DEF Pump dead, decisions decisions ....

[chri5k]

My 2016 2500 CTD has 125,000 miles on it. The other day the "Service DEF System" message appeared and the code was 20E8. There was an old one stored from when the truck had 289 miles on it and new one according to AlphaOBD. I reset the code but the message and the code came back after a few minutes. Filled the DEF tank in case the level sensor was bad and it was really empty. No joy. Looks like it needs a new pump. They are not hard to replace but the pump is $1,300. I can do a full delete for $1700. I put up a poll on which way to go.

One wrinkle, the truck has NOT gone into limp mode yet but it is threatening to in 140 miles. Does anyone know if an MM3 with delete tunes will stop it from going into limp mode if I do delete?

 

[tjfdesmo]

I think Rock Auto(?)showed an aftermarket DEF pump for much less money.

 

[Gr8bawana]

I think Rock Auto(?)showed an aftermarket DEF pump for much less money.

Less than $400 on Rockauto.com.

 

[chri5k]

Thanks for the suggestion but that is a rebuild service only on Rock Auto. They will send you instructions on mailing it to Cardone. Takes 4 - 8 weeks after they receive it. This is my daily driver so renting a replacement vehicle is about $250/wk so not really saving anything over a new pump. There is a company on Ebay that has the rebuilt ones for $600 plus $50 overnight shipping and I can get it August 10. That plus a weeks rental is ~$900 and I'll have a rebuilt pump.

Curse this emissions crap. Luckily, I was not in the middle of no-wheres-ville pulling a trailer with my horses. This would have been a disaster.

 

[Sandevino]

Is this a common failure or something you can attribute to bad DEF?

 

[chri5k]

IDK about common but the pump rebuilder is backed up with orders. May be COVID related. I have always used Peak Blue DEF and I check the date codes to make sure it is fresh. I drive about 25K - 30K miles per year so the DEF does not sit in the tank unused. The message to service the DEF system came on shortly after 125,000 miles. I thought it might be one of those mileage based reminders like servicing the EGR on pre-DEF trucks or the CCV filter. About 3 days later the CEL came on. I cleared it a couple of times but it came back in like 5 minutes. Today the dreaded 150 miles until 5 MPH message appeared. I did notice the exhaust had a very strong ammonia smell that stung my eyes. It normally smells kind of like pool water in an indoor pool.

 

[Sandevino]

Are you positive it’s the pump and not the control module?

 

[chri5k]

Not 100% but the DCU failure is a different code from what I have been able to ascertain. My understanding is this code appears when the DCU commands the pump to prime for an injection event and it does see 130 psi within 45 seconds. There are different codes for pressure sensor and pump motor circuit open or shorted. I checked all the wiring and it all looks and feels tight. Unseated and reseated all the connectors. The pump test in AlphaOBD fails with an unknown error. The DEF pressure sensor is built into the pump assembly so it could be that as well but it is serviced with the pump.

 

[Travelin Ram]

Your future plans for the truck are a factor. No dealer will want it deleted and some shops won’t even work on a deleted truck.

My .02, after 4 pre DPF diesels and two with DPF is I’d stay stock. I have the 6.7 in a Freightliner and I would never consider deleting it. It gets better economy than it’s predecessors, and it sure is nice to arrive at my destination without black soot all over what I’m towing.

 

[superjoe83]

There are some tuners out there that will do an emissions intact tune which will turn off the egr and scr system but leave the dpf intact and functioning normally

 

[chri5k]

8/2 Update

Dug into this a little more since I just have to know. I reset all the codes with AlphaOBD. I disconnected the DEF line at the injector and used AlphaOBD to do a pump override test. To my surprise, I heard the pump run and DEF came out of the hose. After a few moments the CEL came on and the test stopped. Read the fault code and it was the same, 20E8. This seemed to indicate the DEF control unit was functioning properly. I thought maybe the injector was stuck open with crud or something not allowing the pump to build pressure. I have a new injector that I keep handy and attached it to the DEF line and electrical connector. I cleared the codes again and re-ran the DEF pump test and I could hear the pump running but it sounded like it was cavitating or something where it would try to build pressure, drop off and try to build pressure repeatedly. No DEF came out of the injector, the CEL light came on and the test stopped. The 20E8 code was set. I cleared the code one last time and decided to pull the pump.

