We're talking about a Dakota SLT 4WD 3.7Liter 2004 with 150K on the odo. So about 3 weeks ago I noticed my truck was running a little warm (3/4ths of the scale vs half, where it normally is). I got it home and looked at the coolant reservoir and the level was where it was supposed to be so I pulled the radiator cap and the top hose where the cap is was pretty much empty. I topped it off and the temperature was back to normal and I didn't think much of it and just kept an eye on the temps. I checked the oil which was in the normal range. Fast forward 3 weeks. I drove the truck for about 20 minutes around town. During that time while the car sounded like it was running normally I noticed when I got to my destination I seemed to have lost about 1/10th of a tank on pretty short drive. I stopped at the store, the car shut off normally. I came back out 20 minutes later and crank it up and it starts making a horrendous knocking sound immediately. Check the oil. Its about 1Qt low and I notice a little bit of coffee colored slime in the fill neck. I needed to change the oil soon anyway anyway so I just bought a quart of oil and added it so see if I could just limp it to a friend's house where I could legally park it overnight. Restart, it still making a terrible knocking noise with an extremely rough idle. The car will not drive faster than 15 MPH and won't climb any kind of significant hill at all. The longer it runs the worse it sounds until it almost stalls out engine is throwing codes, flashing CEL. I then leave it be and pay to have it towed home.

After towing it home (figuring its probably a bad head gasket from running warm the other week) I ran it in the driveway again looking at the open radiator , coolant is a little low again (inside the radiator itself), but I'm not seeing any bubbles or discoloration at all. I should note too I have not seen any missing coolant in the driveway and the reservoir is still full. So next I drain the oil out and its dark because it was due for a change, but not very overdue. The oil that drained out of it wasn't frothy or light in color like the scum that was in the oil fill neck. I put my scan tool on it at home and I'm getting cylinder 2 and 4 misfire along with P0300. I'm also getting P0462 (Bank 1 cat) P0700 (Transmission Control System Malfunction) and P0562 ((low system voltage) possibly from running rough at low RPM or from the emergency flashers going for an hour waiting for the tow?) I'm waiting for my wife to come home so I can go out and buy some more oil and a filter to change it, so I can run it again and keep combing through it. I'm wondering if that knocking sound I'm hearing might be from a bent or broken connecting rod. I took a short video of it so you can listen in too at idle. Am I just trying to fool myself? Is it as bad as I think it is? Am I missing something? The next thing I'm probably going to do is to pull a spark plug on cylinder 2 or 4 and look for green. Also oil pressure was never observed to be low this entire time. Thanks for any help!

Here is what she sounds like: https://www.youtube.com/watch?v=_aP_...ature=youtu.be

 

Im thinking you tossed a valve lifter arm common on the 3.7 and 4.7

 

Or dropped a valve seat, #2 is common.

 

Thanks for the input! That doesn't make me feel much better lol, but I was unaware of those issues with this model. I'll check into that and update when I know more. Thanks! (Edit: yeah, the more I read about this lifter issue it sounds exactly like what happened)

 

Is it common for this lifter issue to effect the adjacent cylinder at the same time? That's the only part of what people are describing that doesn't match what I'm seeing so far since its both cylinder 2 and 4 throwing codes. It seems like for most people this issue is only effecting one cylinder. I wonder if there is enough clearance for one to knock off the other. Thanks!

 

Update: I haven't touched it again until today. It warmed up this morning and I look under it and suddenly I notice a small pool of ATF under the truck that wasn't there before. I'm going to haul it into the shop this week, this problem is probably above my pay grade.