Having oil leak on Grand Cherokee 1999

40 psi is perfect. I love than engine, some call it the iron duke. You need to find the leak. Clean the engine very well. It's most likely a valve cover seal or crank seal if you see it on the engine from the engine compartment. It could be the oil pan gasket too. You should be able to find it. It will usually stop leaking once you turn the motor off and stop sloshing it around. Let me know what you find out. If that's too much of a hastle for you, some shops like pep boys offer a leak diagnosis where they put dye in your oil, but they'll just probably tell you that everything is leaking. See what you can find out yourself. Park it over cardboard, to find out where it's landing exactly and then follow it back up to the source.

PURPLE POWER WORKS GREAT FOR DE-GREASING AN ENGINE

BE CAREFUL NOT TO GET IT ON YOUR EXTERIOR PAINT

I TRY TO DO IT IN A WIND-FREE PLACE, AND I RINSE MY PAINT ANYWAY, WHILE I LET IT THE "PP" EATS ON THE GREASE FOR 5-10 MINUTESTHEN I RINSE IT WITH A HARD STEAM FROM THE GARDEN HOSE, LASTLY, I RINSE MY BODY AGAIN, IN CASE I SPLATTERED IT. IT REALLY DON'T HURT YOU PAINT, IF YOU RINSE IT OFF PRETTY QUICK. I HAVE LAID WET TOWELS OVER BODY PARTS TOO.

AS FAR AS OIL PRESSURE---MANY TIMES AN ELECTRIC GAUGE CAN BE INACCURATE---THE BEST AND MOST ACCURATE IS A MECHANICAL GAUGE

YOU CAN REMOVE THE OIL SENDER AND INSTALL A TEMPORARY MECHANICAL GAUGE, A LONG TUBE WILL LET YOU BRING IT FROM UNDER THE HOOD, AND ON THE DASH OR THE SEAT BESIDE YOU. YOU CAN THEN MONITOR WHAT EXACTLY IS HAPPENING AS YOU DRIVE.

IMMA PLUMBER, I HAVE A BOILER TYPE GAUGE ADAPTED TO A PLASTIC TUBE WITH A FITTING FOR THE ENGINE END. AUTO PARTS STORES HAVE THE SAME SORTA SYSTEM WITH A "PERTTY" GAUGE THAT YOU CAN MOUNT UNDER THE DASH---YOU DON'T HAVE TO MOUNT IT, JUST USE IT TEMPORARY (GET ONE YOU LIKE, JUST IN CASE YOU DO WANT TO MOUNT IT!). SEE MY PIC BELOW

THESE KITS COME WITH EITHER A COPPER TUBE, OR A PLASTIC TUBE---I RECOMMEND THE PLASTIC FOR A TEMPORARY USE. VIBRATIONS AND ENGINE TORQUE TEND TO BREAK THE COPPER.

ONCE YOU SEE TRUE OIL PRESSURE, MOST OF THE TIME IT IS A SENDER PROBLEM--SOMETIMES IT'S THE GAUGE IN YOUR DASH

AND SOMETIMES EVERYTHING IS THE SAME W/ THE MECHANICAL, AS WITH THE ELECTRIC. IN THIS CASE, THE ENGINE IS WORN, OR SOMETHING IN THE ENGINE MAKES IT FLUCTUATE.

WITH MY 1977 CJ 5, YEARS AGO (BEFORE I FINALLY REBUILT THE ENGINE), MY PRESSURE HAD DWINDLED SOME OVER THE YEARS TO ABOUT 20 PSI, A "HIGH VOLUME" OIL PUMP WAS THE CURE FOR MANY YEARS. I WAS TOLD BY A LOCAL PRODUCTION ENGINE MACHINE SHOP OWNER (A FRIEND) THAT "4 PSI" WILL SUFFICIENTLY LUBRICATE AN ENGINE.

PERSONALLY I WOULD NOT PREFER LESS THAN 20. AFTER BREAKING AN ENGINE IN ABOUT 3 OIL CHANGES (9000 MILES FOR ME) I SUBSTITUTE A QUART OF LUCAS OIL STABILIZER FOR ONE OF MY NORMAL 5 QUARTS OF OIL. COSTS ME ABOUT AN EXTRA $7 OR SO EACH AND EVERY CHANGE.

THIS 258 6 CYL NOW HAS ABOUT 210,000 MILES ON IT. EVERY OTHER JEEP/ ENGINE LASTED A LITTLE OVER 100,000 MILES BEFORE THEY NEED TO BE REBUILT. IT DOES NOT BURN OIL--COLD OIL PRESSURE STARTS AT ABOUT 60 PSI--HOT IT DROPS TO 50 PSI, MY VACUUM AT IDLE IS A STEADY 21 Hg. I THINK IT'S WORTH THE EXTRA $7!

