Hey guys,

I've got a 2000 XJ sport with 154,000 miles. I've been using Rotella t6 5w-40 for the past 2 oil changes now and its been running fine. Until this morning, on my way to class i noticed the CHECK GAUGES light come on on the cluster and i saw that my oil pressure was near zero. So I parked checked the oil level, everything was fine. Checked under valve cover cap, everything was fine. Got back in and kept driving, the issue remained. Whenever the engine is warm and im stopped and idling the oil pressure would drop and the light would come on.

So I went home, and did my oil change a little early, WIX and Rotella T6.
Did not fix the problem, so I went to autozone and picked up a pressure sending switch and replaced it. Did not fix the problem.

So now I'm at a standstill, I do not know how to proceed. Any help is appreciated, also is it safe to drive to class and back?

Incase youre wondering, the head gasket was changed in 2007.

Thanks

 

Are u able to verify with a mechanical gauge?

 

I am not, I do not have one .

 

Mine has been doing this for well over 20k with 292k on it. Have read its a common problem. Not sure where the problem resides and Im not so sure its a real problem. Have heard a dirty oil pickup. Im due for a motor so Im not digging deeper into it. Sorry not much help in a solution.

Edit: as long as pressure comes back up to normal under acceleration I think its ok.

 

You might consider something like this as insurance...

 

if i remove the pressure sender unit, can i just reinstall it? or do I need to put plumbers tape or something on it before i screw it back in?

I ask because im thinking it might be clogged and if i remove it and rev it to like 4k rpms might push some sludge out if its in there.

 

Senders and/or gauges are crap on these. Cheap aftermarket senders suck, and the port that the sender threads into gets dirty, which means that no matter how many times you replace it, it still won't read right.

Remove the sender again, clean out the port with pipe cleaner.

Even under perfect conditions, my buddy has seen 20psi difference between oem gauge and an actual mechanical gauge.

If you truly had zero oil pressure, you'd hear it.

 

when i remove and replace the sender, do I need to apply anything to the threads?

 

No. At least, not usually. They are pipe threads which usually seal pretty well. Install and check for leaks.

 

So I removed the sender unit and started the car. I will not elaborate as to what happened, i will however reassure you that I HAVE PLENTY OF OIL PRESSURE at the brass thingie... So there is no sludge build up (I figured since Im very timely with my oil changes and quality)... Any other suggestions? Could it be the pump? or pump screen? and if its just the screen, does the pump need to be replaced with it?


Thanks ._.

Also I will not just accept that this happens, my jeep has been running fine for years. This is a failure and must be corrected. Also I'm a bit OCD when it comes to my xj.

 

I haven't had a Jeep engine apart ( yet) but the oil pump has a regulator/by-pass valve, ( regulated to 75 PSI max.) that can get stuck partially open if something like debris gets stuck in it. Had it happen on GM pumps, which are gear pumps, same as the Jeep......
Only way to get to the pump is oil pan removal.

 

Why did you switch to a full synthetic with those miles? The oil you chose also has aggressive detergents not needed in a properly maintained gasoline motor.

 

We sometimes have a tendency to do too good on some things, like over-kill on oil, spark plugs (platinum etc) which an engine doesn't usually really need. High mileage engines can have a lot of varnish & sludge build up, which is best left alone......

Been there.....

Bill

 

So we'll just assume the sender passages aren't plugged and move on.

How low is the gauge dropping? Zero?
When the pressure drops low- do you hear any new engine noise?
I know it's been mentioned before, but screwing in a mechanical gauge at this point is really necessary to figure out whether you have a real pressure problem or a gauge problem. XJ's are good at both.
You can probably rent/borrow one from one of the parts houses.

Nothing wrong with your choice of oil, a lot of folks here run T6 with no ill effects. True that it has good detergents, but it isn't going to knock stuff off in chunks like some solvent based additives do. It's still relatively mild.

 

Most of your local parts stores "rent" kits of sorts. Typically you pay for it, and get your refund when you return it.
Either do this or find someone near you that will let you use a mechanical oil pressure gauge. This is the ONLY way to confirm your correct pressure. With your sender plugged in, if you have a scanner or other OBD apparatus that shows you info, you can see what that says in comparison to your dash gauge. Even then, that is only based on the sender reading.