I've notice a drastic drop in fuel mileage, and while towing my empty trailer the other day it seemed to be down a little on power but nothing major.
The oil level isn't high, and it's hard to tell if if its contaminated as it is black and runny with no apparent diesel smell.
The last time an injector went, the oil was blowing out of the crank case vent, so that is the sign that I am looking for.
Can fuel mileage drop without the fuel feeding into the oil pan?
Any other suggestions?
thanks

 

It could be your fuel filter or even maybe time for an oil change or air filter.
Usually with a bad injector you will see excessive black smoke and might even puff, puff, puff a cloud of black when idling. Remember that dirty air/fuel filters will cause a drop in mph also.

 

i would check fuel firlter first


common fuel injector problems
is it hard to start. i have also seen idling up

 

Why would a fuel filter drop MPG? Air filter I understand, but the fuel filter?

 

yes , a clogged fuel filter would result in the bad fuel milage , or a drop in fuel milage i should say .

 

I did a new fuel filter yesterday evening. I'll check the air filter and the oil level again today. I'm due for an oil change so I'll do that as soon as I rule out the injector.

 

Air filter indicator was sucked close. I hit the button a couple of times yesterday, but it wouldn't move so I figured it was open all the way. I pushed it again today before I removed the filter top, and it popped back open. Sure enough the filter was filthy. Hope thats the problem.
thanks

 

on my last truck a Dmax,it was usually white smoke that was the indicator of bad injectors. I know because I went through four sets.

 

I already went through 1 injector, and the signs were a sharp decrease in fuel mileage, and then shortly after black oil all over my trailer and underneath my truck with a decrease in power.
I've got a re-usable air filter, but will probably get a new paper filter tomorrow.

 

Dan_K Did the back of your truck look like this?

 

And the street under your truck look like this? This was a sad day.

 

Dude that look has if your oil filter might have loosened up a tad. I had that problem once and was freaking out until I looked at the top of my filter and found that is were the oil was coming from. Also a buddy of mine screwed up his turbo real bad and was leaking from the compressor clamp that holds it to the turbo housing and was also just blowing oil right out of his tailpipe.

 

That will result in a serious MPG drop every time! I think you found your problem.

 

Won't know if thats the problem today as it snowed overnight and I'll be in 4x4 all morning.
Jay,
Thats what she looked like, except I was off to the side of the hwy and 1/4 mile from losing my cell phone signal. My enclosed snowmobile trailer was covered in oil.
Thanks for all the suggestions and help,
DK

 

Dude, you lost an injector(s) if it looked like that. Typically it happens on the 04.5 600 trucks because they were the first model with the 3rd injection event to help with emissions.

An injector will stick open causing cylinder wash down and ultimately filling your crankcase with fuel. Once it gets so full it dumps out the breather and coats the entire underbody with "foil". <---- That's the word we created for the fuel/oil mixture it creates. In fact, I'm wearing my "foil" t-shirt right now. It was the one I was wearing the night this problem happened.

Oh, do not..... I repeat DO NOT continue to drive with this problem. Think for 2 seconds..... what else uses the engine oil to lubricate and cool? Yep, your turbo. My friends truck only went 20 miles with a stuck injector before we figured out what it was. As soon as the oil pressure took a dive we immediately shut it off, called for service, and had a flatbed take it to the dealer.

Upon picking it up from the dealer, 120 miles from home, he made it about another 20 miles and the turbo took a nap. The lack of lubrication destroyed the bearing and consequently caused the compressor wheel to make contact with the housing. It cut a nice little groove in it.

I hope you're still under warranty!