I have a 97 Sahara with 178000 miles on it. I start it and the oil pressure reads about 40 psi but when I come to a stop the oil pressure goes down not to zero but pretty low and I was wondering if this is normal or should I be worried, I check the oil and it’s not low either so I don’t know what the problem is?
Oil pressure drops when stopped
- Thread starter 97 Sahara
- Start date
You have a "real" oil pressure gauge, which is supposed to vary with engine RPM. The engine revs higher, the oil pump spins faster, the oil pressure builds. As long as you have, according to the manual, 13 psi at hot idle, then you're fine. Another old school rule of thumb is 10 psi per 1000 rpm. The gauge also isn't super accurate, so if you're worried, buy a mechanical oil pressure gauge from Harbor Freight.
My Dad always said, "If you have ANY oil pressure when warm at idle, you are good."
i have the same vehicle as you with about 3k miles more. mine does the exact same thing, but when taking off from a stop will sometimes actually drop to 0 and the check gauges light will come on for a second then go out.
thrasher1tbl
New Member
Same year Sahara here, same issue. About 45 lbs on a cold start. After about 10-15 miles it starts to drop. On a hot start the check gauges comes on and then goes out as soon as the pressure builds up to anything. When I rev the engine it goes up. It averages about 13-22 lbs from idle to highway speeds. It has no engine noise at all. I’m just gonna let it rock.
Swapping out the oil pressure sensor for a new Mopar unit might bring some of your guys pressure readings back into spec. For the cost and ease of replacement, it's worth a shot. It is absolutely normal to start out with pressure around 60+ at cold start and get down to 15 at hot idle. That's how it came from the factory.
If it is indeed getting close to zero at hot idle and giving you a check gauges warning after you have verified that pressure is in fact correct, I would start with replacing the oil pump. If that doesn't fix it, you almost certainly have excessive bearing clearance i.e. your motor is worn out. At that point, the "proper fix" is a rebuild. Short of that though, you could probably get away with trying 10w-40 and/or a high volume pump to compensate for the excessive clearances a bit. In all likelihood that would work just fine for another 100000 miles.
And replacing an oil pump isn't near as scary as it sounds. But again, pressure dropping from 50+ to 15 at hot idle is completely normal. It's his every engine works---they just hide it on newer cars to prevent people who don't understand from worrying.
If it is indeed getting close to zero at hot idle and giving you a check gauges warning after you have verified that pressure is in fact correct, I would start with replacing the oil pump. If that doesn't fix it, you almost certainly have excessive bearing clearance i.e. your motor is worn out. At that point, the "proper fix" is a rebuild. Short of that though, you could probably get away with trying 10w-40 and/or a high volume pump to compensate for the excessive clearances a bit. In all likelihood that would work just fine for another 100000 miles.
And replacing an oil pump isn't near as scary as it sounds. But again, pressure dropping from 50+ to 15 at hot idle is completely normal. It's his every engine works---they just hide it on newer cars to prevent people who don't understand from worrying.