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Ok, this one has me stumped. At idle, the oil pressure is where it is at in the picture. At any speed, and any engine temperture, it will drop slighly below that 3/4 mark. I have checked all week and the oil is not over filled, or low, it has stayed just a hash mark below the FULL line, and when I did an oil change I used 10W-30 (synthetic), Any thoughts on why it is so high? It has the 4.7L V8, automatic transmission and it has 202,000+ miles on it. I bought it with 190,000 miles on it, so I cannot account for its abuse before getting to me.
Taking a stab at it, I was thinking maybe the oil sending unit was clogged or damaged. Or possible the stepper motor for the oil guage is just going bad, but if it were the stepper motor, wouldn’t it exhibit flaky bouncing or be stuck on one reading?
Any help or ideas are appreciated!
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Hi TexasCoder,
Has the oil pressure guage always behaved this way, or is it just recently that the oil pressure guage is now providing a “higher” pressure? Also, have you owned the vehicle for a long time? The oil pressure switch (bad connection at the switch or the switch itself) could provide a false reading on the pressure. I would take a look at the oil pressure switch and its connector. If this is the original switch that came with the vehicle, at 202,000 miles, it could definitely be time to replace.
I believe there is also a way to thread in an external oil pressure guage to monitor as well. This would help verify the “higher” oil pressure reading on the dash. Anyone else have thoughts on this?
The gauge does seem like its reading a bit high, especially for idle. Do what BigC suggested and hook up a mechanical gauge to your block. Look online for what the oil PSI should be and compare the readings. It is very possible that it is the gauge or oil pressure switch that just may be malfunctioning, but better to make sure. When pulling out the dipstick, do you see any foaming/bubbles?
Quoted From BigC:
Has the oil pressure guage always behaved this way, or is it just recently that the oil pressure guage is now providing a “higher” pressure?
The guage has acted this way since I bought it (back in Feb. 2011).
Quoted From BigC:
Also, have you owned the vehicle for a long time?
I have owned this truck since Feb 2011, so about 7 months.
Thank you for the good idea of the external oil guage, that is awesome! I will find one this weekend and test it out. Good thing is, I don’t drive it much, so if there is something weird going on, hopefully the time spent driving it has not damaged anything.
Quoted From wardak33:
When pulling out the dipstick, do you see any foaming/bubbles?Luckily, no bubbles or foam. I have checked for this every time I parked it this week. The oil looks good so far, I keep expecting to see bubbles, foam and/or milky oil. But she has been a trooper.
I am going to find an external oil pressure guage this weekend and hook it up. I will post back on what I find. Thanks for the awesome info!
Great. Thanks for the update. Keep in mind too that someone might have replaced the oil pressure switch with a non-OEM one that is “calibrated” differently…hence a different oil pressure display on your dash. Good luck and keep us posted!
It may be normal, the truth is with a gauge like that you really don’t know what the oil pressure is with a gauge like that. Anytime you suspect an oil pressure issue the first setp is to put an analog gauge on the engine in place of your sending unit and observe the pressure, compare that to spec and see if you are in range, if you are then chalk it up to a gauge problem and either install a different gauge or just ignore the one you have. Also my experience with older engines that might leak a little oil is that if you run synthetic it’s going to make the oil leaks worse, I know you are trying to do right by your engine but the truth is the only real benefit from running synthetic is extended oil change intervals, the engine was designed to run on regular oil and you would be fine with that if you changed it regularly, I say save your money on the synthetics.
Eric
Is it safe to assume that the best place to attach an external oil pressure gauge is at the threaded access point for the oil pressure sending unit?
Yes. that would be the place for an oil pressure gauge. if you are installing a permenant one you can put a tee fitting in so you can still use the factory sender. Quoted From spelunkerd:
Is it safe to assume that the best place to attach an external oil pressure gauge is at the threaded access point for the oil pressure sending unit?
I agree with Eric. In school, I was taught that those gauges are usually about as effective as an oil light that comes one when yer way low on oil at best. Everyone’s suggestions to use an analog gauge to actually see what the pressure is is dead on in my opinion.
I wanted to give an update to this post. I do not have the money to buy the tools I need to diagnosis this properly, but I did want to give some feed back as to what I have found so far.
1) A couple of months ago I changed the valve cover gaskets, they were leaking. The passenger side was more aggressive, in consistantly leaving a small dime size puddle on the exhaust manifold when you would shut the vehicle off and let it set for about 15 or so minutes. After changing the gaskets, and fixing the leaks, the oil guage started behaving. Although it would occassionally spike up and stick….I left it, as I still wanted to buy an external pressure guage and diagnose it a little further.
2) Fast forward about 3 months to today (11/05/2011), when the temps outside were 30-40 degrees at 7 this morning. I jumped in the car, let it idle for about 5 minutes, then headed to run my errunds. At about 10 minutes into the drive I get a “DING DING” buzzer noise and notice my “Check Guages” light was on. Thanks Chrysler for the idiot lamp 🙂 I immediately scan all guages and find that the oil pressure is bottomed out…if it did not have that stop pin, I am sure it would have dropped all the way down to point due south 🙂 BUT….after about 2 minutes of the Check Guages lamp, it went off and the oil guage was reading normal. It did this act about 4 or 5 more times, and then I noticed that once the engine was at normal operating temps, the guage was solid and did not waver or drop.
This may be a faulty guage, and I cannot find an recalls or TSBs on the issue, but as soon as I get the money to buy the pressure guage I will trouble shoot the issue a little further and post my findings.
Thanks guys for all the great ideas and help, you are AWESOME!!!
Personally I’m leaning toward a gauge or wiring problem, especially since it happened just after you did the valve cover gaskets, if memory serves there isn’t a lot of clearance under there to work in and it’s entirely possible that a wire or connector got bumped causing the problem. You might want to go back and check the wiring around the pressure switch and see if you can follow the wiring to see if it goes anywere near where you were working. It’s still not a bad idea to check the actual oil pressure with an analog gauge just to be on the safe side. Good luck.
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