The DEF tank had about 3 gallons in it so I siphoned it out by taking off the fill pipe where it enters the tank. I siphoned it into a clean clear plastic container. I did not observe any discoloration or crud in the DEF. It was crystal clear. Once the tank was empty the electrical and DEF line came off easy. The electrical has one of those tabs you have to slide up before you can squeeze the release tab. The DEF line has a semi-circular locking ring that looks like a circlip. Squeeze the ends together to release the locking ring. When you pull the line off be careful there is a metal restrictor in the pump outlet that may fall out. It is about 1 inch long with a small hole in it and looks like it is made of stainless steel.The pump assembly is held into the bottom of the tank with a large locking ring. I guess the dealer has a huge spanner wrench to loosen it. I put a pry bar in one of the outer notches and hit it with a 16oz multi-directional force generator. That ring is a ***** to get loose since the tank slides around in its mount. I had to up my game to a 2.5Lb multi-directional force generator. After beating on it for a bit, it let loose. Beware there is about a quart of DEF in the bottom of the tank that will give you a shower. Make sure you are not directly beneath the pump when loosening the lock ring. I cleaned out the remaining DEF and wiped down the inside of the tank with clean whit shop towels. The towels came out wet but clean. I don't think there was any contamination in the tank.

So now it sits and waits for a rebuilt DEF pump. I found a vendor on Ebay that has them in stock for $598. There is a $50 core charge in the $598 so net cost is $548 when you send the core back. I paid for overnight shipping so It should be here early this week. I think I will send mine out to the Cardone rebuild service through Rock Auto instead of getting the $50 back. That way I will have a rebuilt pump on hand for next time.

To be continued ....

 

[Gr8bawana]

Following this one.

 

[Sandevino]

8/2 Update

Dug into this a little more since I just have to know. I reset all the codes with AlphaOBD. I disconnected the DEF line at the injector and used AlphaOBD to do a pump override test. To my surprise, I heard the pump run and DEF came out of the hose. After a few moments the CEL came on and the test stopped. Read the fault code and it was the same, 20E8. This seemed to indicate the DEF control unit was functioning properly. I thought maybe the injector was stuck open with crud or something not allowing the pump to build pressure. I have a new injector that I keep handy and attached it to the DEF line and electrical connector. I cleared the codes again and re-ran the DEF pump test and I could hear the pump running but it sounded like it was cavitating or something where it would try to build pressure, drop off and try to build pressure repeatedly. No DEF came out of the injector, the CEL light came on and the test stopped. The 20E8 code was set. I cleared the code one last time and decided to pull the pump.

The DEF tank had about 3 gallons in it so I siphoned it out by taking off the fill pipe where it enters the tank. I siphoned it into a clean clear plastic container. I did not observe any discoloration or crud in the DEF. It was crystal clear. Once the tank was empty the electrical and DEF line came off easy. The electrical has one of those tabs you have to slide up before you can squeeze the release tab. The DEF line has a semi-circular locking ring that looks like a circlip. Squeeze the ends together to release the locking ring. When you pull the line off be careful there is a metal restrictor in the pump outlet that may fall out. It is about 1 inch long with a small hole in it and looks like it is made of stainless steel.The pump assembly is held into the bottom of the tank with a large locking ring. I guess the dealer has a huge spanner wrench to loosen it. I put a pry bar in one of the outer notches and hit it with a 16oz multi-directional force generator. That ring is a ***** to get loose since the tank slides around in its mount. I had to up my game to a 2.5Lb multi-directional force generator. After beating on it for a bit, it let loose. Beware there is about a quart of DEF in the bottom of the tank that will give you a shower. Make sure you are not directly beneath the pump when loosening the lock ring. I cleaned out the remaining DEF and wiped down the inside of the tank with clean whit shop towels. The towels came out wet but clean. I don't think there was any contamination in the tank.

So now it sits and waits for a rebuilt DEF pump. I found a vendor on Ebay that has them in stock for $598. There is a $50 core charge in the $598 so net cost is $548 when you send the core back. I paid for overnight shipping so It should be here early this week. I think I will send mine out to the Cardone rebuild service through Rock Auto instead of getting the $50 back. That way I will have a rebuilt pump on hand for next time.

To be continued ....

Great troubleshooting and very well documented. I’m genuinely intrigued why parts fail and am curious to know what happened here.

