The very first thing to do is to fire the first shop you took the jeep to. They didn't install a mechanical pressure gauge to verify the oil pressure was low, and just threw a part on there hoping to fix it.

So...you'll have to decide if you want to tackle this yourself or not. You will need to install a mechanical gauge in place of the pressure sender to verify exactly what oil pressure you have. According to the FSM, on a hot engine, at idle, the minimum oil pressure you should have is 13 psi. At 1600 rpm, it should be 37 to 75 psi. If you have less than this, you then will need to have the oil pump inspected. It could be that the pickup tube is cracked, the pump itself is worn or even the bypass is stuck open or its spring broken. My guess is that this is where you will find your problem. A better shop will also check the crankshaft bearings and connecting rod bearing tolerances while the pan is off to inspect / replace the pump, particularly if the oil pressure is indeed low.

Regarding your loss of coolant, you will need to have a shop pressure test the cooling system to see where the coolant is leaking out at. It could be a cracked head open to the exhaust side of the engine. Do you notice any steam or condensation dripping out of the tailpipe? The other possibility is that its leaking at the heater core, but you can usually smell antifreeze inside the cab if that's the case. You don't by any chance notice any greasy film on the inside of your windshield? If you have an automatic transmission, the radiator could be leaking internally into the transmission oil. Once again, have a shop test it for you.

The things I've described above are able to be done by a good mechanic that has the right tools. I'm not trying to discourage you from doing this yourself, but you may have a lot less heartburn if you let a good shop handle these two problems for you.

Good luck

 

this guy just had a similar problem

http://www.jeepforum.com/forum/showthread.php?t=595475

 

If you're loosing coolant I don't think it's a oil pressure sender. I had the exact same issue on my 01 and had to replace the engine since the head was cracked and the main bearing spun out. I hope that's not your case tho.

 

I have a 2000 TJ with the same type of issue. Once the engine warms up and i stop accelerating or shift to neutral the oil pressure drops to zero and only returns to normal once the RPM's have returned to around 2000. I also had a mysterious coolant leak ( was loosing coolant but no visible leak) which turned out to be a blown head gasket. I replaced the gasket but believe i might have a cracked head an not necessarily a gasket issue. Am i better off replacing the motor?

 

I just noticed all of these symptoms on my jeep tonight and did a search for blown head gaskets and this came up. I looked under my jeep and oil was leaking at lots of random places i.e) oil filter, oil pan, block and was thrown onto the exaust pipes. I just changed the oil so i checked to make sure my filter was tight and it was. My gauge is also dropping to zero at idle and around 2,000 rpm it jumps up again.
A while ago, I was having some cooling issues so I replaced the water pump, thermostat and flushed the radiator but now the heat is coming back. Im reading around 230-240 on the gauge. while I checked out my oil leaks every where, I went to close the hood and noticed a huge build-up of coolant on the inside of my hood and started finding more coolant around the oil pan around the overflow bottle and leaking down my track bar and the dif. Looked like there was an explosion of coolant in there:brickwall. I'm beginning to think this is a blown gasket or cracked block but the jeep is still running good. I hope its neither of those and turns out to be a bad hose or something. Not trying to Hijack but I need some help too with this. I've got the same symtoms!

 

sounds like a blown head gasket or cracked head/block. sorry!!

 

took it to a trusted mechanic and had some pressure tests ran. The pressure test was fine and im not leaking any collant anywhere, but my fan clutch went out which was causing me to overheat. I aslo have a small valve leak which the mechanic recommended switching to high mileage oil next oil change.

 

Don't switch to high mileage oil. That statement alone would make me not trust this person. High mileage oil does nothing but cover up problems that need to be fixed.

 

I had

I had the same issue with my old engine at 137,000 miles, i put a mechanical gauge on it and it was in fact dropping out on oil psi at a idle after heating up to operating temp, but no noise or lifter noise at all which surprised me, you would think it would have made at the least a little racket
I installed a high volume oil pump and it had 40 psi idle and 50-55 at higher rpm

 

2000 Jeep Wrangler 4.0L 62,000mi.

Ive had the same problems, any definitive answers?

No oil/coolant leaks anywhere. No funky looking oil or coolant or black/blue smoke out of tail pipe. Losing oil and coolant slowly and no oil pressure after its at running temp. So this is the jist of things:

Oil pressure is fine cold but after it warms (oil thins) up my oil pressure drops down to 0. When accelerating it goes back up. We put a pressure gauge on where the sending unit goes and it reads zero at idle. So it is not the sending unit.
Next step oil pump, but if its fine when its cold it doesnt seem to me that it would be the pump. I dont want to throw money away by changing unrelated parts.
My mechanic tells me its the camshaft seals. Doesnt seem right on an engine with such low miles, especially the "bullet proof" inline 6. Im at a loss. He estimated changing the seals for $800, but he also said to add a higher viscosity oil and it would be fine if I left it the way it is?? I dont see any kind of engine making it to 100,000mi. with this problems. Anyone else find a solution to this apparent common problem???

 

i had this problem last week. went to autozone bought a oil pressure sending unit for 25 bucks and no more problems for me..

 

Just an update. I ended up replacing the engine with a crate engine. I could of had it rebuilt but there was no telling what damage was done. Figured do it once and do it right. Runs great. Here's a few pics from last weekend. :cheers2: