I have a 2002 dakota 3.9 sxt.

Just a few days ago I noticed some sort of knocking and hesitation in the engine when trying to accelerate shortly after starting. Then today it happened again and realized the oil gauge kept going down to L then almost up to H and it just kept going up and down as I drove. If I was idling it went down to L; accelerating and it would go up to middle/H.

Checked oil and it seems to be fine.

Any ideas before I bring it in to the shop?

 

If you're getting a rod knock, going to a shop won't do much for you. All they can do is put a mechanical gauge on the oil port next to the distributor and verify you have minimum 8-10 psi of oil pressure at idle and 30 psi around 2500 RPM.

 

Not 100% sure it's rod knocking.

I assumed I could bring it to the shop and they'd let me know what's wrong with it for sure.

How would I go about diagnosing it on my own then?

 

Knocking is knocking and little of it can be diagnosed without pulling the motor at least partially apart. Starting point is pulling the valve covers off and making sure the valves are all opening and closing uniformly and that you don't have a bent pushrod or collapsed lifter or worn down cam lobe. Only way to check cam bearings is pulling the intake and timing cover and pulling the cam out. Last option is rod bearings, pull the pan off and inspect. Even then, there's an underlying oil pressure issue causing the knock. Before too long you'll likely spin a bearing.

 

I have no idea how to do any of that ha ha, so I think I'm just going to bring it in and see what they say.

If it ends up being a rod knock, does that mean the engine is shot?

 

Is the engine shot as in it should be taken apart and rebuilt? Yes. Is it shot as in you need to use it for a boat anchor and buy a whole new one? That'd be your decision.

Let that rod knock go long enough, though, and you CAN get to where it's not your decision which way to go, but it's either a whole new motor or a whole new truck.

RwP

 

and being the 3.9, if it's indeed rod knock, you'll be in a pickle. Pretty sure the 3.9 rods are not offered many places, most people get a set of 318 rods and take them to a machine shop and say "mill these down to match the stock one". I think there's a 1/8" difference in rod width that has to be cut off and chamfered.

 

Well I brought it in to the dealership and they said they couldn't find anything wrong with it. Ughh.
So they checked the oil, it was good. Changed it anyways along with an oil filter.

Drove it down the street back home and right away I felt it again.
It's more of a clunking sound, with hesitation in the motor and loss of power when trying to accelerate. Maybe a fuel issue idk.

I guess I'm just going to have to drive it until something serious happens, if it even is that serious.

 

first mistake was dealer. Second mistake was them not driving it or doing a live sensor scan on the DRB. Alot of the time, we have the customer take a tech for a test drive at work to tell them exactly what they hear or feel.

Are you sure it's firing on all 6 holes? What you describe could almost be a dead hole, but it would be shaking like a SOB, similar to an odd-fire V6. Granted that an even-fire V6 still has horrible harmonics.

Is your engine light on? What codes? Do the keydance if you dont have a way to pull them.

 

Yea the tech drove it around the lot I believe and said he couldn't replicate it. It's one of those things that is hard to describe and you have to experience it to understand. I tried my best to describe it to them.

It says "Completed check of concern - no dtcs in system - checked oil level ok, changed oil and taken sample - no bearing material - unable to verify condition - may be bearing clearance issue when engine cold, causing oil pressure fluctuation - hesitation not duplicated."

No codes or anything.

Not sure if it's firing on all six. No shaking real bad either, but right before the power starts to stutter I can feel some kind of clunking somewhere in the rear end. Oil gauge is 3/4 to H also.