Clanging, jerking, shuddering, surging. Dealer says fine

[huntervangolf]

I have a 04.5 Duramax, LLY. About 2 months ago had the typical harness wear through on the bracket and truck left me dead on the road. Dealer fixed under warranty:).
Now the truck has been jerking, shuddering, surging at low speed, and knocking. Bring it to our home town chevy dealer they keep it all day and tell me its fine and the knocking sound is fuel line sounds:confused:. So I take the mechanic for a drive because he said he couldn't get the truck to duplicate what I described. I get the truck to do it and he roll his eyes and says oh that is just fishing. I ask him what is fishing? He replys you know the feeling you get on your fishing rod when a fish is tapping at the bait:rolleyes:. Get back to the dealer they hand me a bottle of GM fuel injector cleaner and a bill for $250, I tell them I have been running fuel injector cleaner in it already. They reply but this is the good stuff. Of course it didn't do a thing.
Now I have been reading the reports on here for awhile and it sounds like cold weather and this new fuel is not mixing well with our Duramax's. And maybe the dealers aren't willing to take on the problem. Has anybody found a way to fix this problem. Besides changing fuel filters every other week?

[madmatt]

No check engine light?????

[huntervangolf]

No check engine light.

[madmatt]

hummmmmmmmmmm,,,,,tough call via internet.

[DmaxMaverick]

Yes. Tough call.

The one symptom that doesn't fit into the picture is the "clanging". Check for a loose/broken flex plate. Other than that, could be a loose accessory.

The driveability issues could be due to fuel quality and/or gelling/waxing. If changing the filter helps at all, try a different fuel source, and a better cold weather fuel additive. "Fuel injector cleaner" is never the answer for all the symptoms you describe. It may help in some situations, but very rarely. You have too many things going wrong at the same time.

[Mark Rinker]

Also, are you running the winter front during this extremely cold weather? Plugging in the truck at night? Making sure you are burning good quality winter blend fuel?

Diesels in Minnesota winter require some basic planning and participation. The dealerships are not simply not equipped to troubleshoot all problems - knowlege and independence is key...you have come to the right place!!!

[madmatt]

Now that I think about it I did have one come in w/ half the flex plate bolts missing and it was making some funny noises and vibrating pretty bad and at times felt like a miss but there were no codes,,, I spent a while on that one!!!! It idled wierd at times too.

[huntervangolf]

Oh, I'm pretty sure it has to do with the fuel. Yes I have a cold front/cardboard, and plug it in at night. Also I have tried additives. Also have tried different fuel suppliers. It seems to coincide with the temp. In reading all these reports it is becoming pretty obvious to me that the new ULSD / bio fuel is not playing nice with Duramaxes unheated very restrictive fuel filters. What is urking me that it seems many of the dealers are maybe turning a blind eye to it. In previous winters I took way less care and precaution and had zero troubles.

[DmaxMaverick]

......In reading all these reports it is becoming pretty obvious to me that the new ULSD / bio fuel is not playing nice with Duramaxes unheated very restrictive fuel filters......

The filters are heated. Make sure yours is working.

[huntervangolf]

The filters are heated. Make sure yours is working.
REEAAAALLLLLLY! Well there is something I can check. I swore I read on here that they were not heated.
Now this morning (I had it plugged in overnight) I get in start it let it warm up a few minutes. I drive away slowly letting everything warm up. Once I hit the highway I slowly get up to speed and the thing is knocking like crazy, unless I really put the coals to it then the knocking goes away. Once I start giving it just alittle gas it starts knocking again. By the way in my first post (clanging) probably isn't the best discreption. It is a knocking sound.

[Kennedy]

You may have to take matters into your own hands. Dealers cannot be responsible for the fuel that you use. If MN is still doing the B2 thing then you need to treat the bio. If a cold snap is coming, add 10% kerosene or #1 diesel to your tank and drive to mix well. If it gets REALLY cold, use 15%.

I have my own blended B2 in my tank. No blend, just FPPF additives in #2 NON winterized diesel and 2% soy bio. It's good to somewhere around -5°f or so. At some point below that it plugs the filters on my delivery pump. I could treat to a lower temp, but it's not that cold for long, and I fuel when it's warmer, park inside and never really let the truck stand outside overnight.

[huntervangolf]

You may have to take matters into your own hands. Dealers cannot be responsible for the fuel that you use. If MN is still doing the B2 thing then you need to treat the bio. If a cold snap is coming, add 10% kerosene or #1 diesel to your tank and drive to mix well. If it gets REALLY cold, use 15%.

I have my own blended B2 in my tank. No blend, just FPPF additives in #2 NON winterized diesel and 2% soy bio. It's good to somewhere around -5°f or so. At some point below that it plugs the filters on my delivery pump. I could treat to a lower temp, but it's not that cold for long, and I fuel when it's warmer, park inside and never really let the truck stand outside overnight.
I just started using ps(power service) fuel additive. The white container. And had to buy fuel on the road yesterday. Was a winter blend.
I did put in some #1 with additive in it the previous tank fill and it did seem to make a difference. But I have been buying fuel from different vendors trying to see if I could make a difference. I am assuming MN has a 10 - 15% bio blend.

Also how does the filter heater work or how can I check it?

[DmaxMaverick]

......Also how does the filter heater work or how can I check it?

The heater wire is on top of the filter assy, to the rear of the primer pump. With key off, check the resistance to ground (when the engine and ambient temp is cold). I'm not certain what it supposed to be (I'll check later, if necessary), but it should be in the ~1.5K ohm area. If it's open, the element is bad. Once the key is on, or engine running, you should have 12V to the wire. The thermostat for the element is internal to the filter assy, so it should always have voltage when the key is in the "run" position. Check to make sure the harness is plugged in and it is getting voltage. If no voltage, check the fuse.