 

[chri5k]

Sandevino. I tried to open the pump. There are 6 locking clips that hold the bottom on. You can see one of the clips between the electrical connector and the DEF outlet and another behind the DEF outlet in the first picture. I put a piece of wire under each clip to hold it open but I still could not take off the bottom cover. I don't see any obvious screws and none of the labels feel like they have a screw under them. I guess there might be some sort of glue or potting under the cover but that will be for the rebuilder to deal with since they have done many of these. From what I have read these things have various valves and check valves in them to prime, create and hold pressure. The electric motor is working since I hear it whirring and the pump will put out a bit of fluid when it has no restriction. It just won't build pressure. Probably some $0.50 check valve gone bad causing the failure of a $1300 (New) or $600 (rebuilt) pump. Not the best engineering since this thing is the DEF quality sensor, heater and level sensor in addition to the pump. So if any one of those fails you have to replace / rebuild the whole unit. Below is a stock image of the pump. Looks like a short fat squid. From what I can tell, the ********* thing in the center is the heater, the red tentacles are the DEF quality sensor fingers that hook to the white wires and the greenish white thing sticking up is the tank level sensor. The pump is on the bottom.

 

[Sandevino]

I’ve not had one fail yet (fingers crossed) on any of my Peterbilt’s one of which has over 450k miles and counting. I’m sure there’s a difference between commercial and light duty DEF pumps, but I’d like to see Ford, Ram and GM get their act together.

 

[chri5k]

The commercial Cummins pumps are metal and usually have a offset metal pumping mechanism. The other parts like level sensor, gauge and heater are also separate units that can be replaced separately if they fail. It is this whole all in one thing and being made of plastic that I think causes the issue. I have seen where the level sensor or heater fails so the whole unit needs to be replaced. Kind of sucks that if one of the four components fails the whole $1300 assembly needs to be replaced. I guess it is cheaper to make it all one plastic unit and also only one "assembly" to put together on the assembly line.

 

[SouthTexan]

I would try to run some vinegar and distilled water through the pump before getting a new. DEF tends to crystallize and seize pumps/floats especially if is of low quality or past its shelf life.

 

[chri5k]

I have heard that statement before about DEF crystallizing in the system but have not found any solid literature on the subject. When the water evaporates from the DEF solution, it leaves a white residue that looks like snow. It would seem unlikely that significant evaporation would occur at the bottom of a 5 gallon sealed tank tank containing 3 gallons of DEF. As mentioned above, I drive the truck about 30K miles per year so it is driven nearly every day. I buy Peak Blue DEF and check the date code to make sure it is still good. When I drained the tank the fluid was clear with no deposits in it.

The only solid literature I have found on DEF decomposition is on this page. https://www.capitalremanexchange.com/20-facts-you-need-to-know-about-diesel-exhaust-fluid-def/ DEF breaks down or reduces to Ammonia and Isocyanic Acid: (NH2)2CO → NH3 + HNCO in the first phase. In the second phase the Isocyanic Acid chemically breaks down with water into Carbon Dioxide and Ammonia: HNCO +  H2O → CO2 + NH3 overall which is this: (NH2)2CO + H2O → 2NH3 + CO2. None of those are solid masses or crystals. After that there a two more phases that require high temperature and a catalyst to break down the NOx. That same page also talks about evaporation "For example it would take over two years a constant rate of 125 degrees F for the DPF to turn into ammonia and evaporate. However any temperature over 86 F you risk some evaporation due to DEF being almost 2/3 water." Again no solids are produced by the decomposition.

I think the whole "DEF crystallizes in the tank ..." thing is made up by dealer service writers when they don't know why a component in the DEF system failed. I worked in dealership as a mechanic for 8 years and the BS a service writer will tell a customer is truly astounding.

 

[SouthTexan]

I am just going by what my field technicians have done when the same thing happened to the medium/heavy duty trucks we service. It would crystallize or get crystallized DEF sediment in it when the operator rate the tank too low which mainly happened out on location in the oilfields. A few of my technicians would carry a gallon of vinegar and several gallons of distilled water on their trucks at all time because of this.

 

[Senodil]

It seems like 90% of the failures are emissions related..... If your going to keep your truck for a while delete it, this rebuilt $500 pump is 1/3 the cost of a delete. If your the guy who wants to have a newer truck every few years toss as little into it as you can until you part ways with it.