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Unread 02-11-2005, 03:45 AM   #1
soldierguy
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CRD...will it clog intakes like the VW TDI?

Ok...I know the CRD has just hit the streets so there aren't many of them around and probably none that have a fair number of miles on them (20K+) but something is on my mind.

Anyone wonder if the Liberty CRD intake will be likely to clog with sludge like the VW TDI?

I'm asking because it's a well documented issue over at http://www.tdiclub.com and by VW...do a search on the tdiclub site for CCV or intake clogging and you'll see what I'm talking about. I’m no vehicle guru or engineer, but from everything that I’ve read it's caused by the combination of an EGR valve (which the Liberty CRD and the VW TDI have) and a PCV valve (or CCV, Crank Case Ventilation valve). As I understand it, it goes something like this: PCV valve vents air into the intake stream (after the air filter and before the turbo) that has a bit of oil & crankcase gasses in it. EGR directs exhaust gasses (containing some soot because it hasn’t hit the catalytic converter yet) back into the intake stream whenever lean conditions occur...it does this because lean conditions create NOX (don’t ask me why but I think it has something to do with the high cylinder temps caused by lean conditions), the catalytic converter can't burn off the NOX because US diesel fuel contains too much sulfur, and the sulfur would destroy a gas-engine style 3-way cat (using a 2-way cat that isn't designed to burn off NOX is my understanding of what’s used in US diesels). Apparently EGR helps cool the cylinders enough to help prevent excess NOX from being formed, so that's why the EGR valve is there...to help reduce NOX so the vehicle can meet emissions requirements. Anyway, apparently the combination of the soot from EGR and the oil from the PCV mix and form a sludge that sticks to the intake manifold walls and intercoolers on the VW TDI. This stuff builds up over time and has to be cleaned out to restore power & efficiency. VW TDI owners are intimately familiar with this...some have to clean their intake manifolds & intercoolers every 20K-50K miles, others have never had an issue with it.

The thinking seems to be that if you eliminate or greatly reduce either the soot from EGR or the oil from PCV that the clogging problem is greatly reduced. Limiting EGR activity is not easy...some VW TDI owners simply disable the EGR valve and live with the check engine light, while others use software to limit EGR activity. And many VW TDI owners use a more robust filtering system between the PCV valve and the air intake like the one at http://www.reliableindustries.com/ca...NH/provent.php to remove most of the oil from the equation.

It seems to me that the ingredients that create the clogging in the VW TDI are also present in the CRD. Low sulfur fuel seems to be the answer...low sulfur fuel (less than 15 ppm) would enable the use of a 3-way cat to kill the NOX and would likely eliminate the need for EGR or at least reduce EGR operation to a point where it wouldn't be an issue. It’s not really an issue on gas engines that use EGR…there’s far fewer particulates of soot in the exhaust of a gas engine, so by default one of the two ingredients to the sludge is mostly absent.

It's not a deal-breaking issue for me...even if I have to clean the manifolds now and then I still want a CRD. And who knows...maybe this won't be an issue for the Liberty CRD at all. After all, the injection system is different (injector pumps for the TDI and common rail for the CRD); the TDI is absolutely tuned for economy (lean mixtures requiring aggressive EGR activity), and the CRD doesn’t seem to be tuned for economy…VW TDI mileage is about 50% better than the gas 2.0, where CRD economy is only about 25% better than the gas 3.7, telling me that the CRD might run a little more rich than the TDI and it depends on the cat to clean up the exhaust more than the TDI…if it does, then EGR operation would be less than in the TDI due to reduced cylinder temps caused by more fuel being injected (if I assume that fuel acts as a coolant before it explodes). And the intercooler on the VW TDI may have something to do with it as well…cooling the mix of air, soot, and oil to a point where it can condense and stick to the walls of the intercooler and intake manifold…I’m not even sure if the CRD is intercooled or not (shows you my level of knowledge…LOL).

Thoughts? Please feel free to point out errors in my information, thinking, assumptions, etc…I’m here to learn just like everyone else.

