Oil Pressure on a 1999 TJ 4.0

[JeepinMaxx]

I've been happy that my 1999 TJ with just over 100K miles has had 80 PSI oil pressure at idle up to 3K RPM!  Today I turned the ignition switch on before firing the engine - Oil pressure was 80 PSI!  I assume the pressure switch is bad...

 

[kakirubi]

Ah.....yup..

 

[YJScrounge]

x2

 

[Greenhorn]

when ya put the new one in it'll say 10  lol

 

[RedJeepster1]

Definitely a pressure switch. Mine makes 60 cold and 25-30 at a hot idle. And I’ve only got like 40k on this bottom end.


Sent from my iPhone using Tapatalk Pro

 

[redjeep]

I get 40 to 50 cold and 20 hot

 

[Pete]

my 95 is 65-70 cold, 30ish hot at idle.  I replaced the sensor thinking it was bad but got the name numbers.

 

[bigdaddymack51]

Thats kind of a big spread from cold to hot.  Mine is not stock so I cant compare 70 cold - above 65 like 68ish hot.  In reference 72 ish to 65ish would be the thickness of the oil as it warms. I would think yours would have a little more fluctuation due to miles .  Was it like that always or as it aged. Stock gauges dont always read accurate  , they just read. Most stock sending units will read at 7 psi. Id like to see a mechanical gauge on some of your engines.  FjR68

 

[JeepinMaxx]

Finally replaced the sending unit for around $47!

Cold at idle

Hot at idle

At 2800 RPM

 

[JeepinMaxx]

 

[bigdaddymack51]

That look really normal .  Electric gauges arent that accurate anyway. Mechanical gauge has the tube going from the engine to the gauge. What you see is what the engine is getting . If you got a 100K on this motor , You should be happy and it shows youve taken care of it. FjR68

 

[XtraChrisP]

Agreed that it’s taken care of.... except that CEL....

 

[JeepinMaxx]

Agreed that it’s taken care of.... except that CEL....

  Yep - bad down stream O2 sensor...  not looking forward to working on that!

 

[TJlongworth]

set of torches and a good open end wrench...

 

[RedJeepster1]

Rev limiter works as a good substitute for the torch set  :rotflmao:

 

[A new level]

Rev limiter works as a good substitute for the torch set  :rotflmao:

Spoken like a true XJ guy! Lol

 

[kakirubi]

They make special sockets for that.  My preference is cut the wire, use some map gas, kroil and a 1/2 drive 6pt socket.

 

[bigdaddymack51]

Most of those slotted sockets will open up under torque. Choose wisely  FjR68