'00 Dakota 3.9 Liter V6 140k miles, been sitting for 20 months.
I start and drive 1/2 mile and let warm up once a month.
Oil Pressure Gauge started to go to 0 lbs. then back to OK, will repeat.

Finally yesterday got plates and went on 30 mile drive.
After 10 miles @ 55mph Mild Tappet noise, oil gauge would fluctuate to 0 then back up then repeat.

Tappet noise quit after sitting 1 hr.
Then it started again, noise and Pressure gauge.

Put some kind oil cleaner in after 20 more miles, now quart over full.
At first noise was gone but gauge still acting up.
At 15 more miles tappet noise is Louder than ever from other cylinder bank.

Don't make me cry.

 

I bought this truck in Oct. 2010 from a friend that I've known for 10 years when he first bought the truck and I have ridden in the truck quite frequently before I bought it.
When I bought it the truck had no issues except the A/C did not work.
The truck sat since then, except for monthly warm-ups and my 1/2 mile jaunts on my private gravel road.
I didn't take the truck further because I had a DUI and I just got my Driver's License restored.

The truck is in the shop for:

1. State Inspection
2. 4 Wheel Alignment, because I just installed 4 new tires
3. A/C inspection and repair quote.

I was going to have them replace the Oil Pressure Sending Unit, but asked them to not mess with it.

I have the Oil and Filter for an Oil change that I just never got around to performing.
I think that the old Oil has become "Sludged Up" and is what is causing the Pressure sending Unit to malfunction and is causing the Lifter Noise.
Aggravating the problem, I checked the Oil level and I believe it is over full and then I added the quart of Oil Additive.
I believe this maybe causing the Oil Pump to cavitate the Oil and not pump it properly.

I think by changing the old Oil with New Oil to the proper level and a New Filter may cure the problem.

If that does not remedy the problem, I'm going to drain the Oil and replace it with Diesel Fuel.
I'll run the engine to Normal temp then drain it and fill it with new Oil and another New filter.
After 50 miles I'll change the Oil and Filter again,
After 100 more miles I'll do it again and install a New Oil Pressure Sending Unit.
If this procedure doesn't eliminate the Lifter noise I'll replace all of the Lifters.

Your thoughts are appreciated, Thanks.

 

Sounds like your sending unit is working just fine, reporting that you intermittently have no oil pressure.

 

Thank you for your response.
I think the intermittent condition could be caused by partial clogging of the Oil Passages and Pressure Sending Unit or Cavitation of the Oil (Bubbles in the Oil) resulting from being over filled.

I've read that over-filling the Oil causes the Oil Pump to make the Oil foam. Foam or bubbles in the Oil compress unlike pure fluid.

I don't think the Oil Pump is the problem. They either work properly or they fail.

As soon as I get the truck back I'm going put another quart of that Gunk Motor Flush in it.
Then when it's warm I'll change the Oil to the proper level and Filter with some plain 5w30 and run for 50 miles or so.
Then I'll drain that stuff out and replace it with Valvolive SYNpower 5 w30 Synthetic and another new Filter.

Leaving vehicles sit for long periods is the worst thing you can do to them.

 

Actually, driving it half a mile at a time is probably worse than letting it sit.

I have seen low oil pressure caused by a clogged pickup screen. I think that might be your problem.

 

Gunk Motor Flush is a good product as long as your engine is not overly filled with sludge. The danger with using Gunk Motor Flush is it can dislodge too much sludge at one time and can clog up your oil intake and starve your engine of oil.

Did this problem happen after using the Gunk Motor Flush?

Use caution with Gunk Motor Flush

 

The stuff I put in it was 32 oz. Rislone oil treatment.
It stopped the lifter noise until I pulled onto the Shop lot.
The Lifter noise got worse just before I turned it off, after driving 10 miles to the shop to have it inspected.
I bought 32 oz. of Gunk too, but I didn't put that in the engine, just the Rislone.

They just pulled the truck in the shop Friday at 3pm. So I guess they will do the inspection and alignment Monday.
It's 5 miles from my house and as soon as I get home I'm going to change the Oil and Filter.

So you think I might need to drop the Oil Pan and remove and clean the Oil Pump Pick-up Screen?

 

Rislone oil treatment is an oil thickener from my understanding maybe it’s too thick now.

140K is not that much if the engine was kept in good shape and regular oil changes with good quality oil.

I would use the Gunk motor flush only 5 minutes like it says. But MMO is a better treatment to remove any oil sludge because it cleans slowly

No I dont think you need to check the oil pickup from what you said

Start using a synthetic oil way better even for older engines and a good oil filter like Wix or Mobile 1 do not use Fram

 

How about throwing a mechanical oil pressure gauge on the engine and seeing what the oil pressure really is? Maybe before and after your oil change or the GUNK.

 

He said he put it in a shop Friday so Im guessing its getting that done.