silversport00

Every so often the oil gauge will drop to zero if my jeep cherokee is in idle, then once the gas is applied the oil pressure returns to the middle. Is this common? Possibly something wrong with the oil sending unit? My first vehicle so any suggestions are appreciated.

bigbadon

Seems to be a common problem. Mine does the same and I have verified with a mechanical gauge that the pressure is 3-5 psi at hot idle. That is not a real gauge on the later wj and it will drop to zero when actual pressure is below 8 psi. The chime is annoying but I just live with it....been that way for 15k.

kjc

Yes, the sending units often go bad, and from what i've read, they're not known for their accuracy in the first place. If it's leaking, they're cheap to replace. In an engine with any sludge, the channel in the block itself can block oil getting to the sender.
*Also, under 'any suggestions appreciated' It always helps to include your jeep model, year, engine etc. Some problems are known for specific models/years, but not as common on others.

silversport00

Oh okay thanks its a 2000 cherokee sport aka silversport00

bigbadon

Disregard my post. The 2000 has a real analog gauge and sender

Trev1006

Thats kinda low, as a minimum rule I run 10 psi for every 1,000 rmp. How many miles on your engine? Mine New engine with low miles holds about 22 psi at idle and it jumps above 40 immediately when I bump the gas. Any lifter tic an high rpms? Burn oil? Leaky rear main? Oil pan or oil filter adapter?

1991Jeep_Man

Replace sending unit. They break sometimes with oil changes. There's a hundred other threads about this SAME issue.

Trev1006

I run good aftermarket gauges so I can rely on the reading I'm gettin too.

Mctowelie

Not to hijack this thread but, I have around 40-45 psi at any rpm
, and at idle its at 25 sometimes 35psi. Its a '97 xj @ 169k and has a lifter tick noticable only when at idle, and was curious as to how the lifter tick contributes?

kjc

The 4.0 lifter tick is a safety feature. They're engineered to be noisy at idle so after a couple six packs you don't accidently try to start the engine while it's already running.

Trev1006

Your lifter probably has a slow leak and bleeds down at idle. But once you rev it up, the oil pump flows more pressure and volume, pumping your lifter back up. A ticking lifter it on its way to becoming a collapsed lifter. Some tic for years and never collapse tho. If it sits for a few days it probably ticks bad when you first start it right?