SO,

After countless attempts to tune my engine via timing, tuneups, diagnostic work etc, my truck is finally running well. The valves were still sticking, causing a backfire into the intake, very frustrating, and VERY expensive to repair from what I was told by 5 different mechanics. HOWEVER, several little birdies assisted me with trade secrets for this old 3.9. For my 1500 find, I was NOT having the heads redone unless I could do it myself, with the lack of a place to work on the truck, I continued with the following "unfavorable" solutions.

Cost

Plugs, Wires, Cap, Rotor-$100

Reset Ign Timing-$133

Gunk Engine Flush -$4, drove for 20 miles around town to really clean out the motor, I had caked on SLUDGE in the motor visable through the engine oil fill port........valves were getting better, but still at idle had periodic backfires into intake, pop pop pop

Oil change, 15w40 Rotella Diesel Grade oil, &
Sub one qt oil with Marvel Mystery Oil- $30

AFTER 20 MILES driving on the expressway to work and around town.....

THE POPPING IS GONE, SMOOTH IDLE, ITS A SMALL MIRACLE!!!!

I could NOT believe the sticking valve problem was gone, totally shocked, and even more happy a 115K motor isn't toasted from the MORON that owned the poor truck before me, running walmart oil, changing once a year "because he only drove in winter Sept-April" ,he should be burned at the stake!

Anyways special thanks to "Spike" Phil, "Disco" Mike, and "Thunder" Aaron for your time and suggestions......I wish there was a place to make a donation on here, SERIOUSLY!

 

Keep using the rotella and the quart of mmo for 3 short 1000 mile oil change intervals. After the last mmo oil change do a 30 minute flush (at idle no driving) with berryman's B-12 chemtool and then switch to a good snythetic HDEO like M1 TDT 5w40 or Rotella T6 5w40. That should get things nice and clean. Gunk is just kerosene btw, it clean ok nothing great though.

 

Glad to help Lee.
Sorry I have not called you back but my wife is in the hospital, she has been there since Sun.

 

you won't believe it, but that was actually my phone dialing out in my pocket, I picked it up hoping it was someone I talk to all the time, and of course it said Spike Rover!

I was hoping it didn't ring through, but alas the truth comes out

Thanks man, if you're planning a trip around central ohio or Miami Valley Rovers weekend let us know, were always lookin for rover fun down here

 

Spike, I wish your wife a speedy recovery from whatever ails her.

 

Thank you.

 

I've been reading all of the posts (for hours) pertaining to the rough running 3.9 in my 95 Discovery
It has 92,000 miles on it
I'm making a plan for what I am going to do to alleviate the problem
I'm fairly sure the previous owner didn't do much maintenance at all and I myself am guilty for putting regular unleaded gas in it and adding 10W-30 oil to it as I just picked it up today and was planning on replacing it tomorrow when I change the oil, filter, plugs, wires, rotor, cap

From what I've gathered so far, it's important to use the right oil, plugs, etc
I plan on running (5) quarts Rotella Diesel 15-40, (1) quart of Marvel Mystery Oil, Bosch Platinum +4 plugs, Mobil 1-301 filter and following the steps from the above posts

I'm not sure if I'll get the replacement plug wires from the dealership as well as the cap and rotor or if I can find quality parts for cheaper locally


Thanks again to all you guys

 

Fixed :-) and you're welcome Lee.

 

I did not have a sticky valve but right after I got my Disco I decided to put in a can of BG oil flush/engine clean.. forgot the exact name. Per the BG rep I drove it for about 500 miles then changed the oil. You do not want to know the smell of that oil. Ever since it has run like a top. I am at 170k miles. I only use BG products. I just finished changing out my fluid and replacing the tranny filter. Added BG additive to that as well and now she shifts way smoother.

 

Sounds good, I jut put new wires on mine as well, I used the Pro-Line from Rovers North , right at Fifty Bucks, excellent product. Also good price on the y-pipe exhaust metal gaskets.