EGR Valve revisited

whitedog

New member
OK, so the EGR valve in our 2005 took a dump last week. It would occasionally had a constant high pitched squeal and the EGR code. (P0401, I think) Replaced the valve then like a real man, I took that sucker apart. The security Torx split the motor half from the valve half and in between is an hour glass shaped drive mechanism with a plastic coupler in between the two halfs. That coupler had fallen apart so it wouldn't open the valve all the way resulting in a low EGR flow code.

It makes me wonder how many EGR valves have failed due to this coupler failing.

There is a gasket in there but it's just protecting the drive parts from the elements and putting a bit of ultra black on the gasket would seal things up just fine.

But sourcing the drive coupler could be a bit problematic. My thought would be to have one printed on a 3D printer, but I don't know if those things can make a reliable part for this situation.

I will look into this further.

BTW, I did a bit of searching and found a PDF of some collected EGR discussions and I skimmed through that and the only thing I found was not to take it apart.
 

jmoller99

Own a DAD ODB2 Unit.
You are probably right about this single part killing a lot of EGRs. I am scared to do more than clean them (because they are very expensive).
 

whitedog

New member
I was wrong about one thing. The gasket seals coolant inside and from getting to the rotating part in the middle. But again, a thin film of ultra black will seal it well.

I know that the metal parts of the coupler are marked with KTR and KTR is a German company that makes couplers but I couldn't find the right coupler. Is there anyone here in Germany?
 
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seans

Member
I need one of these plastic parts, and spent hours looking online. I believe that our EGR contains a "jaw coupling" and that this plastic piece is called a "spider". I found a price of 1.75 Euros (about $2.50) on KTR's site (thanks for the tip, Whitedog) for a non-matching spider that is about the same size. So IF they were available, they might be dirt cheap! :cry:

A search of the KTR site found no similar spider so I wonder if Wahler contracted KTR to make a custom version for them. I could not find a similar spider anywhere else.

As for 3D printing, these need to withstand PWM vibration and high temperatures so fabricating one may need special materials consideration. :frown: KTR color-codes their spiders for hardness and material type. Green ones are made of Hytrel with 64 Sh hardness and can withstand a temperature range of -50 to +120 C (and higher temperatures intermittently). Light green ones made of polyurethane with the same hardness but a lower temperature range. The picture below looks like light green, but the part is actually darker than it looks in the image, and without a reference I cannot tell which type it is. Additionally, Wahler/KTR may have specified a different kind of material back in 2003/2004.

A comparison of data sheets for Hytrel 6356 and Hytrel HTR8163HVBK against those provided by 3D printing shop shapeways.com for the materials it has available for printing suggests that shapeways' materials might be too hard, too brittle, and/or too low temperature for this application.

I am not a mechanical engineer, so none of the information I'm providing should be relied upon.

Unfortunately this still leaves us in the position of having to go to Wahler for the spider. Perhaps one of our vendors can reach out to Wahler. It is also possible to get the inventors' names from patent filings.

Our best bet may be to see if there are EGRs from different vehicles that also contain this coupling. The NCV3 EGR valve body is not compatible but maybe it uses the same coupling. It would at least give more options when searching for junkyard EGRs to be potential spider donors at a lower cost.

As for why mine failed at 108,000 miles, it was probably damaged when an emergency repair led to a kink in a hose that restricted coolant flow to the EGR. :bash:The damage suggests that the side of the coupling connected to the the rotary valve and exposed to exhaust got too hot, and melted the spider. You can see in the photo how portions of the spider are melted and show charring while other portions do not. (Can someone post a photo of an undamaged spider?)

So it's a one-off failure, but it does suggest that there is a failure mode related to over-temperature conditions.

jaw-coupler-spider.png

jaw-coupling-hubs.png
 

whitedog

New member
seans, that is great information. The coupler that I have is in pieces, but they are not melted like yours is. This suggests to me that the Hytrel would be the better way to go. If it were my personal van, I would pull it apart and get good measurements and a picture but it's not mine to play with.

