Hi All,

I've just bought (last weekend) a 92 Dakota LE 4X4 automatic with the 3.9 motor that has 88K miles on it.

I noticed today that the oil pressure gage runs at the bottom limit or just below the normal running range.

So my questions are:

- Does the 3.9 motor have an oil pressure problem?
- Are the stock gages known to be inaccurate?
- Is this normal, and something I should'nt be worrying about?

I love this truck, and hope there isn't a problem.

I appreciate any help and guidance anyone can provide.

Thanks,
Jeff

 

I dunno dude but my oil pressure runs low when the engine warms up so I assume it's common

 

Minimum oil pressure at idle speed with engine fully warmed is 6psi (which is relitively low).
Oil pressure at 3000 RPM should be 30-80 PSI.

The oil pressure on my 3.9L (at least the gauge tells me) is good. At idle, its at least half-way.
My ideas would be:
Get a mechanical oil pressure gauge. This will thread into where the oil pressure sending unit goes (to the right [passener side] of the distributor cap). This way you can see what the actual pressure is. It could be the sending unit is bad.
The oil filter may be clogged. Do an oil change if its been a while (or you don't know when it was last done).
The oil pump pick-up screen may be clogged.
The oil pump may be going bad.

The 3.9L are pretty good engines though. As always, start with the simple stuff.

 

the oil pressure on my dak was low like 10 psi at an idle warm and it took the thrust washer out on my crank and some other bearings. also the sending unit on my was bad but i don't think they was to bad priced...also when you take the sending unit out becarefull because its a tight fit and if you calk the socket sideways alittle bit you'll snap it off...trust me....

 

I bought earlier this year a 1995 dakota ext 4x4 with the 318 in it. About two weeks after getting it the
oil pressure dropped to the bottom of the normal opperating range and sometimes just below that. I talked
to several garages and they said that alot of dakota trucks would do that and to just drive it. coman problem
they said. well after about 7000 miles of me driving it it spun a bearing because of the low oil pressure.

My advice to you is have the pump checked as soon as you can.

 

had my 91 for 5k & it's middle of factory gauge upon start and awhile after, then it's upon idle ...low & below
get going & it's lower end of factory gauge & above
@ idle of about 600 rpm's..........ain't it normal ?

 

Hi All,

The dealer I bought the truck from changed the oil right before I bought it.

Where exactly is the sending unit for the pressure gage? You said to the right of the distributor - is that on top of the motor? There is alot of crap on the back side of the motor.

How hard is it to get to the oil pump, and sump screen - can you get at both by pulling the oil pan?

If getting to the pump is alot of work I may just go back to the dealer and see what they have to say.

Thanks again!

Jeff

 

I would check the pressure with a mechanical guage. You should get 10 psi at idle . On a engine without a guage the idiot light comes on at 7 psi . I have not seen any common problem with the pumps .But some people like to run 20-50 oil. Which maybe good for the motor in some cases but puts a hell of a load on the pump.

 

ok i don't think i got the pic to work...its long black and has a 2 wire plug going into it.....also you have to pull the motor up alittle ways to get to the pan off to get to the pump its a pain,.