Oil pressure fluctuating
01-19-2014, 07:55 AM
#17
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Year: 1999
Model: Cherokee
Engine: 4.0
IMHO your going way to many miles between oil changes with that many miles on your XJ. 3 mo. or 3,000 mi. max. Then use a high quality oil filter like NAPA Gold ( for a store brand made by WIX ) or a WIX filter are all I have used for over 30 years since I started cutting open filters. Some are so poor you would be amazed if you cut them open like Fram for one. At every oil change to check for early engine wear in race car engines then all my cars.
Oil quality is important also as are the additives they use in my XJ I run Castrol Oil 10w-30 everything else gets Castrol Syntec. Except for my Diesel Pusher Motorhome Rotella T for it all 4 gal.
Oil quality is important also as are the additives they use in my XJ I run Castrol Oil 10w-30 everything else gets Castrol Syntec. Except for my Diesel Pusher Motorhome Rotella T for it all 4 gal.
01-19-2014, 08:05 AM
#18
Herp Derp Jerp
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Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Let's not turn this into an oil thread... Suffice to say with an engine oil made in the last decade there's no reason to change oil at 3k miles anymore unless your engine has a problem.
Mister OP as others have mentioned, a bad OPSU and a clogged galley leading to it can read poorly. You'll want to get that sensor out and clean the little passage with a pipe cleaner. If you break the sensor you can get a new one, otherwise if it looks okay just sit on it for now. I'd confirm that its readig is accurate (or not) with a mechancal testing gauge before replacing anything.
As well you need to drain your oil and check for pollution from gas and coolant. It would be wise to pull the spark plugs and give them a boo, if you're burning oil it should be evident. Mind you you may be leaking it all over the bottom of your Jeep... You'll find out once you get down there!
As for the coolant color, I'm going to guess you haven't done a flush since you bought it?
Mister OP as others have mentioned, a bad OPSU and a clogged galley leading to it can read poorly. You'll want to get that sensor out and clean the little passage with a pipe cleaner. If you break the sensor you can get a new one, otherwise if it looks okay just sit on it for now. I'd confirm that its readig is accurate (or not) with a mechancal testing gauge before replacing anything.
As well you need to drain your oil and check for pollution from gas and coolant. It would be wise to pull the spark plugs and give them a boo, if you're burning oil it should be evident. Mind you you may be leaking it all over the bottom of your Jeep... You'll find out once you get down there!
As for the coolant color, I'm going to guess you haven't done a flush since you bought it?
01-19-2014, 09:03 AM
#19
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Year: 1999
Model: Cherokee
Engine: 4.0
I have a 98 XJ 4.0 with 213k miles
In the previous 1-2 years have always noticed that when I get to a stop light, the oil pressure sometimes dropped from the normal 40 psi. It usually never went below 25.
Lately this phenomenon started being more importand and happening more often, I noticed that in several cases the oil pressure drops to low values, around 10 psi. The check gauges light never came on, so far.
It is very difficult to identify a rule of thumb for this to happen, but I would say that this mostly happens when the engine is at low rpms and it is getting warm (i.e. it is not cold, but not fully warm). Sometimes reving up the rpms brings back the pressure to 40 psi, but sometimes it does not work and the pressure stays low. Then suddenly it goes high.
My car has no leaks, however the oil level was low (below the "add" mark). I added 2 qts of oil but it did not change the behavior.
Is this normal? Or do I have a problem? What should I look for?
FYI I use 10W-30 high mileage oil and mopar filters.
Thanks!
In the previous 1-2 years have always noticed that when I get to a stop light, the oil pressure sometimes dropped from the normal 40 psi. It usually never went below 25.
Lately this phenomenon started being more importand and happening more often, I noticed that in several cases the oil pressure drops to low values, around 10 psi. The check gauges light never came on, so far.
It is very difficult to identify a rule of thumb for this to happen, but I would say that this mostly happens when the engine is at low rpms and it is getting warm (i.e. it is not cold, but not fully warm). Sometimes reving up the rpms brings back the pressure to 40 psi, but sometimes it does not work and the pressure stays low. Then suddenly it goes high.
My car has no leaks, however the oil level was low (below the "add" mark). I added 2 qts of oil but it did not change the behavior.
Is this normal? Or do I have a problem? What should I look for?
FYI I use 10W-30 high mileage oil and mopar filters.
Thanks!
Check oil quantity often.
01-19-2014, 12:35 PM
#20
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Year: 1996
Model: Cherokee
Engine: 4.0
Xcessive I seem to have the same issue! The pressure drops to 10 psi after 10-15 mins I turned the car on and when I get to a stoplight. Stays there for a while and then it goes away. Sometimes it comes back, sometimes not. I guess in these cases, when there is not a clear behavioral path, contamination can be the reason.
Regarding one of the questions landude had, I checked my coolant and it is black. So I might have another issue to fix here. What do you suggest to do in these cases (loss of 2 qts of oil in probably 3-4 months, without any spot under the car and black coolant)?
Thanks
Regarding one of the questions landude had, I checked my coolant and it is black. So I might have another issue to fix here. What do you suggest to do in these cases (loss of 2 qts of oil in probably 3-4 months, without any spot under the car and black coolant)?
Thanks
Now, if your coolant it's oily...that's a totally different beast. I'd do a compression check and coolant leak down test asap. If the engine is cool and shows ok, let it warm up and repeat the tests.
01-19-2014, 12:40 PM
#21
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01-19-2014, 12:42 PM
#22
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Year: 1996
Model: Cherokee
Engine: 4.0
Ps. Like everyone else said, change your oil and coolant as well. With out proper coolant and water it will not cool properly. Water is what does the cooling and the antifreeze does the cooling system lubrication, corrosion inhibitor, and obviously keeps the water from freezing. If the coolant is contaminated/old it won't do any of those things.
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