When an oil pressure sending unit goes bad is it possible to get erratic pressures? My oil pressure drops to zero when hot and at idle. I can rev the engine and the pressure comes up some. It's been like this for the last 2000 miles and the engine is still smooth with no knocks.

 

theres a good chance it the sending unit... swap it out for a new one (usually between 25 and 40 bucks) and if your oil pressure is still acting weird like that get back to us.

 

Sending unit is like $15 and is probably the problem. BUT it would be a good idea to test the oil pressure when you change the sender.....

 

You can either check it with a "mechanical" oil pressure gauge (some parts stores rent them) or you can just take a chance and replace the sending unit.

I buy the oil pressure sending units from Jeep. Way too many issues with some (not all) aftermarket oil pressure sending units. Well worth the extra money.

 

Anyone have a picture of where to find this sending unit on my engine? 2000 4.0 I6.

 

Directly above your oil filter.

 

I generally unplug mine when changing the oil so as to not snap it off when trying to get the oil filter off/on.

 

I hope your issue is the sending unit.

My 2000 cherokee did the same thing. low to NO oil pressure at idle when warm. The lack of oil pressure was a result of worn out crank and rod bearings. My head (a 0331 head) cracked, like soooo many 2000's did, and small amounts of coolant kept getting into the oil. Coolant=sand. Sand=bad bearings. $1000 later and I'm back in the good.
($1000 was for new head from Clearwater cylinder, oil pump, water pump, thermostat, various gaskets, and the new bearings. Oh, and I bought myself a new torque wrench )

 

Well naturally I just busted my OP sending unit removing the filter...Wish I would have read the earlier post before I did the work...Any ideas how to replace the thing, since it is broke off flush.