OIl pressure ?
Member
Joined: Mar 2010
Posts: 103
Likes: 1
From: Phoenix, AZ
Year: 96
Model: Cherokee
Engine: 2.5l I-4
Same here. I use Castrol GTX 10W-30. On a cold start, the needle will be above 40 psi, even at idle; it drops to below 40 psi when the engine is warmed up. It never exceeds 60 psi (the needle does), no matter, what, and at freeway speeds it settles a bit above halfway between 40 & 60 psi. It is not only normal that the needle goes up when you rev the engine above idle, but also a sign that the gauge isn't a total BS gadget (as is the case with so many others). Having said that, don't bet your life on this gauge being 100% accurate. Low oil pressure is usually caused by worn bearings (main/conn. rod), or by a faulty oil pump.
From what I know about other engines, oil pressure should be in the >15 psi range at idle, and rise about 10 psi with every 1,000 rpm. For reference, an oil filter's oil pressure relief bypass valve opens at around 30 psi, so that means, that above that the oil circulates unfiltered thru the engine.
From what I know about other engines, oil pressure should be in the >15 psi range at idle, and rise about 10 psi with every 1,000 rpm. For reference, an oil filter's oil pressure relief bypass valve opens at around 30 psi, so that means, that above that the oil circulates unfiltered thru the engine.
Last edited by SHO_91; Mar 12, 2010 at 11:42 PM.
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
Im pretty sure its normal. My '91 has done it since I bought it. Just a resting psi I'm guessing. Mine scares me sometimes though when its cold.. let it warm up for about 10 mins and it will still wanna try and idle at 60, but only til it runs down the road a bit. But anyway, Its normal. No worries.
Member
Joined: Mar 2010
Posts: 103
Likes: 1
From: Phoenix, AZ
Year: 96
Model: Cherokee
Engine: 2.5l I-4
If that ticking isn't outright knocking, I'd just stay with the factory recommendations (10W-30). If it comes from worn rod bearings, high-milage equivalents or 10W-40 may help it a little, although this needs to be taken care of before you spin a bearing or otherwise ruin your crank. Every engine ticks a little, most of the time it's the fuel injectors you hear on newer engines.
Junior Member
Joined: Aug 2010
Posts: 60
Likes: 0
From: Northern Utah
Year: 1992
Model: Cherokee
Engine: 4.0
Same here. I use Castrol GTX 10W-30. On a cold start, the needle will be above 40 psi, even at idle; it drops to below 40 psi when the engine is warmed up. It never exceeds 60 psi (the needle does), no matter, what, and at freeway speeds it settles a bit above halfway between 40 & 60 psi. It is not only normal that the needle goes up when you rev the engine above idle, but also a sign that the gauge isn't a total BS gadget (as is the case with so many others). Having said that, don't bet your life on this gauge being 100% accurate. Low oil pressure is usually caused by worn bearings (main/conn. rod), or by a faulty oil pump.
From what I know about other engines, oil pressure should be in the >15 psi range at idle, and rise about 10 psi with every 1,000 rpm. For reference, an oil filter's oil pressure relief bypass valve opens at around 30 psi, so that means, that above that the oil circulates unfiltered thru the engine.
From what I know about other engines, oil pressure should be in the >15 psi range at idle, and rise about 10 psi with every 1,000 rpm. For reference, an oil filter's oil pressure relief bypass valve opens at around 30 psi, so that means, that above that the oil circulates unfiltered thru the engine.
My '92 averages between 40 to 80 with 10W-40. Is that a bit high? That's normal driving speed as well (55-60mph) though maybe on the cold end of engine temp. Haven't gotten her up full bore on the interstate to check since changing Oil sensor. ha.
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