Low oil pressure, help!

I have an 89 XJ with 204k+ miles, and after changing the oil + Seafoam in it with Castrol GTX 10w40 straight up, my oil pressure won't pump up. It was normal for a while, and the oil level is fine, but now even at highway speeds my oil pressure stays around 20-30 psi at the most. Did I clean out all that shit that was in there keeping my pressure up?


My jeep is also wanting to overheat a lot, despite the radiator flush, and new fan shroud I have, and I think that in turn with the pressure is making my sticky lifter problem worse. So to solve that problem I put a can of RESTORE into my oil because I read around on Jeepforum that it usually helps.

Also, when Idling at a stop light or just in the backyard, I notice that once in a great while my pressure will drop down to zero and it'll come right back up with a little bit of gas. What the hell is wrong??

I'm here in NC, where it's about 89 on a cool day this summer, so should I move to a heavier weight? Is my oil pump fubar?

Thanks!

Well, Your engine is getting old not just the oil pump. What was the oil pressure before the engine flush?
You could pull and clean the oil relief value. Inspect the seat (in block) for anything that would keep the plug from seating or cuts in seat. But that a long shot IM my book.
Also you may have plug the pickup with slug but the fresh oil should have cleared that up. luck
That oil presser for an engine with that many miles on it is about right. It's that quick drop that I would be concern about. most likely your just looking at running 20-50 or an HD 40. I run HD 40 in the summer when towing.

While the oil is still hot drain it into a CLEAN container, look for chunks or better yet run it thru a strainer as it comes out. If you cleaned the sludge out it may be sitting in the pan and when the engine pulls oil it gets pulled up into the screen. You may end up doing that a couple of times if stuff keeps coming out. the other thing is that if it plugs the filter the bypass kicks in and bypasses the filter. BTW, what brand filter are you using ? If it's a fram try something else, purolator, Mopar, wix, hastings anything but fram..
I said clean container as you can reuse it, maybe, but after all that stuff you put in there I don't know if I would.

Well I put a Purolator filter in there just about an hour ago. I'm going to wait until tomorrow after work to see if the pressure will be higher while cold. I really don't want to touch the thing anymore. I've replaced the water pump, several coolant bottles/caps in the past, and the radiator is about 80k old, freshly flushed twice, and the coolant is nice and green (50/50 mix) all the way through. Stupid closed system, I don't know what else it could be short of the fan clutch, but I don't think there's anything wrong with that, it has a bit of resistance when the engine is hot, so that means its good right?

The thermostat is good, I think, I can watch the temp gauge go up to around 220, then drop down to 180 when it opens, so that shows that it's working, unless it's not working enough.

After I get paid tomorrow I'll grab a cheap oil pressure gauge, I really don't feel like taking any more money out of my "Jeep lift monies " accoun...er envelope.

many years ago when i switched over to synthetic oil it knocked enough crud loose to partially plug up the sending unit and my oil pressure dropped quite a bit, until i changed the unit, could be what happened to yours? cheap and easy to change.

I'll try a new sending unit. $6 is better than $20 for a new one + gauge. Any ideas on the overheating? During my drive home, which is about 25 miles, the jeep is fine through town, but at around 6 miles from my house, 19 miles into the trip, there's a big stretch of 55 mph, and then a big hill, and then a stoplight. It's usually right here that my temps start going up. Before this it's city driving for a few miles at 45mph, then a bunch of rural driving at 45-50 mph. You think the strain of the highish speed + the big hillclimb is enough to make my jeep say "aww screw it!" and start overheating? So if it's overheating at speed, then would it be my radiator?

Ryley --

You haven't mentioned what weight oil you are using, or if it's conventional or synthetic.

Yeah I did, i said it in the first post, Castrol GTX 10w40, conventional. I'm not sure if it's the high mileage or not, just remember that it's in the big white jug.

I'm running Valvoline 10w30 in my 2.5L w/ 125,000 and it runs at a steady 23 pounds of pressure. My temp stays at a consistent 190 or so.

I've had similar probs with my '89 4.0. Rebuilt the bottom end - polished the crankshaft, main and rod bearings, new high pressure pump, new radiator, oil cooler.

Still not great pressure.

Biggest improvement I got was when I switched to Mobil 1 15W-50. It's good stuff.

RyleyF said:

I'll try a new sending unit. $6 is better than $20 for a new one + gauge. Any ideas on the overheating? During my drive home, which is about 25 miles, the jeep is fine through town, but at around 6 miles from my house, 19 miles into the trip, there's a big stretch of 55 mph, and then a big hill, and then a stoplight. It's usually right here that my temps start going up. Before this it's city driving for a few miles at 45mph, then a bunch of rural driving at 45-50 mph. You think the strain of the highish speed + the big hillclimb is enough to make my jeep say "aww screw it!" and start overheating? So if it's overheating at speed, then would it be my radiator?

Click to expand...

Overheating? Boiling over? What's the temp?

Whoaaa, this thread is 4 months old! I still have the low pressure, I'm just learning to deal with it.

13 psi is satisfactory if the motor is hot.