The oil pressure gauge on my TJ is high, 40+, while the engine runs at
road speeds, but at idle the needle sometimes drops to zero, and then
climbs up to about 10 pounds. Sometimes while at idle it swings back
and forth between 0 and 10.

I disconnected the electric oil pressure sending unit and attached a
mechanical gauge... same behavior... the pressure falls and rises at
idle like before.

The Jeep is a 1997 TJ 4 cylinder, with 71,000 miles.

Apparently I need a new oil pump. But I wonder if the oil pump might be
good and something else is causing the deviance.

Is the pump driven by the distributer shaft?... could the pump be good
and something else is causing the oil pressure to sometimes drop and
rise like that?

The Jeep runs well and behaves normally at idle or road speeds.

I change oil and filter every 3,000 miles.

TIA for your advice.

Ralph
RalphDL@webtv.net

God exists, or God does not exist, or I am God and I am dreaming all
this.

 

I would check the connections starting at the sending unit.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Ralph DL wrote:
>
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.
>
> The Jeep is a 1997 TJ 4 cylinder, with 71,000 miles.
>
> Apparently I need a new oil pump. But I wonder if the oil pump might be
> good and something else is causing the deviance.
>
> Is the pump driven by the distributer shaft?... could the pump be good
> and something else is causing the oil pressure to sometimes drop and
> rise like that?
>
> The Jeep runs well and behaves normally at idle or road speeds.
>
> I change oil and filter every 3,000 miles.
>
> TIA for your advice.
>
> Ralph
> RalphDL@webtv.net
>
> God exists, or God does not exist, or I am God and I am dreaming all
> this.

 

I would check the connections starting at the sending unit.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Ralph DL wrote:
>
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.
>
> The Jeep is a 1997 TJ 4 cylinder, with 71,000 miles.
>
> Apparently I need a new oil pump. But I wonder if the oil pump might be
> good and something else is causing the deviance.
>
> Is the pump driven by the distributer shaft?... could the pump be good
> and something else is causing the oil pressure to sometimes drop and
> rise like that?
>
> The Jeep runs well and behaves normally at idle or road speeds.
>
> I change oil and filter every 3,000 miles.
>
> TIA for your advice.
>
> Ralph
> RalphDL@webtv.net
>
> God exists, or God does not exist, or I am God and I am dreaming all
> this.

 

I would check the connections starting at the sending unit.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Ralph DL wrote:
>
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.
>
> The Jeep is a 1997 TJ 4 cylinder, with 71,000 miles.
>
> Apparently I need a new oil pump. But I wonder if the oil pump might be
> good and something else is causing the deviance.
>
> Is the pump driven by the distributer shaft?... could the pump be good
> and something else is causing the oil pressure to sometimes drop and
> rise like that?
>
> The Jeep runs well and behaves normally at idle or road speeds.
>
> I change oil and filter every 3,000 miles.
>
> TIA for your advice.
>
> Ralph
> RalphDL@webtv.net
>
> God exists, or God does not exist, or I am God and I am dreaming all
> this.

 

I would check the connections starting at the sending unit.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Ralph DL wrote:
>
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.
>
> The Jeep is a 1997 TJ 4 cylinder, with 71,000 miles.
>
> Apparently I need a new oil pump. But I wonder if the oil pump might be
> good and something else is causing the deviance.
>
> Is the pump driven by the distributer shaft?... could the pump be good
> and something else is causing the oil pressure to sometimes drop and
> rise like that?
>
> The Jeep runs well and behaves normally at idle or road speeds.
>
> I change oil and filter every 3,000 miles.
>
> TIA for your advice.
>
> Ralph
> RalphDL@webtv.net
>
> God exists, or God does not exist, or I am God and I am dreaming all
> this.

 

Ralph DL wrote:
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.

Sounds pretty cut and dried, if it's not the Oil pump then you've got
something very strange going on like a cam bearing with a crack that's
letting oil pulse out or something like that...

On the other hand if it is the pump and you aren't hearing lifter noise
yet then it's probably not too late for your bearings... lifters deflate
and start clattering below about 9 or 10 PSI.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

 

Ralph DL wrote:
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.

Sounds pretty cut and dried, if it's not the Oil pump then you've got
something very strange going on like a cam bearing with a crack that's
letting oil pulse out or something like that...

On the other hand if it is the pump and you aren't hearing lifter noise
yet then it's probably not too late for your bearings... lifters deflate
and start clattering below about 9 or 10 PSI.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

 

Ralph DL wrote:
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.

Sounds pretty cut and dried, if it's not the Oil pump then you've got
something very strange going on like a cam bearing with a crack that's
letting oil pulse out or something like that...

On the other hand if it is the pump and you aren't hearing lifter noise
yet then it's probably not too late for your bearings... lifters deflate
and start clattering below about 9 or 10 PSI.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

 

Ralph DL wrote:
> The oil pressure gauge on my TJ is high, 40+, while the engine runs at
> road speeds, but at idle the needle sometimes drops to zero, and then
> climbs up to about 10 pounds. Sometimes while at idle it swings back
> and forth between 0 and 10.
>
> I disconnected the electric oil pressure sending unit and attached a
> mechanical gauge... same behavior... the pressure falls and rises at
> idle like before.

Sounds pretty cut and dried, if it's not the Oil pump then you've got
something very strange going on like a cam bearing with a crack that's
letting oil pulse out or something like that...

On the other hand if it is the pump and you aren't hearing lifter noise
yet then it's probably not too late for your bearings... lifters deflate
and start clattering below about 9 or 10 PSI.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

 

Bill ------

Please re-read my post... the oil pressure varies even when I replace
the electrical measurement of oil pressure with a mechanical oil
pressure gauge.

The mechanical oil pressure gauge is attached to a tube which screws
into the block... oil actually goes from the engine up the tube and
applies direct pressre to a diaphragm/spring coil loaded needle... this
is the most accurate albeit old-fashion way of measurine engine oil
pressure.

That's why I asked if it could be more than an oil pump problem.

Ralph

God exists, or God does not exist, or I am God and I am dreaming all
this.