Hello there. I have a Dodge Dakota that I'm working on right now, with an issue that leaves me stumped.

2000 Dodge Dakota SLT 2WD
3.9 V6
Automatic
202,000 on I assume the original engine.

I'll be driving it, suddenly the oil pressure drops to zero, check gauges light comes on. Shutting it down and starting it back up sometimes brings oil pressure back.

It's not the sending unit.
The oil level is full with fresh oil.

I am actually losing oil pressure. I know this because if it stays at zero for too long I start hearing the lifters tick.The lifters also tick briefly when starting the engine from cold, then I get oil pressure and all is well. I also replaced the sending unit just to be sure.

I managed to get the issue on video:
https://www.youtube.com/watch?v=VfQu...ature=youtu.be
(And my niece is disappointed because Uncle's truck is being mean and not letting her go to the park)

I suspect something is causing the oil pump to shut down, but I don't know what. That Check Engine light just shows a trouble code for an oxygen sensor. I'm stumped as to where to go from here. Hoping you guys can help.

 

Welcome to the forum.

Start by putting a mechanical gauge on the engine to see what you actually have for oil pressure. That'll give us an overview of the engine condition.

How long have you had the truck? Could there be sludge, etc., in the oil pan that is clogging the pickup?

 

I think that clicking of dry lifters that goes away when the pressure comes back up is a pretty good indicator that I am actually losing oil pressure. That and I replaced the sensor by the distributer cap for good measure.

I bought the truck used, and the oil in it was pretty dirty. It sat throughout the winter, with me occasionally starting it to keep the battery topped off. I changed the oil before putting it on the road.

When I bought the truck I test drove it and it behaved fine. Then I parked it for three months because the heater core was bad (just got that fixed).


Oh yeah. It took hours for this thread to appear. Is that some kind of spam protection or was there a server glitch?

 

Sounds like you may have heavy sludge buildup we had another post with the same problem he took a valve cover off to a very heavy sludge problem.

Pull a valve cover off and have a look

 

And here I was hoping it was simple like a bad relay or something... which come to think about it doesn't make sense because I'm pretty sure the oil pump is purely mechanical.

Sludge build up also doesn't entirely make sense because the oil pressure drops are random and seem to occur after the engine warms up. When it has pressure, the readings are normal. They go from normal to dead zero. Could be the gauge is a simple idiot light but I think 2000 is too early for that.

I'm going to take it to a reputable mechanic I know. Yes it's going to cost me but while I know the 3.9 pretty well I don't want to go pulling the oil pan, valve covers, cutting my hands on something, misplacing the socket I need, and hoping I don't mess something up and cause more headaches for myself.

 

The pickup type has rubber "O" rings. At least last time I did an oil pump, where the screen/pickup
tube mount together. If the o Ring are bad, you will
Lose pressure. But it sounds like pump failure to me. If it's heavily sludge it will cause the pump to fail. New oil pump.

 

This guy had the same thing going on like your problem good then zero pressure when he finally did pull a cover it was shock time and he did an oil change also but when he pulled the new filter later it was clogged solid with sludge.

Pull a cover get it over with

Oh and it was so bad he replaced the engine

 

Looking at the video I think whats happening is the oil pickup is getting clogged up when you shut down the muck stuck to the pickup tube drops off the screen and you get oil flow again.

Your pan is probably full of oil muck

 

Okay, so it was sludge in the oil pan.

Shop cleaned that out and put a new pump in.

Then I discovered crap in the driver's side valve cover so I pulled that and cleaned it as best I could. Fresh oil and STP oil treatment and so far so good. Valve cover's not leaking so I think I did it right. Drives fine.

Fingers crossed for this engine. I just do not know. 3.9's are hard to kill but I don't know what abuse this suffered at the hands of the previous owners. I'll be kind to it and we'll see.

 

A good detergent oil would be a good thing or a 100% synthetic oil they clean old oil goo well.

I would also change your oil and filter 2 or 3 times in the next 12 months good cheap insurance to keep your engine running.

$75 max for oil and filters or $1500 for a rebuilt engine