THIS COUPLED WITH A 4 BBL INTAKE AND A HOLLEY 390 CFM CARB (PROPERLY JETTED AND ADJUSTED) MY MPG HAS GONE FROM 15 MPG (ORIGINAL CARTER BBD CARB) TO 18 MPG WITH THE HOLLEY. I INSTALLED ED MAINLY FOR THE MPGs--BUT IT ALSO PROVIDES MEGA POWER AND PICK-UP IF I PUT MY FOOT IN IT! THIS JEEP (MR. JEEP) IS MY DAILY DRIVER, I WOULDN'T TRADE IT FOR THE WORLD! "WILLY" MY '46 WILLYS JUST AIN'T GEARED FOR MPG WITH A 1/5.38 GEAR RATIO. COULDN'T GET RID OF HIM EITHER!

IS THIS YOU?

http://www.autozone.com/autozone/parts/Duralast-Oil-Pressure-Switch/1999-Jeep-Cherokee-4WD/_/N-jdmfiZ8znc6?itemIdentifier=704844_0_8450_

I PUNCHED IN A 4.0L ENGINE TO GET THIS

YOUR TURN

THE MEDIC

I JUST CHECKED

YOUR SEAL IS A 2 PIECE (SIMILAR TO MY CJ)

http://www.autozone.com/autozone/parts/Felpro-Rear-Main-Seals/1999-Jeep-Cherokee-4WD/_/N-jdmfiZ8znna?itemIdentifier=73831_124273_0_19125

THE ENGINE DOES *NOT* HAVE TO BE PULLED OUT AND SEPARATED FROM THE TRANNY TO INSTALL THIS

JUST REMOVE THE PAN AND REAR MAIN CAP (ON MY CJ I HAVE TO TAKE THE ENGINE MOUNTS LOOSE AND LIFT THE ENGINE 2 INCHES TO "WIGGLE" THE PAN OUT.

LET ME KNOW HOW MUCH THE REAR MAIN IS GONNA SET YOU BACK...MAY HAVE OTHER AVENUES, IF THE COST SORTA DOUBLES YOU OVER.....I COULD DO MY CJ REAR MAIN IN LESS THAN 3 HRs IF WORK ACCURATELY, AND WAS UNINTERRUPTED.....AND I DON'T DO THIS STUFF ALL OF THE TIME, IMMA PLUMBER!

I UNDERSTAND MAKING A LIVING AND PAYING THE BILLS, BUT I ALSO UNDERSTAND BEING TAKEN ADVANTAGE OF TOO

YOUR TURN

THE MEDIC

YOU SAW THE PRICE FOR THE SEAL IN MY LINK---WHAT DID THE STEALERSHIP GET FOR IT?

I JUST WENT BACK UP TOP, YOU ARE CLICKING ON MY LINKS?

I'M A DIYer FROM WAY BACK---I FIND THAT AFTERMARKET PARTS WORK JUST AS WELL AS THE OEM, SO DON'T LET SOMEONE LEAD YOU INTO THINKING THAT YOU "HAVE TO" SPEND THE BIG BUCKS TO DO IT RIGHT!

IF YOU WERE TO PURCHASE THE OIL SENDER--THE REAR MAIN SEAL--OIL PAN GASKET, YOURSELF. THE FELLER THAT HAS BEEN WORKING DOWN AT THE SMALL MA AND POP, SELF SERVICE SALVAGE YARD FOR QUITE SOME TIME. MIGHT INSTALL THESE 3 ITEMS, GUESSING.$200 OR LESS

NOW KEEP IN MIND, YOU MUST DETERMINE THE ABILITIES OF THESE FOLKS BY LOOKING AT THEIR WORK. AROUND HERE, I COULD EZily HOOK YOU UP WITH MAYBE 5 OR 6 OF THESE GUYS. THEY ARE EVERYWHERE, AND GIVEN LITTLE CREDIT. YOUR REPAIRS HAVE NOTHING TO DO WITH COMPUTER COMPONENTS. THEY ARE BASIC REPAIRS THAT A JEEP MECHANIC FROM 1946 COULD PERFORM. I KNOW THIS BECAUSE I HAVE DONE THE WHOLE KIT AND KABOOTLE TO MY '46

I GUESS WHAT I'M SAYING IS. YOUR REPAIRS DO NOT REQUIRE 10 CONSULTATIONS WITH ROCKET SCIENCE ENGINEERS AND GOLD PLATED PARTS ARE UNNECESSARY---MR. PYLE FROM MAYBERRY COULD BE A WAY TO SAVE MONEY, MAKE A NEW FRIEND (HE WAS NOT ASE CERTIFIED EITHER)

DO WHAT YOU WANT--I JUST TRY TO OFFER SUGGESTIONS OR OPTIONS. I'VE BEEN AT THE MERCY OF OTHERS MYSELF.

KEEP US INFORMED ON HOW IT'S GOING

THE MEDIC

Everything seems good. Pressure would drop slightly when at idle and increase when engine rpm goes up.
Normal operating pressure is between 37 - 75 psi.

Minimum pressure is 13 psi at 600 rpm and can go up to 75 psi, which is the relief pressure.