It would be nice to be able to drop in a little part and fix it instead of sending the big money on an entire valve.
 

seans

Member
It would be nice to be able to drop in a little part and fix it instead of sending the big money on an entire valve.
A rebuild kit would contain this spider and a gasket. It kills me that we are throwing away perfectly good EGRs for this. What's the best way of escalating this so that MB or Wahler can provide these parts separately?
 

surlyoldbill

New member
I think Dr A looked at making a rebuild kit, and discovered that the manufacturing process and design made that option too costly or difficult.
 

skydiver007

DRB III Owner If You Need
The squealing sound you heard is probably the self cleaning cycle the egr goes through when the key is turned off and the squeal is perfectly normal. The normal failure is a buildup of gunk and carbon and can normally be cleaned up. Once you take the egr apart, good luck getting it back together properly. They hardly never work again once you take the coupling part apart.
 

Aqua Puttana

Poly - Thread Finder
...They hardly never work again once you take the coupling part apart.
That is true from all the posts here. Nobody has yet to indicate that they didn't need to replace the EGR after opening that section of the unit.

Do NOT remove the security screws unless you plan to replace the EGR unit anyway.

I suspect that when the two parts are separated the parts move out of original position without even being noticed. When the valve is reassembled the indexing is lost and the improper EGR operation is noticed by the ECM (aka ECU).

I have a perfectly good used spare EGR because I replaced it during the Delphi O2 sensor partial failure, LHM air mass code debacle. I'm not going to take it apart to explore because it works just fine now. Good luck. vic
(Click on the blue arrow in the quote box to go to the thread.)

Doktor A explored a rebuild kit for the OM612 style valve and determined that it was not worth pursuing. I don't recall any comments as to the OM647 style EGR valve.

IF it can be properly re-assembled, I have been successful making one off custom parts similar to the EGR plastic coupler. It takes time, but if you are determined it is surprising what can done with some handsaws, grinding wheels, and files.

I'll repeat my request. If anyone figures how to properly index and re-assemble the OM647 EGR valve please post a Write-up. vic
 

seans

Member
I could be wrong, but I don't think that realignment during reassembly requires precision - just don't break the plastic piece. I tore one apart and there seems to be a magnetic position sensor but it looks like it can work with the actuator rotated 0 or 180 degrees. I put it back together with a substitute for the plastic spacer and was able to operate it for an hour without throwing a code.

I think in the cases of a failed reassembly, the problem is that either the circuitry in the EGR was at fauit, or the spacer wasn't replaced, or the spacer broke during reassembly because it was deformed and made brittle from heat.

As for a kit, the idea would be to get the parts from Wahler or KTR. Injection molding the plastic piece would cost less than $1 for each part except the first which would cost $5K-$10K for the mold and setup.

With some cleverness, craftsmanship, and different material, one can be hand fabricated. The problem, though, is not knowing why the original material was chosen, and what failure modes its choice prevents. :frown:


magnetic-position-sensor.jpg
Above: the inside of the top of the EGR. When assembled, a round magnet on the top of the actuator shaft protrudes into the center part. Note the broken tabs - don't try this at home.


possibly-a-cpu.jpg
Above: the printed circuit board under the cover. To save space, integrated circuits aren't even packaged; their dies are bonded to the board. The board is potted in a transparent, sticky gel. The EGR was destroyed to give you these photos.
 

EZoilburner

03 2500 158wb HR
It is such a shame they can't be rebuilt, on mine, the arm moves with ease and yet the egr does no work. When I was looking at it I thought the controls for the egr should be on the top to avoid so much oil soaking on it.
 

Aqua Puttana

Poly - Thread Finder
My opinions.
I could be wrong, but I don't think that realignment during reassembly requires precision - just don't break the plastic piece. ... I think in the cases of a failed reassembly, the problem is that either the circuitry in the EGR was at fauit, or the spacer wasn't replaced, or the spacer broke during reassembly because it was deformed and made brittle from heat.
Maybe. But many have tried and I would assume that not all were heavy handed. :idunno:

... With some cleverness, craftsmanship, and different material, one can be hand fabricated. The problem, though, is not knowing why the original material was chosen, and what failure modes its choice prevents. ...
My guess is that plastic is the material of choice because it is cheaper. When in doubt, follow the money. For custom DIY handmade duplication I see no reason that aluminum could be a poor choice other than workability.

:2cents: vic
 

seans

Member
My guess is that plastic is the material of choice because it is cheaper.
To test your theory I placed a piece of the material next to a couple of cable ties and heated them with a heat gun in a very unscientific manner (photos below). If the spider was made of a higher temperature material it should take longer to melt. In fact, it melted more readily.

before-after-melt.jpg

approx-temp.jpg
Temperature is VERY approximate (+/- 50 F)
 

seans

Member
It is such a shame they can't be rebuilt, on mine, the arm moves with ease and yet the egr does no work. When I was looking at it I thought the controls for the egr should be on the top to avoid so much oil soaking on it.
Did you disassemble it, and if so, is the plastic piece intact or in pieces?
 

seans

Member
I believe that's the part.

