It would be interesting to queue the owners of failed EGR's to see if they allow at least 1 minute of idle time before shut-down.

I just note the time when I arrive home, remove computer case, cellphone, briefcase from the CRD, transfer them to my home office and then return to shut down - an easy 3 minutes.

That's too funny, I do the same when I get home to get all my stuff out of the KJ, just leave it idle while I get everything in the house.

DZL_Lou if we are to get a block plate fashioned for later use with any type of workaround, we will
need an exact trace of the outline of the egr and inside mount area with holes. Do you have this
EGR in your possession to get the trace done? Better yet if you have it and we get it somewhere
that will machine the block plates. Let me know.

Sorry I haven't responded sooner...just got back from vacation in Florida and I have two 2.5L VM's on engine stands in my garage that I brought home from school that are getting rebuilds. I'll post up some pics.

I know that in the early stages of EGR failure it was due to oil in the pipe. What would happen is that the oily residue would build up around the shaft of the EGR valve and then when shut off hot or after cooling for a while, the coked oil would build up on the shaft and prevent full movement, eventually not moving all together. The problem is that the EGR valve is before the EGR cooler and not after it, so it's always subjected to the hot exhaust flow (bad design). Sometime in the 05MY run there was a TSB update to the software for a cleaning routing that would help prolong the situation, but it's still far from perfect. A better solution would be to mount the EGR valve inbetwen the EGR cooler and the FCV where the exhaust gas is considerable cooler. On the 2.5L engines that we have, this is how it is configured, and after hundreds of hours of use (i.e. beating them unmercilessly on the dyno) the EGR still functions with no problem.

As far as blocking off the EGR flow, it'll most certainly disrupt engine operation. If you block it off but don't unplug the FCV and EGR valves, it'll chug itself to death and not run at all. If you unplug the two, you'll get the same codes as mentioned earlier in the thread - limp home shouldn't occur, those two components will just not work. Emissions will also never pass if you're required to run smog, and it might smoke some more for obvious reasons. The intake tract, however, will be much cleaner - if you were to look inside the intake ports of the head, they'd be literally gunked up with oil from the stupid design...

A better solution would be to mount the EGR valve inbetwen the EGR cooler and the FCV where the exhaust gas is considerable cooler

I used to think blow-by oil was the primary cause of egr failure also - that's why I installed a Provent on my CRD in April 2005. However, 2 replacement egr's later, I'm convinced that in spite of running a lot of B20 and PS in every tankful, the sooty exhaust being recirculated back into the intake system is definitely the major contributor to the problem. The CAC oil will accelerate this issue, but from my experience, when removed, does not eliminate it. A study consiting of a single sample

My first egr failed due to carbon buildup according to the tech who removed it, at 8K miles and the provent had been on for 5.5K miles, with only 2500 miles without it. The carbon was much harder looking than the buildup on the valve in your pictures. It may be that in the hot summer weather in the southeast, the soot carbonizes on the egr valve areas faster than it would otherwise - similar to a cake slowly burning in the oven when left in too long at too high a temperature. The extra heat load on the cooling system from egr is estimated to be as much as 40% according to some estimates I've seen - this will result in more heat load for longer periods of time, exacerbating the heat buildup in exhaust temperatures, further causing carbonizing of the soot in the egr chamber.

I would be interested in seeing how many "long life" egr valves, those with 25Kmiles or more without failure, run in colder or moderate climates in the northeast or western northern states. This is inspired by a long study published on tdiclub, where certain tdi owners worked in companies with access to scientific equipment capable of anaylsis for early failure of MAF sensors. His final analysis, was that defective solid state design of the heater element on the MAF, exacerbated by cold temperatures of northeastern states, Mass, Conn, N.H. etc, caused the heater to run longer duty cycles and expose the weakness of the design. His findings were based on TDI owners sending in their failed MAF sensors to him from all over the US and he noted that the repeated MAF sensor failures were from owners in northeastern states. That's why I'm wondering if CRD owners with multiple egr failure have something in common, i.e. long idle times, hot climate, predominately highway miles driven, long traffic light times or any condition which would cause the egr to cycle on longer, heat the soot in the valve chamber for longer than average.

On my CRD, the 2nd egr failed at 12K, full provent protected miles later(20K odometer miles). Again, according to the tech, it wasn't electrical failure, but carbon buildup on the valve that caused it to go bad. For all I know, the egr valve might be sold separately from the solenoid - it's possible that I'm still running the orignal solenoid. So while the provent has been a tremendously worthwhile investment to keep blowby oil, which we know to be somewhat excessive, out of the egr and intake system, it alone cannot prevent failure of what I believe to be a inadequate lifecycle egr design.

After seeing your pictures, I'm now even more convinced that the egr valving size, in comparison to the TDI closeup pictures I've seen, is insufficient to handle the amount of soot buildup and eventual carbonizing that occurs. It could also be inadequate design of the shaft that this valve seat runs on causing sticking. The carbonizing I'm referring to is a result of the agressive cycling that prev 07 EPA emissions required of this system. You can infer that current egr technology was at it limits of effectiveness by the fact that it couldn't meet the even more stringent 07 and 09 EPA diesel emissions requirements - hence the SCR and plasma systems being designed for newer diesel engines. Being at its limits can also infer that our egr designs are cycling the maximum egr gas into the engine that it can handle and still run - further supporting the idea that excessive carbon buildup is repsonsible for failure of these systems.

If solenoid failure were the cause, I don't believe the TSB would list the actual valve itself on the replacement parts list. Also, on my first egr replacement, the tech told me that Star required a battery of photographs of the carbon buildup within the valve to be sent to them before they would release the replacement part. This speaks to unexpected failure modes, probably due to direct lack of experience of repair on such a high duty cycle of egr gas and soot traversing the valve system. Industry research with paying owners contributing down time under warranty to the knowledge base.

While the EPA emissions doesn't require a certain amount of oxygen deprived exhaust gas to be injected into the intake of the engine, their absurd NOX reduction requires lowering of the burn temperature from optimum for any diesel engine to lower NOx output. This is where the performance loss that Pablo speaks of is coming from. For longer term results, we have not even begun to experience the results of the grit from egr being reintroduced into the cylinders over hundreds of thousands of miles yet. Most original owners will not have the vehicle when this effect shows up.

The cooler you speak of is quite large in comparison the egr valve itself - I'm now wondering if it isn't slowly clogging up due to the small passage sizes the soot must flow through before exiting into the intake system on the engine.

To put a common sense big picture perspective on all of the grief this system is causing owners everwhere - the egr is there primarily to reduce NOx emissions by a miniscule amount (not precentage but actual grams) from 04 standards - for a theory that the EPA cannot conclusively prove to the satisfaction of scientists that NOx is the major reason for smog creation - with real world evidence every weekend in California refuting the EPA position on NOx to smog creation. An abuse of regulatory authority that is costing citizens paying the salaries of these EPA faschists hundreds of millions of dollars annually due to restriction of diesel powered fuel effecient vehcile availability in the marketplace.

Further, it is now believed by some scientists that smog is actually going to increase as a result of NOx reduction - if that turns out to be the case, the entire EPA leadership should be terminated, with pressure on our legislatures to replace them with objective EPA leadership who can use their authority for solving problems instead of pursing personal agendas.

Again, thanks for the pictures. I see its a Pierberg unit rather than a Bosch.

Ok,


In seven pages of some ranting and some info... has anyone come up with a way to disable the egr w/o throwing a cel??
Dad

So I just did the service at 20K still need to clean the MAF sensor.

You don't clean the MAF sensor. (MAF = Mass Air Flow) If you do you will most likely destroy the sensor.

-nix