Should my oil pressure gauge ever be this low?
- Thread starter Kathy
- Start date
Absolutely normal. The oil pump is mechanically driven by the engine so the oil pressure goes up and down in step with the engine rpms.
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Similar type question I've always had is this:
When you start a vehicle, should you wait till the oil has had some time to get dispersed? Or just take off? I usually use my RPM's as a gauge to when to put it in gear to go. When you start they're like 1200-1300 and then they settle to around 800-900. That's when I go. I just reasoned that since starting the vehicle is the hardest thing on the engine then I should give some time for oil to get throughout. May not matter though???
When you start a vehicle, should you wait till the oil has had some time to get dispersed? Or just take off? I usually use my RPM's as a gauge to when to put it in gear to go. When you start they're like 1200-1300 and then they settle to around 800-900. That's when I go. I just reasoned that since starting the vehicle is the hardest thing on the engine then I should give some time for oil to get throughout. May not matter though???
Yep, very normal as everyone else has said!
These oil gauges are notoriously inaccurate to begin with, so I wouldn't pay much attention to them.
These oil gauges are notoriously inaccurate to begin with, so I wouldn't pay much attention to them.
While common this is not a "normal" condition.
This is sign of things wearing out. Mine did the same thing for years, eventually coming off the highway with everything hot the gauge would drop right off, the low oil light came on and the alarm sounded. Touching the gas brought the pressure back up. Some recommended a new oil pump but the guys who seemed to be experienced said that would only be a temporary switch as the problem was also affected by a general loosening up of everything mechanical.
I put in a new long block. Getting a motor with a new pump and all clearances back to factory new. Also solving the valve cover and rear main seal leaks. I just tried it. Engine hot or cold started the engine and watched the oil pressure climb to full pressure at idle. Blipping the throttle barely moves the oil gauge needle.
So no, not normal. Just a sign of a miled out motor performing far below "new".
I also noticed with the old engine, parked on a 12% grade in gear, the Jeep would "creep" downhill. Probably less that an inch an hour but enough to get your attention. And downhill using the engine rather than the brakes.... on routes I drive often, crawling down a steep drop off, there is way more, better compression, control now.
But amazingly, I cannot tell if acceleration improved with the new engine. Should have done some acceleration tests before the swap to compare.
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I bought my Sport brand new in 2000 and just went over 75k miles. Mine has done this since day one, it's perfectly normal.
chattycheech
New Member
I have a 2003 Sahara 4.0. It has 44K miles and just started doing this. I checked it with a mechanical pressure gauge and the needle didnt fluctuate at all other than what is expected with changing of the idle/RPM. So, I put on a new Sending unit and NOTHING changed. Well, actually after that, I started getting the check engine light on, so I scanned it and only code I got was a P0118, which is coolant temperature sensor voltage too high....(the only dash lights I got with the dropping oil pressure initially was the red 'check gauges' light/beeping when it bottomed out.
So, I changed the Coolant temperature sensor and Voila.....NOTHING!
Now I have a rough idle and some 'missing', especially when its cold, check engine light, and a Dancing Oil pressure gauge. (There are absolutely no changes in the sound of the engine either with the oil pressure dropping. I thought about installing a new oil pump, but dont think mine is faulty)
Please help.....And I am certain this TJ has been babied its entire life and with such low mileage, I seriously doubt that the mechanicals are worn out!
So, I changed the Coolant temperature sensor and Voila.....NOTHING!
Now I have a rough idle and some 'missing', especially when its cold, check engine light, and a Dancing Oil pressure gauge. (There are absolutely no changes in the sound of the engine either with the oil pressure dropping. I thought about installing a new oil pump, but dont think mine is faulty)
Please help.....And I am certain this TJ has been babied its entire life and with such low mileage, I seriously doubt that the mechanicals are worn out!
My OP gauge stays fairly consistent from idle to full throttle. All that tells me is the gauge and sensor are not very sensitive. Fluctuation from idle to under load should be expected. Generally speaking, the tighter the engine (main/rod bearings etc), the better the pressure assuming your pump is good. My engine has a bit over 90K and sounds and runs fresh. If your pressure actually dropped too low, your ears would probably warn you before you noticed the gauge.
Yes, newer TJ oil pressure gauges were reprogrammed to remove the normal ups & downs of oil pressure. So long as the actual oil pressure is within normal limits, the gauge is programmed to stay at its mid-scale position.
This was done because too many new Jeep owners buying the new TJs were complaining about the oil pressure going up & down & the dealers couldn't convince them it was normal. They were the ones buying their first vehicle with a real oil pressure gauge & they were ignorant of how they are supposed to work. The factory was forced by all the dealer complaints to program the normal ups & downs out of the gauge and present a steady mid-scale reading so long as it was actually ok.
My '97 oil pressure gauge worked as it should, it showed the true constantly varying oil pressure. I'm guessing the reprogramming happened around 2001-2002 or so.
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That is interesting!!! Did not know about the reprogramming. Now, I am thinking, other manufacturers do the same thing. I had never noticed the large gauge fluctuations on other vehicles I owned, just the Jeep.
tquig01
TJ Enthusiast
One of my first cars was a 77 Firebird with a 350 I had rebuilt. It had an old school mechanical gauge with a tube running from the block to the back of the gauge. It fluctuated just like my 2000 TJ, lower at idle / higher with more RPMs. Oil pressure is not consistent in engines and this is normal as Jerry pointed out in a different thread.
TrailYacht
Member
Double check the obvious, as in all the work you just did make sure nothing is odd or loose.
You can try reset the PCM back into adaptive learning, as if the vehicle was new. If you haven’t already. This would be more significant due to the coolant sensor as it affects fuel lean.
Also, are they Mopar sensors? They should be..
Good luck!
My 2001 Sport came equipped with the varying oil pressure gauge new from the factory. One thing I don't like and JMT pointed out...at a cold start-up the RPM's jump to around 1300 which I think is too high...especially during the winter months.? I really miss the old "idle adjust" screw where you had more control of start-up RPM's.