6.9L running better on atf than diesel ?

[Tarantula]

Hello, I am new here, and like many, I have a question (and unfortunately, a problem). I am having trouble with a 1987 ford 6.9L normally aspirated diesel engine. It is running rough with lots of blue/white smoke and is down on power, my problem started suddenly while driving at highway speed with a fully warmed up engine. I have verified that the engine is receiving enough fuel at the specified pressure, and the fuel is clean and of good quality, I replaced the fuel filter and have replaced fuel lines to the tanks.
I have noticed something while working this issue, and I am wondering if anyone has ever noticed the following: I filled the fuel filter with ATF ran the engine for 30 seconds, and then let it soak. I fired up the truck after about an hour had passed, and the engine was running quite well at idle, almost like a normal diesel should. As the ATF in the filter was used up, and the engine began running pure diesel again, the engine returned to blue/white smoke, missing, barely stay running behaviour. It seems like the ATF might have made the injection pump work properly for a short time? Or does ATF simply have more energy for burning? Maybe a coincidence? Has anyone ever seen this happen before.
I appreciate any responses, further more, I sincerely appreciate the weath of knowledge that has been shared in this forum since it's inception by the members of oilburners. Thanks!

 

[ameristar1]

Welcome aboard! You are definitely in the right place.

Depending on the mileage of the truck, and based on the symptoms, the fuel injection system is due for a freshening up. After roughly 100-150k, the pump, injectors and lift pump need to be done, and the IP needs to be timed properly. Go to the stickies and tech articles and read thoroughly, they'll answer 99 percent of the questions you have.

The ATF has different burn characteristics than regular diesel fuel, plus the viscosity is different, and when it travels through a pump and injectors where the clearances have opened up here and closed up there; well you get the picture.

She's just due. Give Russ (username: typ4) a PM and he'll set you up with a set of matched BB code injectors at a great price (better than most local shops and they are checked and balanced before shipping, no one does that, and yes, the pop pressures can be off on new parts), and Mel (username: Agnem) for a pump. He has a program that can really make a stocker run really strong (called the Baby Moose), and once you get one on that motor, and get it timed properly you'll be impressed. One of the members ( username HammerDown ) has one on his naturally aspirated truck, read what he has to say.

Run a compression check also, just on principle, to see how the cylinders are holding.

There's a product called Auto Rx that works really well in cleaning out the carbon in the motor, and has been known to bring dead cylinders back to life by unsticking the rings. Not a harsh solvent, it's safe and slow. Go check out their website. Do a couple of clean and rinse cycles if the motor has a lot of miles on it and see what happens.

And don't be afraid to ask questions, that's what we are here for.

 

[Tarantula]

Thanks for your input. I have the truck scheduled for a compression and leakback test on the 28th. I am trying to build some faith that I have an IP pump or injector problem vs. something more expensive. The truck was running quite well i.e. 15.5 MPG, very little smoke and only when a diesel should. The engine fires right up even with the rough idle and all the smoke.
One day I am driving down the road and I notice the power is a bit off, and then "BAM" The truck starts running like a dog. I do not know a lot about diesel engines, but I am enjoying the process of learning about them.
I will look into the Auto RX product after I know the results of the compression test. The cost of a new IP and injectors does not bother me as they last for such a long time. I really do not want to rebuild the engine at this time.