Tier 4 and DPF / DOC woes

[Birken Vogt]

I don't know any specifics on this engine. All I know is generalities.

There should be a catalyst right ahead of the DPF. When the engine wants to regen it pumps raw fuel into the catalyst which combusts and gets the DPF hotter than blazes. Then all the soot is supposed to turn to ash.

But the catalyst can be poisoned by an engine with poor oil control. Also if for injectors or some other reason the engine is blowing soot. Nothing will ever work right. These systems are totally dependent on an engine that runs perfectly clean in the first place. Any smoke or slobber and the whole house of cards comes tumbling down. The great part is that the filter masks what you can see by eye so you are left guessing.

 

[wlhequipment]

The DOC is directly in front of the DPF, you're right. I'm only assuming that thing is doing it's job - I have no way to check. I'm also assuming that the ECU injects fuel into the DOC / DPF via simply making the engine injectors super rich, and hoping that fuel makes it into the filter. I don't see a fuel line going to the filter. I see 2 igniters (assuming that's what they are) and 2 air lines (pre and post DPF). Those are supposedly the lines that go to the differential pressure sensor. According to Diesel Forward, there is no indication the engine is running dirty. The more I read about this, the more I find tons of people out there fighting the same fight I am. What a horrible system that allows the whole engine to go to hell in a handbasket if it's not perfect in every way.

 

[Birken Vogt]

Some engines inject fuel on the exhaust stroke, and some have a diesel injector in the exhaust pipe. I don't think there is any other way to do it.

Unfortunately (fortunately?) I don't have any experience with this stuff on a self repair level. They were all still under warranty when I quit working with trucks. And even the manufacturers could not figure it out. Drive it a hundred miles to their shop, they would put it on a computer and do a forced regen, drive it back and the same problems over again.

They don't like to show you what they did if it is a warranty job. So it got bad enough I would tell them to fax us the work order before we came to pick it up. If it said something like "performed forced regen" and they did no other work I would tell them to get out some tools and actually fix the problem not just hook a computer up to it, before we came to get it.

 

[wlhequipment]

The saga continues. I sent the DPF off for cleaning again, and spoke to the diesel shop. The logs indicated the machine asked for a regen in the neighborhood of 10 times, until it just went into derate. So, the operator ignored the machine, run it until it died, and came back to me. Again, this is no surprise. So I took the DOC / DPF off again, and sent it to the shop in DesMoines who cleaned it originally, and they said that it was uncleanable. Damaged beyond repair, must replace, no option etc etc. OK, fine just send it back. I got it back, and here's what I did with it:

I believe I may have actually cleaned it out. It was 100% plugged before, and now, it's significantly more free - breathing. Some of those cells are still clogged, but lots of them are clear. Maybe just maybe if I can make it do a regen, it'll clean itself out, and we're off and running. MAYBE. But, since they ran that engine for so long at full throttle, and that DPF plugged, the intercooler is full of oil from the engine trying to breathe through the turbo, and sucking oil from the seal. So there's that to clean, and now It's burping and farting and spewing out white smoke - classic injector failure (most likely a clogged nozzle). So I have that too. I have to fix those other 2 issues before I'll even try a regen. Stay tuned

 

[8V149 Detroit]

Luckily we only have 1 Tier 4 machine, the rest are a tear in ya eye

 

[Birken Vogt]

There are also several videos of reverse flushing with a pressure washer. From what I can gather it works even better than burning because it actually carries away the unburnable ash as well as the burnable soot. But not a lot of good data on it yet.

 

[wlhequipment]

There are also several videos of reverse flushing with a pressure washer. From what I can gather it works even better than burning because it actually carries away the unburnable ash as well as the burnable soot. But not a lot of good data on it yet.

I saw that, and I was going to give that a try (and still might), but I just can't overlook the opportunity to use fire first

 

[Birken Vogt]

In my experience cleaning things water beats air [fire] every time. What would be really interesting is to see if you could get some kind of tiny brush up in the tubes, because a brush seems to beat just water being sprayed even by high pressure. But that might be taking it too far.

 

[hosspuller]

Here's a thought … If you get the DPF substrate hot enough to burn the carbon. Use the torch to blow pure O2. Naturally, keep the O2 away from any metal parts. Pure O2 and hot carbon should burn away.