A Sprinter owner near me has chosen to buy a new EGR valve rather than attempt to fix his. Given how Sprinter systems seem to be interdependent, and that operation of the EGR valve can affect engine temperature and turbo boost, I can see the wisdom in purchasing new - and avoiding downstream issues with these components - rather than attempting a repair.

Also, this part is not the only cause of EGR valve failure. Of the three EGR valves I've looked at, two had failed plastic parts, but one had the plastic part intact. In this EGR valve, the sleeve that holds the coupling shaft had worn unevenly such that the shaft no longer was seated properly and the internals rubbed against the case, causing the valve to stick open. This problem is not repairable. Replacing the plastic part on an EGR valve with this type of failure won't fix the problem. There is also the possibility of an EGR valve having an electrical failure.

One question raised is why some of these plastic pieces are cracking. Mine melted because a botched roadside repair left a kink in the heater core hose that also cools the EGR valve. But it makes me wonder if excessive heat is causing some of these to get brittle and eventually crack. We all know about the circulation pump failure in the heater system and some of us might let it slide if the temperatures are warm enough. But does a failed circulation pump restrict the flow of coolant to the EGR valve? Who knows?
 

whitedog

New member
That is it. At $23.00 I'm sure it's a profitable part. I would use this part knowing that it's "stable at temperatures up to 160 degrees". I also noted this part of the description:

Manufactured from a material having a low coefficient of friction and low temperature on the friction surfaces. The coefficient of friction when working on steel without lubrication or with insufficient lubrication is 0.17-0.20, with oil-lubricated - 0,014-0,020, with water as a lubricant - 0.02-0.05. A good anti-friction properties can be used in friction pairs without lubrication or with insufficient lubrication. The best lubricants are mineral oils, emulsions and water. Stable at temperatures up to 160 °. It is insoluble in most organic solvents, is not affected mild acids, alkalis and salt water.
It looks like they found the properties of the material in some database and added it in there to look good. It talks about friction for a part where friction is not really a factor. Strength is the main factor with heat resistance a close second. I would buy it expecting it to be a biannual replacement item, but i would rather do that than spend all of the money on a new EGR valve.
 

vertigo

2007 NCV3 3500 3.0l
Re: EGR Valve revisited (Successful Reassembly!)

That is true from all the posts here. Nobody has yet to indicate that they didn't need to replace the EGR after opening that section of the unit.

Do NOT remove the security screws unless you plan to replace the EGR unit anyway.


(Click on the blue arrow in the quote box to go to the thread.)

Doktor A explored a rebuild kit for the OM612 style valve and determined that it was not worth pursuing. I don't recall any comments as to the OM647 style EGR valve.

IF it can be properly re-assembled, I have been successful making one off custom parts similar to the EGR plastic coupler. It takes time, but if you are determined it is surprising what can done with some handsaws, grinding wheels, and files.

I'll repeat my request. If anyone figures how to properly index and re-assemble the OM647 EGR valve please post a Write-up. vic
I can confirm that it is indeed possible, and simple to reassemble the EGR after having removed the upper servo motor section of the EGR from the lower valve & body section, at least on my 2007 OM642 engine.

I initially made the same mistake as many others before me, removing the security screws and separating the servo motor when I was actually planning to remove the entire EGR assembly. Upon reinstallation, I immediately found my turbo boost and RPM limited (to about 2800rpm), and the ScangaugeII showed me a new P0404 TDC which would not clear.

To solve the problem, I disconnected the EGR wiring harness connection, again removed the 2 security screws on the EGR assembly, lifted off the EGR servo motor, rotated the motor shaft approximately 180 degrees, carefully verified that the plastic spider coupler was properly seated in the valve assembly, carefully reseated the servo motor into the spider coupler which required a slight rotation of the servo motor to align it for reinstallation of the security screws, reinstalled the security screws (including the metal bonding bar which seats under the right-side security screw and hooks under the metal housing of the top of the servo motor assembly), and reconnected the wiring harness.

Problem solved! After clearing the stored DTC codes with the scangauge, the P0404 TDC is no more! Now I can get back to diagnosing the lack of turbo boost that prompted me to mess with the EGR in the first place...

Typo: That's DTC, not TDC.
 
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