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Discussion Starter #1
Mine has passed over, and the garage is quoting around £800. The part is £300, and incredibly labour intense. The prop shaft has to come out For a start. They tell me it takes 8 hours.
Any views appreciated before I tell the garage to drain my Bank Account.
 

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Discussion Starter #2
Mine has passed over, and the garage is quoting around £800. The part is £300, and incredibly labour intense. The prop shaft has to come out For a start. They tell me it takes 8 hours.
Any views appreciated before I tell the garage to drain my Bank Account.
This is a NRF EGR Valve failure.
 

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Cost of the EGR sounds about right and it's about 5 hours labour to change based on what others have reported.
 

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Unfortunately this is by no means an isolated case. A member of our family had the "fix" applied to her SEAT and the egr failed whilst she was in Wales. The fix lowers the burn temperature and causes more soot. She was advised by a garage to join the AA in case her car had to be transported back to her home in Cornwall, as Wales had "run out" of EGR's. The Yeti diesel engine needs long journeys and I see yours did only 55000 miles in ten years. Even if yours has not had the fix the mileage and vehicle age are not ideal. Replacing the EGR is a major operation with a huge amount of dismantling. The labour charge of £500 is not unrealistic.
 

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Yup. Everything The Hood said. :)

The EGR valve is down the back of the engine as you look at it. Buried way down below the turbo and manifolding. Recommended access route is from below. Which is not too bad for a 2WD Yeti. But a 4WD there is far more stuff that has to come off first. Prop shaft, exhaust, most of the power take off, bevel gear housing, etc. Bit of a ‘mare of a job. Hence the hours.

In theory it is possible to clean off all the encrusted soot and get the EGR working again. If you are paying someone else to do that though, then you would incur much the same as the £300 cost of a new valve unit anyway. You don’t want to have to do the whole dismantling thing again in six months time. So a new valve unit works out the best value in the end.

Personal experience says, if the EGR valve itself is clogged up, then both the Throttle Body on the front of the engine, and the EGR outlet nozzle into the inlet manifold, won’t be far behind. Might be worth getting them cleaned up too? Before they start to give faults. Plus my theory is that as those start to get clogged, that reduces the gas flow through the valve at the back, so that clogs faster. The throttle body and outlet nozzle are both much more easily accessed on the front of the engine. Removing and cleaning them is a perfectly feasible DIY job. And is the subject of a “How to” blow by blow description in this very forum....

After that, prevention is better than cure. It may be worth considering getting the VW NOx “fix” reversed by an ECU remap. If not already done? And / or using a fuel additive that helps to keep the exhaust system more clear. Using something such as one of the Archoil 6400 or 6900 Dmax additives. As described elsewhere in a number of threads.
 

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I've still got a nearly full bottle of Archoil on a shelf in the garage. Only took one treatment out of it.
 

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I've still got a nearly full bottle of Archoil on a shelf in the garage. Only took one treatment out of it.
AR6900 I presume? Dr Livingstone? How much would it take to arrange leverage off your shelf? (Packaging up to send in a leak free way, might cost more than it’s worth mind?) Pity I’m not travelling so regularly to Shrewsbury/Telford any more? Or we could have arranged a pick-up meet perhaps on one of your Good Samaritan trips over the border crossing? If we’re out of lock down by mid-April, I’m due one more trip some when around then. For my official “retirement dinner”.
 
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If you are able to do your own servicing, the throttle body mentioned above can be DIY cleaned without paying a garage to do it. If this were a Haynes manual cleaning the TB would be an "intermediate" skill level requirement as there is the potential to cause damage/problems if not done correctly.
There is a link below to a how to guide, and another to a PDF which means you can print a copy to have to hand if needed. If you don't feel up to doing it yourself you can read about what you are paying someone else to do.


 

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AR6900 I presume? Dr Livingstone? How much would it take to arrange leverage off your shelf? (Packaging up to send in a leak free way, might cost more than it’s worth mind?) Pity I’m not travelling so regularly to Shrewsbury/Telford any more? Or we could have arranged a pick-up meet perhaps on one of your Good Samaritan trips over the border crossing? If we’re out of lock down by mid-April, I’m due one more trip some when around then. For my official “retirement dinner”.
Henry
£10 and perhaps a little more to post it?
I can certainly pack it up securely, but whichever is easier for you. Don't very often go to Telford Hospital, it is more often to Shrewsbury when doing "local" runs.
PM me your address.
 

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Discussion Starter #10
Yup. Everything The Hood said. :)

The EGR valve is down the back of the engine as you look at it. Buried way down below the turbo and manifolding. Recommended access route is from below. Which is not too bad for a 2WD Yeti. But a 4WD there is far more stuff that has to come off first. Prop shaft, exhaust, most of the power take off, bevel gear housing, etc. Bit of a ‘mare of a job. Hence the hours.

