Dodge 3.9l V6 engine reliability?

Oct 30, 2002
Great Lakes
Not sure about the specific designations, but it's an engine that was fitted in 2003 Dodge Dakota among others (probably in Durango as well).

Are there any known issues with this engine or the auto tranny that goes with it? Is 130k-150k miles considered to be a lot for it? What are the typical things that may need attention at such mileage?
A friend of mine who goes through cars has a 1999 Dodge Dakota 3.9L, it has about 140k on it. He bought it used with around 110k on it, says it's been the most reliable, best vehicle he's ever had. Since he had it's needed a fan clutch and a radiator (the radiator was plugged in the lower 1/3 with some sort of deposits that dissolved in vinegar), and a power steering pump.

Since he bought it used it's impossible to say why the radiator got clogged, my guess is that it had a leak and was continually topped up with water.

His truck is a manual. I would not think 150k to be a lot for this engine.
The older ones had issues with pinging that were pretty hard to compensate for. Something about an oil leak in the valley...

Had a 92 dakota with this 3.9 briefly, ran like a scalded cat.

Dodge 4+ speed RWD automatics, OTOH, don't hold up.
The automatic will need TLC to last. New fluid, filter, and a flush would be in order. Those engines seem to hold up as well as their big brothers, the 5.2 and the 5.9 My dad still has his 92 Dakota with a 5.2 and 4WD. I think the only thing that will stop that thing is the rapidly advancing rust on the underbody and frame. (in Cleveland, OH) That truck is a tank.

For the pinging issue, he complained about having to run high test, so I made a water vaporizor that basically puts some extra humid air in the mixture, and he switched to 87 the same week and ever since without any pinging.
Originally Posted By: eljefino
..Had a 92 dakota with this 3.9 briefly, ran like a scalded cat..

I had a 1993. Same deal.

Blown plenum gasket is very common. Same problem the 5.2 and 5.9L Magnum engines. 98-01 are most common. Gasket was redesigned but can still fail. Pinging and oil consumption are common when this happens.
Honestly the 3.9L is NOT my favorite engine. I find them very underpowered, they always shake like they have a dead cylinder and the MPG isn't great. MPG is about the same as the 5.2 but less power...
A buddy of mine has one in his Dakota. Kinda underpowered, pig on fuel, uses more gas than my Expedition.
Ive got a 1999 Dodge Conversion van with the 3.9 V6. Had it since new. I did have pinging issues as well, 89 octane solved that problem, atleast for me. I have 153,000 on it and it runs great. I've done 2 Auto RX runs in it recenty and it really cleaned up the rings and bumped up the fuel economy. I've flushed and filled the tranny atleast 6 times over the years to keep it going. Yeah, its not the most powerful engine but I can't complain, she's been good to me, my wife ran ours all over the east coast.
If my memory is correct the colder plugs are Autolite #3923. The electrode doesn't stick into the cylinder as far. I had the pinging problem since new in a 2001 Ram 1500. The plugs solved the problem and I could run 87 octane all year. It would only ping in cold weather with the standard plugs. It didn't burn any oil, so I'm thinking the pinging and intake issues are separate. As far as reliability, we used them as company vehicles until they had at least 150K miles and they all held up well except for one trans failure. That trans will hold up well with the correct maintenance. Band adjustment and fluid/filter changes every 30K.
Hey, so I know this is an extremely old thread, but if you happened by it like I did in a simple Google search, let me tell you a few things about my little ol Kota.
Its a 2000 3.9L 4Spd Automatic.
It does have a check engine light on, but it is not causing the truck to run abnormally, the code is P0601 Which is a Check Sum Error, meaning at some point in this Truck's rough life, it had a few too many power surges that fried an unimportant part of the ECM.
Anyways, so this ol 3.9L is a tough V6. It may not be quick, but it will run its butt off!
It had, and I do say HAD some major oil leaks coming from the various gaskets, Timing chain cover, valve covers, and oil pan. But it's honestly as simple as buying new gaskets and putting them on, and you dont need to be a mechanic to really do that, but I would suggest you get one for the timing chain cover only because of its location.

I normally run just Regular unleaded ethanol gas, and about every 4th or 5th tank, I'll run higher octane with a fuel stabilizer in it, not really necessary, but its a habit I carried over from my old 82 Chevy.

Every thing still works, all lights all sensors, I mean, the radio has been replaced but who hasn't replaced their old stock radio?

I have yet to have it break down on me, save for the few times I thought I could make it to the gas station.

The only thing I have had to replace on it thus far is a couple of light bulbs, spark plugs, tires, brakes, and the fuel pump.
But honestly, that's just regular maintenance things.

I do recommend replacing the stock muffler on it for a muffler that is a bit more "open". Since doing so, it has actually had a slight increase in power, and when I hooked my OB2 Scanner in, then took it for a road test, my fuel economy increased by roughly 1-2mpg. I know that may not sound like much, but in the long run it does make a difference.

This is my first Mopar I have ever owned, and I've got to say, I have completely fallen in love with this machine.

It rides smooth, it doesn't rattle like you'd expect a 20yr old truck to do.

My only real complaint about my Dakota is, it has been severly abused and the body has some ugly looking dents. Oh, and that 1 Tire Fire is slightly annoying at times, I understand the function of it, but sometimes it gets me stuck on wet and muddy dirt roads.