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99 Dakota V6-V8 Engine Swap Project

04-01-2007, 08:04 PM
I have a 99' Dakota 2WD with a 3.9 at 137k miles. I am developing some serious internal engine problems and looking at swapping to a 4.7 or 5.2. Money is tight (in the negatives tight) so I am looking for the most economic way to do this. Heres some questions for you fellows.

WHich motor is a better shot?
Is the V6 model tranny compatible with the V8's?
What about the rear end?
What all externals must be changed (Fuel lines, pumps, gauge cluster)?

Any help would be appreciated. I think my motor is telling me I am running out of time.

04-01-2007, 09:39 PM
Internal engine problems? Like what?

This topic has been covered hundreds of times so do some searching.

04-03-2007, 03:41 PM
They are just like the Durangos,a pain in the butt.Remove the whole front differantal and it will be much get to 3 of the bellhousing bolts,use a 3/8 flex headed ratchet with a short 9/16 socket.I done three Durangos which are the same as the dakotas and are not very fun to change.The book says to remove the transmission,do not do that.The wiring harnesses are differant and possibly the pcms.Do a compresion check on each cylinder first before confirming it is the engine.If you go with the v8 swap,you have to change the transmisson too.

04-05-2007, 02:59 PM
I have a 2000 Dodge Dakota with a 3.9 4wd 5-speed and I got water in the motor and i havent go to look yet but i am pretty sure i have bent rod or maybe worse..but i was wondering how much would i have to go through to put a 318 in it?

04-05-2007, 09:52 PM
The pcm is differant and the wiring harness is differant.The one I mentioned is for the 4wd only.A couple of tips,throw the boot that goes around the crank sensor away,you will destroy a crank sensor that way and leave the crank sensor out when putting in the replacement engine in,put the crank sensor in after the engine is installed.The crank sensor is held in by two 1/4" allen headed bolts

04-08-2007, 11:25 AM
So i will have to replace the computer and wiring harness? What about the tranny will it bolt up?

04-08-2007, 12:09 PM
I believe the 3.9 uses the 904 transmission and the 318 uses the 727.

04-13-2007, 11:10 PM
Alright guys I have been doing some checking around and here is what I have come up with.

1. There are 2 different transmissions mainly used for 90's dodge trucks: the A500 and A518.

2. Although the V6's models come with the A500, and the V8's come loaded with the A518, a V8 can be made compatible with an A500 by adjusting the bands in the transmission. (I am skeptical about the transmission holding up to the torque from the V8, but this information came from what a Dodge mechanic who SOUNDED like he knew his stuff.)

3. Both the A500, and A518 have the same bolt patterns.

4. The A500 and A518 are designed ONLY for the Magnum series engines (3.9/5.2/5.9). The new Powertech engines (3.7/4.7) require a 42RFE (2000 models and up) which is ALL-electronically controlled and is geared differently.

5. Although the 4.7 is new, and more expensive, it puts out slightly more power then the 5.2 and gets better gas mileage. (although it does not have any long term data)

6. Swapping from a Magnum series to a Powertech series is considerable more complicated as apposed to swapping Magnum-Magnum. As you must not only change the transmission but many other components. (fuel systems, possibly cooling system)

7. Any and all engine conversions require ECU and wiring harness's to be changes. Also torque converters.

I would have to say at this time my best bet is finding a donor truck (salvage with usable engine, trans, etc.) and swapping part by part.

To all of you who mentioned previous threads of this topic, thanks for your advise, I have seen them, I felt like starting this one to give more specific information and questions.

Heres my unanswered thoughts that continue to keep me up long hours into the night.

Does the Powertech series (year 2000+) and transmission use different dimensions that would prevent me from converting?

I have found NO information about compatible rear end applications? Anyone who knows anything about dodge axle's, differentials, etc. let me know what you think.
Again I am trying to swap from a 3.9 to a 4.7 or 5.2.

I have done a lot of talking with tech's but here's some of the links for info I have found online:

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Thanks for all the info keep this thread going!

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