In theory it is possible to clean off all the encrusted soot and get the EGR working again. If you are paying someone else to do that though, then you would incur much the same as the £300 cost of a new valve unit anyway. You don’t want to have to do the whole dismantling thing again in six months time. So a new valve unit works out the best value in the end.

Personal experience says, if the EGR valve itself is clogged up, then both the Throttle Body on the front of the engine, and the EGR outlet nozzle into the inlet manifold, won’t be far behind. Might be worth getting them cleaned up too? Before they start to give faults. Plus my theory is that as those start to get clogged, that reduces the gas flow through the valve at the back, so that clogs faster. The throttle body and outlet nozzle are both much more easily accessed on the front of the engine. Removing and cleaning them is a perfectly feasible DIY job. And is the subject of a “How to” blow by blow description in this very forum....

After that, prevention is better than cure. It may be worth considering getting the VW NOx “fix” reversed by an ECU remap. If not already done? And / or using a fuel additive that helps to keep the exhaust system more clear. Using something such as one of the Archoil 6400 or 6900 Dmax additives. As described elsewhere in a number of threads.
Thank you very much for that explanation. As I understand it the principle of EGR is to control a proportion of the exhaust gas and send it back into into the engine. It recirculates the gas, cools the combustion somehow, which reduces NO2.
Does driving style affect this? The particulation filter can be blown out with a hard drive for example. My wife drives short journeys every day, and I try to blast it once a month.
Do the fuel additives you mention work well?
The cost of this part, plus a 60,000 mile service came to £980. Gulp, and the garage told me the springs in the rear shock adsorber had failed, but safe to drive. This repair, inclusive is costed at £260. Comments appreciated.
What a great Club this is !!
 

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To the first part: yes. Exhaust Gas Recirculation was first introduced on petrol engined cars in California during the early 1980s. Bringing around a proportion of the exhaust gases and feeding those back into the inlet side, denies the combustion process of some of the oxygen it needs for a maximum burn. This in turn reduces the maximum combustion temperature and thus reduces NOx creation. Also robs the engine of some of its performance, but in modern engines that is compensated for by the electronic mapping of fuel injection.

Recirculation is not needed all the time. Only at times when cylinder temperatures would be highest - during periods of higher loading or maximum power and acceleration. Climbing hills, towing, etc. In conditions of light load, such as constant medium throttle position such as cruising at a steady speed, when cylinder temperatures are naturally lower anyway. Then EGR is not needed. Better efficiency without it. Hence there needs to be valve under control of the ECU, to shut off the EGR flow at those times when not needed.

On Diesel engines that’s where the problem comes. Because those tend to produce more soot in the exhaust gas anyway, the valve can get clogged with soot, and then cease to function correctly. Because the butterfly flap can’t achieve the full range of its travel.

Yes, using a car for short trips only will definitely clog up the valve MUCH faster, compared to car that spends its entire day blasting up and down motorways at full operational temperature. That’s because all the time the engine is running cold, or or only partially warmed up, it is burning more fuel to maintain performance. Consequently producing more soot.

Regular “blasts” to use the car properly, should in theory help keep the EGR system slightly more clear. By encouraging more hot gas flow through the recirculation system. But they do need to be regular. Not just occasional. And only partially effective, as once the soot has accumulated and hardened on the valve's internal surfaces, it is very hard to shift. Think of it perhaps like a 1950's petrol engine? Where an under-used car needed a "de-coke" of its cylinder head every 30,000 miles or so.

Similar principle applies to keeping a DPF clear, giving it chance to regenerate regularly. Although active regeneration also involves injecting more fuel during the exhaust stroke, to raise exiting exhaust gas temperatures into the 5-600 degrees range (or higher), double the normal gas temperature. (All details revealed using the VAG DPF smartphone app.)

Prevention is better than cure. Which is where the additives come in. Some of those claim to “cure” a blocked EGR valve? I’m not so sure about those? Maybe they do? Maybe they don’t? One for regular (every tankful) use that has some proper science behind it, and some anecdotal backup of effectiveness from members in this forum, is Archoil AR6900 D-Max. I started using it regularly around 3 years ago, after listening to some other members. So far so good. Last time my Yeti needed its EGR valve replaced was at around 125,000 miles. At 5.5 years old. Now it’s nearly 11 years and near 232,000 miles. Still with that same EGR valve. Mmmm....

I also clean out the Throttle Body (much easier to reach on the front of the engine). Along with the nozzle where the exhaust gas exits into the inlet manifold. A manual process every 12-months to 2 years or so. On the theory that free flow of the exhaust gas at that end of the system helps keep the harder to reach valve at the back clearer too?

Last: The “assister springs” or hard foam “bump stops” - the orange coloured things that sit on top of the rear dampers - are quite easy to change for a competent DIYer with normal tools and jacks, etc. Cost about £25/pair new, genuine OEM. IF that's what your garage were referring to? One of these lockdown days, but not today, I’ll get around to completing the “how to” write up from when I did those on our Yeti.
 