Disclaimer: I have no idea of the risks and hazards of this suggestion. Might be a spectacular fireworks show.

 

[tbone1471]

We did the pressure washing on 1. It has worked well for the past 6 months. Saved us 4k for a filter.

 

[DIYDAVE]

Betcha you had a nose fulla black boogers after that adventure! We're from the government, we're here to help you!

 

[Joe Zhao]

Regen does not start because the ECU determines it need an engine oil change. Do an oil-life reset (manual reset so the ECU believes engine oil has been changed). Then restart the machine, let coolant temperature reach certain degrees then regen can automatically start.

 

[DMiller]

Local contractor has three tier 4 units on Lease, they fail they return to dealer, he has no intention of buying anything at this point and will roll leases to next new machines. Dealer remains responsible for all repairs and lost time delays.

 

[John C.]

I've not seen any lease that included basic maintenance and repairs. Most that I have been involved in usually have specific terms that even exclude warranty coverage. Even the long term rental contracts that I've seen require the renter to perform the maintenance. Basically you get to use the machine and make payments with direct expense tax write offs for the same types of repairs with no ownership and no equity in the capital goods. You still get all the head aches that come with ownership.

 

[DMiller]

Somehow the local does base maintenance, all warranty or hard not operator fault repairs are done by dealer. Go figure. Have a 755 series less than year old been back to dealer three times, always get a replacement and dealer has eaten all costs so far.

 

[John C.]

That sounds like a guaranteed cost of operation contract. The owner or lessor has to pay extra for that and it is figured by the number of hours the machine is worked. It's not a bad way to go for new models of machines if your customer base or product can absorb the added cost. The problem is that it only covers so much cost. After it goes over the base range, then the costs are usually shared. I've never found that what we were producing, in most cases coal or trees, had enough profit to risk those types of plans.

 

[DMiller]

Deere replacing Cat on several machines, may have done this just to get back in good graces.

 

[crane operator]

My county got three new dump trucks, and supposedly they have a bumper to bumper warranty, because they were having so much trouble with their new trucks- always back to the dealer. It cost extra, and I'm not sure if its a purchase with buyback, or a lease or a rental, but I remember him saying it was for three years only, and they don't own the trucks at the end.

Of course that's a gov't entity, and while they have a budget, they don't have to show a profit......

 

[wlhequipment]

I thought I had updated this thread with the final outcome. I hate it when people don’t. Yeah I’m one of those. Maybe I started another thread about it. I can’t remember. So... this was a year ago, so some details are a little foggy but here’s what happened. I was never able to clean the DOC / DPF enough to get it to do a regen. Even after my “cleaning” the differential pressures were too much, and you couldn’t even force a regen, which seems like a stupid feature. I didn’t have EST at that time, so I took it to a local diesel shop to get them to force a regen, and they couldn’t either. Joe you’re right about the oil life. That was, if I remember correctly, why it wouldn’t regen in the first place. After the turbo sent oil all through the engine, I put in all new stuff, along with the theoretically “clean” DOC/DPF and sent it to the diesel shop the first time for reset / regen and they reset the oil life and couldn’t do a regen then. That was the first time I sent it there. After the second time, and still nothing, I did get my own EST so I didn’t have to send it there anymore. So, after the second time there , with a supposedly clean DOC / DPF, I got my own EST, and could not get it done either. So, we were left with replacing the aftertreatment, which was something to the tune of 15 grand. My customer didn’t go for that. What he decided to do was reprogram the ECU to eliminate the aftertreatment system altogether. I tried like hell to get him to forget about that option, but he was decided. So the ECU came out, was shipped off for reflashing, and I took off the DOC/DPF and fabricated up regular muffler. That’s how the machine is still running today. Actually is running well. If he ever gets a state or federal job where he’s supposed to have tier 4, he better not have that machine on site. He’s gonna have trouble. This was a total CF, all brought on by a failed turbo, and operators who ignored the regen needed lights on the annunciator panel. Yikes. I’m glad it’s over.

 

[Truck Shop]

Freightliner does have a warranty you have to ask for or buy, most dealers don't say anything about.