EGR and perhaps even DPF are truly effective in combating emissions.

[FROSTYBALLS]

My comment is still valid - people tend to post when problems occur and they're seeking a solution.

[Mark O]

 I wasn't questioning the validity of it, I was questioning why it seemed to be posed as an argument against the comment that there is a preponderance of problems on this forum with diesels.

[FROSTYBALLS]

It wasn't posted as an argument against anything, it was a statement of fact.

[Heidfirst]

8 hours ago, Mark O said:

 there is a preponderance of problems on this forum with diesels.

I suspect that the majority of RAV4s sold (at least in the last 10 years) in the UK are diesel & probably a good % of those are being driven in cycles that are not good for/suited to modern common rail turbo diesels. These are also fitted with extra bits (turbo, intercooler, DPF) etc, that can go wrong over a conventional normally aspirated petrol. If you were to analyse the posts I again surmise that the majority of problems are to do with these additional parts. This is not an issue unique to Toyota - the simple, bomb-proof diesels of old are no more (at least in Europe).

Additionally, those RAV diesels fitted with AD series engines built within the problematic period that may suffer from head/head gasket issues due to an inherent problem (same as the 1.8 VVTi petrol pre mid-2005 could suffer from high oil consumption due to an inherent issue) which is a Toyota-specific issue.

[IanML]

7 hours ago, FROSTYBALLS said:

It wasn't posted as an argument against anything, it was a statement of fact.

The phrase "Then again" usually introduces a counter-point, I think 

[IanML]

9 minutes ago, Heidfirst said:

I suspect that the majority of RAV4s sold (at least in the last 10 years) in the UK are diesel & probably a good % of those are being driven in cycles that are not good for/suited to modern common rail turbo diesels. These are also fitted with extra bits (turbo, intercooler, DPF) etc, that can go wrong over a conventional normally aspirated petrol. If you were to analyse the posts I again surmise that the majority of problems are to do with these additional parts. This is not an issue unique to Toyota - the simple, bomb-proof diesels of old are no more (at least in Europe).

How true, you need only look at the Peugeot forums.  My reaction to the prospect of a modern diesel is a well-known phrase embodying "touch" and "bargepole"

[FROSTYBALLS]

15 minutes ago, IanML said:

The phrase "Then again" usually introduces a counter-point, I think 

Which is a contrast and not an argument.

[Heidfirst]

1 hour ago, IanML said:

 My reaction to the prospect of a modern diesel is a well-known phrase embodying "touch" and "bargepole"

It depends upon your usage. For high milers doing lots of motorway work, properly maintained (& ideally under warranty) they are great & will return better mpg than a hybrid, for people doing 1 mile to the shops & back they are a disaster waiting to happen.