Oil pressure gauge going crazy?

[John]

I just did an oil change on my 1995 Jeep Cherokee and i have noticed that my oil pressure gauge has been all over the place whats going on here

 

[Lewis]

Could be the pump, or a kink in the hose, or a faulty gauge. Also when you first start up, it should be high because oil is thick after sitting for a while, so give it 10 minutes depending if it summer or winter. Also unstable idle and clogged oil passage ways, will do it too

 

[jasoncran]

Could be the pump, or a kink in the hose, or a faulty gauge. Also when you first start up, it should be high because oil is thick after sitting for a while, so give it 10 minutes depending if it summer or winter. Also unstable idle and clogged oil passage ways, will do it too

maybe in the process of the oil change he damaged the oil pressure sending unit, as its near the oil filter if john's car has an inline 6 cyl, john put a mechanic oil pressure guage and see, rule of thumb for every grand of tech there should be at least 10psi increasure of oil pressure, ie 1000 rpm oil pressure 10psi,

jason

 

[John]

I think i may have tightened the oil filter too much i wonder if that could be a problem.

 

[Lewis]

I think i may have tightened the oil filter too much i wonder if that could be a problem.

No

 

[jasoncran]

I think i may have tightened the oil filter too much i wonder if that could be a problem.

i agree with lewis and did you check your oil pressure with a oil pressure guage they sell at auto parts stores? What size engine do you have in your cherokee, john?
jason

 

[John]

4.0 liter

 

[jasoncran]

have u tried to see if the sending unit for oil gauge is damaged, if the 4.0 liter is the in line 6cyl engine then you may have damaged it, check by looking at the wire about the oil filter, it real easy to brake, i've done it a couple times, i doubt that an engines oil pressure would go whacky immediately after an oil change due to a pump problem.

jason

 

[PrimeRoot]

Sound Solution

John, not a good idea to run with abnormal pressure.

Dont discount your filter idea.

The way they are made has me amazed
at how few bad ones we see.

I could be wrong anymore,
but most automotive engine filters are "Full flow",
meaning all the oil must go thru it.
Seems to me theres a bypass valve inside many of them.
Maybe its plugged from the factory?

Im assuming there is a spring loaded spool
used to regulate the max pressure also,
but inside the engine or filter housing.
If the spring is broken, or if the spool is sticking...
there will be trouble.

Did you get the right jug of oil?
I had to stop using Castol in one of my vehicles way back.

Hey, most people never know when their oil pressure is bad.
The light never comes on til its too late.

My dad once said,
"Turn up the radio at the first sign of trouble."

 

[jasoncran]

Re: Sound Solution

John, not a good idea to run with abnormal pressure.

Dont discount your filter idea.

The way they are made has me amazed
at how few bad ones we see.

I could be wrong anymore,
but most automotive engine filters are "Full flow",
meaning all the oil must go thru it.
Seems to me theres a bypass valve inside many of them.
Maybe its plugged from the factory?

Im assuming there is a spring loaded spool
used to regulate the max pressure also,
but inside the engine or filter housing.
If the spring is broken, or if the spool is sticking...
there will be trouble.

Did you get the right jug of oil?
I had to stop using Castol in one of my vehicles way back.

Hey, most people never know when their oil pressure is bad.
The light never comes on til its too late.

My dad once said,
"Turn up the radio at the first sign of trouble."

oil filters have a pressure by pass in them, if they are made to automotive enginering standards, the pressure bleed of you spoke of is in the oil pump and that the case seals would blow, the oil pump is a positve feedback pressure,meaning that the oil pump has teeth that squeeze oil through the system and create a vaccum at the pump that helps suck the oil to the pump.

jason

 

[Lewis]

Also what weight oil are you using ?

 

[John]

10w-30.

 

[Lewis]

Where is the gauge mostly, in the high or the low range, after the car is hot ?

 

[John]

Low range.

 

[Lewis]

Take up to 10-40 that will increase the pressure if it does not, check that pump.

 

[John]

I'll giver her a try.

 

[stovebolts]

John,

Without being there to take a look, I'm leaning toward what Jason said. Let me see if I have this right first though ok?

Your Oil Pressure gauge was working fine until after you changed the oil. After your oil change, your oil pressure gauge starting acting wacky. What did you mean by wacky?

When I hear wacky, I immediately think that your gauge is swinging quickly and erratically without rhyme or reason. In my minds eye, I see a gauge that goes far to the right, then immediately drops to the left, staggers or 'sticks' for a moment and swings back to the right. Quick erratic jerks would indicate to me anyway that a wire to your sending unit is broke

Question.
At idle, where was your max oil pressure? I'm guessing that it used to run around 20psi?
At idle, what is your current max oil pressure reading? Is your gauge erratic at idle? What is it's max reading?

While driving, what was your max oil pressure? I'm guessing it used to run around 35-40psi?
What is your max oil pressure now?

 

[Lewis]

I am guessing also, because I am not there, but it could be a number of things.

 

[John]

The problem went away after i stuck some Lucas in there.

 

[Lewis]

The problem went away after i stuck some Lucas in there.

I love Lucas, use it in my oil and I also use Lucas tranny fluid.