Hello dakota fans. It's time to swap out the 3.9 from my 96 4x4 dakota. She just burns too much oil. There is a nice sounding 97 3.9 motor available near to me for not too much money. What kind of nightmarish problems am I likely to have swapping a 97 3.9 into a 96 truck. I prefer to keep the 96 computer and harness if possible. Thanks for your time guys.

 

I can't think of anything. The blocks didn't change for ages. Use all the old wiring, sensors and PCM. Might as well drop in a V-8 while you're at it.

 

Thanks, So I do know that the blocks are the same. I take it from your reply that you think it is pretty much a drop in deal. Did the throttle body and injectors/fuel rail change in configuration from Gen 1 to Gen 2/96 to 97? I wonder if I will have to change anything on the intake or sensors related to the throttle body. I guess you think the 97 motor will have substantially the same sensor points as the 96?

I am not thinking about the v8 swap because I am pretty mileage sensitive. I am commuting in the little thing and I do a bit of hunting as well. It is the std cab short bed 5 speed so it's pretty snappy with a v6.

Are these motors known to have any defects like cracks in the heads/oil galleys that would cause excessive oil consumption? It doesn't seem like the mileage alone would be responsible for the amount of oil it consumes. 1t's got 135,000 but uses a quart in about 300 to 400 miles. The funny thing is I don't really notice a lot of smoke. Any input is appreciated. Thanks.

 

It is pretty much identical to your 3.9L engine. I would swap the sensors just to be safe, and highly recommend you change out most of the lower end gaskets so you avoid any headaches later.

If you are losing oil and can't find it, there is a good chance you have a bad plenum gasket on your current engine. Take a peak in the intake and see if it looks like there is oil in there, if so, you may consider changing the plenum and see how it goes. It is a strong running engine and 135,000 is not a lot on it, IMO.

 

Sry Cheetah been away for a couple days. In agreement with Dbilik on the swap over. Use all your old sensors and actuators. Reseal the lower end of the one youre putting in.... the OP gasket and rear main seal. You may have been sucking oil in through the belly pan gasket on the plenum. It was getting atomized so much from the vacuum, you probably wouldn't have seen any smoke.

 

I totally agree with dbilik. You can open up the throttle blades (engine not running) and look down into the bottom of the intake (top of the plenum pan). If you see oil, the plenum gasket is toast. I would do the same check on the engine you want to drop in. If the 'new' engine has a leaking plenum gasket as well, you'll want to take off the oil cap, preferrably pull a valve cover, and inspect for sludge buildup on top of the head. You should also pull the oil pan and see what's going on down there as well. If the new engine has sludge build up and you still want to risk running it, check out the oil pump pickup screen to see if it is clogged up. If so, either replace it or clean it really well. I tried cleaning the screen on mine when it had around 200K miles, and I absolutely could not get all of the carbon/sludge out of every single opening in the screen. That stuff was nasty tough. The carbon sludge wil build up on every surface it touches, and in my case it built up/clogged up an exhaust lifter and killed it.