JeepFNG

I decided to change the oil and Tanny fluid rather than the much dreaded heater core.everything seemd to go just fine. I had the engine running to check the tranny fluid level and noticed it knocking pretty bad I went to shut it off and noticed Zero Oil pressure.WTF? Oil level was fine the filter i replace was a fram PH 18 according to the book and the guy behind the counter at Advance this was the correct filter. Anyone have any Ideas on this one?

tjwalker

If you hear engine noise with low oil pressure, something is up! Filled back up with 6 quarts of oil?

Gotta look at work performed. You might want to swap out that Fram filter with a different one (I'm not a big fan of the basic Fram filter BTW) in the event that you have a faulty filter that is restricting flow.

Check the oil pressure sending unit, located directly above the oil filter. It is not unusual to hit that connector and dislodge it from the sending unit while you are swapping out your oil filter. But if that was the case, it may show zero oil pressure on the dash gauge, but you would NOT have the engine noise as it is not a true oil pressure issue.

Keep us updated.........

JeepFNG

Yep 6 quarts of oil, filter, no leaks This XJ is killin me it seems to be one thing after another. Burned a tax return trying to get it up to speed.Get one thing fixed something else pops up. Deer impact 3 days after i bought it did'nt help.. a buddy seems to think the oil Pump might not be primed.

rex21

I agree with tjwalker, get rid of the fram filter.

Also, did you change oil brands? When I did my first oil change after buying mine, I switched to high mileage oil, and mine showed zero oil pressure too. Took the oil pressure sending unit off and cleaned it, then re installed and it was back to normal. I think the new oil knocked some crap loose that blocked the sender.

Pelican

I don't mean to insult, but are you certain that you put the correct fluid in the correct fill tube/hole and checked the correct dip stick? This happens more often than you might think and I may as well go ahead and ask.

A damaged oil pressure sender might explain the zero oil pressure reading but not the knocking. Same with the filter. Wix/Napa, for one, are a good replacement for the Fram and you want to go ahead and do that now rather than wait until your next oil change.

salad

Knocking is definitely bad! If you didn't forget to put the drain plug back, the next thing I'd check is if your filter collapsed. A collapsed media can block flow, starving your engine of lubrication. Basic FRAMs are known for failure. Spin on a WIX or NAPA Gold and ser what happens. I eould not recommend running that engine until you get this resolved.

JeepFNG

Turns out I had smacked the Oil pressure sensor with the Oil Filter wrench and cracked the sensor. I swear someone put it on with a impact gun. I went to take it off and it fell apart in my hands. New sensor problem solved!

JeepFNG

I'm a Tard sometimes no dought. But not that much of a tard!

Pelican

I'm not sure why the busted sender caused knocking but glad you solved it!

You have my permission to make an equally demeaning comment the next time I come up with some inanity -- which will almost certainly happen, probably sooner than later.

cruiser54

Correct. That does not explain the knocking.

JeepFNG

I knocks somtimes because it Idles like crap yet another problem i need to solve

cruiser54

So the knock was not related to the recent oil change?

JeepFNG

That is correct Cruiser, Im looking for your post on cleaning the IAC to try and get that solved

Big David

I had a TJ with the 4.0.We were riding thru the mnt's & out of nowhere the oil pressure went to 0 & the "dash alarm" sounded.

I thought my oil pump went out.My wife says "change the oil filter".It was a Fram.Got a new filter & fixed the problem.

I always used Fram untill I got on here.I was ignorant on the matter.I still miss the black "grippy" part of the filter.

I started using Wix (the NAPA store brand) & found it's actually priced cheaper than the Fram filters.

MAKE THE SWITCH-NOW.

Your engine will thank you.

cruiser54

They're all in the "pink link" in my signature, but here it is especially for you.



Courtesy of TJWalker:

--------------------------------------------------------------------
The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

"Gently" wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled