Oil Light
 

Hi, I drive a 1991 Plymouth Sundance RS 2.5L 4 cyl TBI with 202,000
miles. The engine is well-tuned and pretty smooth. I'm running with
10W-30 full synthetic oil and Napa Gold oil filter. Oil is pretty
clean. Here's my dilema:

Oil light on when hot at idle

Basically, the oil light comes on when I stop at a red light and shuts
off when I accelerate. This only happens after the car is fully warmed
and has been driven for a while. The light usually goes on when RPM's
get below 800.

Are there any worries? Anything to check?

Have thew true oil pressure tested with a mechanical gage tapped into the
block where the oil sender is, then you will know the general condition of
the engine's internals, regarding oil pressure.
> wrote in message
oups.com...
> Hi, I drive a 1991 Plymouth Sundance RS 2.5L 4 cyl TBI with 202,000
> miles. The engine is well-tuned and pretty smooth. I'm running with
> 10W-30 full synthetic oil and Napa Gold oil filter. Oil is pretty
> clean. Here's my dilema:
>
> Oil light on when hot at idle
>
> Basically, the oil light comes on when I stop at a red light and shuts
> off when I accelerate. This only happens after the car is fully warmed
> and has been driven for a while. The light usually goes on when RPM's
> get below 800.
>
> Are there any worries? Anything to check?
>
>



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I just put an oil pressure gauge on there (used T-Fitting to fit gauge
and oil light switch on engine) and went driving around for a little
while. After driving for about 20 minutes, I noted the following
readings on my oil gauge:

Hot Idle (in drive): 17 Pounds
Hot Idle (in Park): 24 Pounds
2000 RPM: 40 Pounds
3000 RPM: 50 Pounds
4000 RPM: 60 Pounds

My observation is that my oil light (the teapot) seems to kick on when
my gauge gets below 18 Pounds.

Is 17 Pounds of pressure at hot idle ok?

How many pounds pressure is supposed to kick on the teapot light?

wrote:
> I just put an oil pressure gauge on there (used T-Fitting to fit gauge
> and oil light switch on engine) and went driving around for a little
> while. After driving for about 20 minutes, I noted the following
> readings on my oil gauge:
>
> Hot Idle (in drive): 17 Pounds
> Hot Idle (in Park): 24 Pounds
> 2000 RPM: 40 Pounds
> 3000 RPM: 50 Pounds
> 4000 RPM: 60 Pounds
>
> My observation is that my oil light (the teapot) seems to kick on when
> my gauge gets below 18 Pounds.
>
> Is 17 Pounds of pressure at hot idle ok?
>
> How many pounds pressure is supposed to kick on the teapot light?
>

Probably less than that. I've heard that a good rule of thumb for
*most* engines is 10 PSI for every 1000 RPM.

nate

--
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> wrote in message
oups.com...
> I just put an oil pressure gauge on there (used T-Fitting to fit gauge
> and oil light switch on engine) and went driving around for a little
> while. After driving for about 20 minutes, I noted the following
> readings on my oil gauge:
>
> Hot Idle (in drive): 17 Pounds
> Hot Idle (in Park): 24 Pounds
> 2000 RPM: 40 Pounds
> 3000 RPM: 50 Pounds
> 4000 RPM: 60 Pounds
>
> My observation is that my oil light (the teapot) seems to kick on when
> my gauge gets below 18 Pounds.
>
> Is 17 Pounds of pressure at hot idle ok?
>
> How many pounds pressure is supposed to kick on the teapot light?
>
>
17 at idle is low, 30 would be better. Sounds like a well worn engine.
You might try running a bit heavier oil if you don't want to tear it
down. 20W 50 would probably do wonders.


--
Steve



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Are my bearings shot? Do these oil pressure readings mean that I need
new rod/main bearings?

My oil pressure at driving speed seems to appear to be good, though,
and it seems to go up by at least 10 pounds for every 1,000 RPM (which
is what the specs state). Oil pressure stays at about 50 Pounds while
cruising the highway.

A compression test was done on the engine 2 months ago. Mechanics said
that engine compression is good and even. Results was about 155 PSI
across all 4 cylinders. Engine doesn't burn any oil. There is no blue
smoke from tailpipe. Engine leaks only less than 1 quart of oil every
3,000 miles (mainly due to leaky valve cover gasket). Other than that,
oil consumption is very minimal. Engine still has pretty good power.
Are those things (good compression, low oil consumption) good signs
that the engine may not actually be that badly worn?

BTW, I had the head gasket replaced over 6 months ago. A valve job was
also done as well while the head was off.

Overall, I wonder if the sensor for the oil light is acting flaky and
causing the oil light to come on at the wrong time.

On 24 Jun 2005 19:52:55 -0700, wrote:

>
>Overall, I wonder if the sensor for the oil light is acting flaky and
>causing the oil light to come on at the wrong time.
I don't know your particular engine but it seems to me 17 at hot idle
ought to be good enough. I had an old Jeep that showed less than
5psi on it at hot idle and ran it for years and years that way.

Get yourself another sending unit They are pretty dang cheap and
certainly worth trying. Hopefully one of the smart guys here will
pipe up and tell you what the specs are for oil pressure on your
engine.

Steve B.

On Fri, 24 Jun 2005 wrote:

['91 Sundance 2.5TBI with 202k miles, recent head gasket and valve job,
155 pounds in each cylinder, 17 lbs oil pressure at idle and 60 lbs at
4krpm, 10w30 synth w/NAPA Gold filter]

> Overall, I wonder if the sensor for the oil light is acting flaky and
> causing the oil light to come on at the wrong time.

That is the first place to focus your efforts. After awhile (and 200k
miles counts as "awhile"), the sender can go off calibration. A new one
can be had for not much money from NAPA or the dealer.

17 lbs at idle is not what you'd see with a new engine, but it's
acceptable. The suggestion to switch to 20w50 engine oil (or 15w40 heavy
duty) is probably a good one. Another possibility is that your oil
pressure relief valve is stuck midway between "open" and "closed". If
you're not getting unseemly knocking noises from the engine, and with your
excellent oil consumption and compression figures, your rods and mains are
probably fine, though at this mileage with that engine, yours would be one
of the few *not* to be setting up a hell of a racket with gudgeon pin
knock. My '92 was another of the few.

DS

Steve W. wrote:

> > wrote in message
> oups.com...
>
>>I just put an oil pressure gauge on there (used T-Fitting to fit gauge
>>and oil light switch on engine) and went driving around for a little
>>while. After driving for about 20 minutes, I noted the following
>>readings on my oil gauge:
>>
>>Hot Idle (in drive): 17 Pounds
>>Hot Idle (in Park): 24 Pounds
>>2000 RPM: 40 Pounds
>>3000 RPM: 50 Pounds
>>4000 RPM: 60 Pounds
>>
>>My observation is that my oil light (the teapot) seems to kick on when
>>my gauge gets below 18 Pounds.
>>
>>Is 17 Pounds of pressure at hot idle ok?
>>
>>How many pounds pressure is supposed to kick on the teapot light?
>>
>>
>
> 17 at idle is low, 30 would be better. Sounds like a well worn engine.
> You might try running a bit heavier oil if you don't want to tear it
> down. 20W 50 would probably do wonders.

17 at hot idle is PLENTY- a brand-new engine would give about 20 with a
standard oil pump and 10w30 oil. 30 at hot idle is ridiculous unless the
engine has a high-volume (non-stock) oil pump.