I have a 2000 Grand Cherokee Limited 4.7L that I have been pouring money into because I love this vehicle. The latest thing to happen occurred after I changed the oil. The next time I started it the gauge would go down to 0 as it idled. It never did that before. Would synthetic oil do this. I am changing the oil pressure sending unit today to see if that helps. If it winds up being the oil filter is that hard to get to? Thanks for any help I can get.

 

oil filter? do you mean oil pump????? have you used a mechanical gauge to check the pressure?

 

Synthetic often does drop oil pressure a little but not a concern. Synthetic flows easier with less restriction and FLOW is the dynamics of lubrication. Pressure represents deadhead against flow.

 

yes I meant oil pump.

 

for the oil pump you have to pull the oil pan. it can be pretty tricky to get the oil pan out from under the jeep. once its out two bolts for the oil pump.

 

The oil pump on a 4.7 is driven off of the front of the crankshaft. You have to pull the timing cover. Pumps don't make pressure, they only make the oil flow. What brand oil filter did you install?

 

did you verify the pressure is actually low by using a mechanical gauge?

 

Changed the oil pressure sending unit and seems to have fixed the problem. Thanks to all.