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Unread 02-11-2005, 06:24 AM   #2
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I thought the newer Cummins also now have an EGR, it is an issue, I do have a cel light with my TDI now, and about every 100,000 miles (highway) you need to clean the TDI intake, will just have to see. With modifications you can eliminate this issue, but it sure would be nice if the low sulfur helps. I don't clean mine at all now with 235,000 and going strong. I would still buy one and see what it does, they can always be cleaned.
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Unread 02-11-2005, 08:47 AM   #3
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ULSD will be law on June 1st, 2006 (474 days from now). I'd say it'd be close to impossible that any of the CRD's will be used enough to get clogged up by the time ULSD is mandated. As we get closer to 6/1/06, more and gas stations will have ULSD. Once you find a station that sells it, keep filling up there till all the other stations switch over 6/1/06. I've been driving my VW Golf TDI since 8/2002 and I have 41,000 miles on it. No problems at all. My buddy has one too, 90,000 miles on his. I talked to a pizza delivery guy that has a 2002 VW TDI, he's got 200,000 miles on his with no problems. I couldn't believe he has that many miles on it till I looked at the odometer myself.
The full size trucks have EGR's on them. The Duramax has always had it. The Ford with the 6.0 has it. These guys pack on the miles too. I seached the Ford forum and couldn't find anyone with a clogged intake.
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Unread 02-11-2005, 01:51 PM   #4
soldierguy
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I'm not too worried about it...if I have to clean the intake manifold now and then it's no big deal. And I'm glad to hear that your TDI is going strong. It's just curious to me that some TDIs have the issue and some don't. And if it doesn't seem to happen on the diesel full-size trucks at all, then that leads me to believe that it's a tuning issue for meeting the emissions regs...the full-size trucks have different emissions standards than a light-duty diesel like the TDI and CRD.

And yeah running ULSD will be a good thing to do for the environment, but I'm not sure it'll do anything in terms of EGR operation (one part of the sludge equation on the VW TDIs). Assuming that my info and understanding is correct (a BIG assumption!), EGR operation is a result of an oxygn sensor in the exhaust stream detecting too much NOX, which is in turn a result of lean conditions and the resulting high cylinder temps. Running ULSD won't change the fact that there's a 2-way cat in the exhaust pipe that's not able to deal with excess NOX.

It'd be interesting to see a comparison of emissions tests for all the components of diesel exhaust for the VW TDI, the CRD, and a full-size truck like the Dodge Cummins or a Powerstroke. Ok, maybe it'd just be interesting to me...I'm always curious about why & how things work & happen. But it might illustrate how the different engines are tuned...back to one of my thoughts, I'm curious if the VW TDI is tuned to run really lean and the others are tuned to run more rich...that would have a direct impact on NOX production and EGR operation.
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Unread 02-11-2005, 03:14 PM   #5
ukliberty
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Well the CRD has been kicking around in Europe for a while now and I have not heard of any issues.
Dealers recommend that you put a fuel treatment additive in at the service - but I think that is more so they can charge you $18 for a $2 squirt of liquid.

I have only 25,000 on mine so cant say I have had any problems but there are quite a few out there with much more on them.

One thing the CRD does not like is slow city driving - you have to make the engine work every now and then otherwise it seems to get a bit lazy.
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Unread 02-15-2005, 06:56 AM   #6
aburchell44
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This is also very true for all diesels, especially VWs. I cannot believe how many VW owners oare on here. I am looking into getting a Diesel jeep in the next year. Maybe a used demo or something... Are they going to be avaliable in CANADA????
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Unread 02-15-2005, 09:12 AM   #7
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Hi
We have low sulphur diesel in UK and I haven't heard of VWTDI or Jeeps getting this problem over here. I know what you mean about the lazyness UKLibby so I gun mine plenty
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Unread 02-15-2005, 12:48 PM   #8
blitzkreig
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Quote:
Originally Posted by aburchell44
Are they going to be avaliable in CANADA????
Sooner or later they will be. The ditsy dealers know nothing about their pending arrival but that doesn't indicate anything.
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Unread 02-15-2005, 02:21 PM   #9
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Quote:
Originally Posted by blitzkreig
Sooner or later they will be. The ditsy dealers know nothing about their pending arrival but that doesn't indicate anything.
www.jeep.ca finally has some spec info on the CRD for Canada with late availability noted. You still can't build and price one online but you can place orders at dealers. Considering the new models hit in August/Sept I'm guessing June/July time for availability.
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Unread 02-22-2005, 07:40 AM   #10
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Talk about a piss poor marketing/Sales product launch... Ill stick to the VWs...

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Unread 03-03-2005, 11:22 AM   #11
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