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One thing to add to the above post, is that any additive in the fuel is burnt before it reaches the EGR.
But it probably leads to less soot reaching it because of a cleaner burn.
 

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One thing to add to the above post, is that any additive in the fuel is burnt before it reaches the EGR.
Then why put the above without a few more words?
 

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Excellent article either way. Which emphasises that AR6900 especially, contains combustion catalysts and additives that help maintain clean, lower soot combustion, that in turn help even downstream of the cylinders.

Also re-reading that reminds me to add that during short trip runs, while the engine and particularly its oil are not fully up to temperature, more oil is getting past rings and valve guides, or crankcase gas being recirculated back to the engine inlet. So adding to the effect of oil polymers mingling with the soot in the exhaust gas, and further contributing to the whole EGR soot build cycle. Till the engine is fully running at optimum temperature. While the oil itself normally takes a little longer to reach optimum temp. (Less time in the VW EA189 engine family because they incorporate an oil/coolant water heat exchanger. That works both ways to cool the oil at high temperatures, but also heat it from the engine coolant during initial warm up phase). Creating even more soot deposits during engine warm up, over and above the extra fuelling I mentioned earlier.
 

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Discussion Starter #17
T
To the first part: yes. Exhaust Gas Recirculation was first introduced on petrol engined cars in California during the early 1980s. Bringing around a proportion of the exhaust gases and feeding those back into the inlet side, denies the combustion process of some of the oxygen it needs for a maximum burn. This in turn reduces the maximum combustion temperature and thus reduces NOx creation. Also robs the engine of some of its performance, but in modern engines that is compensated for by the electronic mapping of fuel injection.

Recirculation is not needed all the time. Only at times when cylinder temperatures would be highest - during periods of higher loading or maximum power and acceleration. Climbing hills, towing, etc. In conditions of light load, such as constant medium throttle position such as cruising at a steady speed, when cylinder temperatures are naturally lower anyway. Then EGR is not needed. Better efficiency without it. Hence there needs to be valve under control of the ECU, to shut off the EGR flow at those times when not needed.

On Diesel engines that’s where the problem comes. Because those tend to produce more soot in the exhaust gas anyway, the valve can get clogged with soot, and then cease to function correctly. Because the butterfly flap can’t achieve the full range of its travel.

Yes, using a car for short trips only will definitely clog up the valve MUCH faster, compared to car that spends its entire day blasting up and down motorways at full operational temperature. That’s because all the time the engine is running cold, or or only partially warmed up, it is burning more fuel to maintain performance. Consequently producing more soot.

Regular “blasts” to use the car properly, should in theory help keep the EGR system slightly more clear. By encouraging more hot gas flow through the recirculation system. But they do need to be regular. Not just occasional. And only partially effective, as once the soot has accumulated and hardened on the valve's internal surfaces, it is very hard to shift. Think of it perhaps like a 1950's petrol engine? Where an under-used car needed a "de-coke" of its cylinder head every 30,000 miles or so.

Similar principle applies to keeping a DPF clear, giving it chance to regenerate regularly. Although active regeneration also involves injecting more fuel during the exhaust stroke, to raise exiting exhaust gas temperatures into the 5-600 degrees range (or higher), double the normal gas temperature. (All details revealed using the VAG DPF smartphone app.)

Prevention is better than cure. Which is where the additives come in. Some of those claim to “cure” a blocked EGR valve? I’m not so sure about those? Maybe they do? Maybe they don’t? One for regular (every tankful) use that has some proper science behind it, and some anecdotal backup of effectiveness from members in this forum, is Archoil AR6900 D-Max. I started using it regularly around 3 years ago, after listening to some other members. So far so good. Last time my Yeti needed its EGR valve replaced was at around 125,000 miles. At 5.5 years old. Now it’s nearly 11 years and near 232,000 miles. Still with that same EGR valve. Mmmm....

I also clean out the Throttle Body (much easier to reach on the front of the engine). Along with the nozzle where the exhaust gas exits into the inlet manifold. A manual process every 12-months to 2 years or so. On the theory that free flow of the exhaust gas at that end of the system helps keep the harder to reach valve at the back clearer too?

Last: The “assister springs” or hard foam “bump stops” - the orange coloured things that sit on top of the rear dampers - are quite easy to change for a competent DIYer with normal tools and jacks, etc. Cost about £25/pair new, genuine OEM. IF that's what your garage were referring to? One of these lockdown days, but not today, I’ll get around to completing the “how to” write up from when I did those on our Yeti.
Thank you.
A quite remarkable post, and beautifully written.
I will invest in the product you describe, because my Wife is always going to drive short journeys.
My 20 year old Golf Gti has not such problems, and I love it to bits.
it just works.
 

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My 20 year old Golf Gti has not such problems, and I love it to bits. it just works.
That's because it is twenty years old and not hampered with all the "improvements" and filters, keep it as long as you can.
 
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