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Discussion Starter #1 (Edited)
97 2.5 TJ, 5 spd manual, Euro spec.
During day to day driving, including city driving, the oil pressure indicator sits slightly above the 1.5 mark, at idle.

When driving it varies around the 3 mark, depending on the rpm. No issues there.

After driving on the highway, at high rpm, for a longer period of time, when I come to stop and go traffic, at idle, the oil pressure indicator slowly goes to 0 and the check gauges light comes on.

If I rev it slightly, it will immediately go up, but still come down slowly to zero. There is no change in the engine sound, seems to run the same. If I continue to drive on the highway, high rpm, all seems fine, no issues with the indicated pressure.

Once it cools down and I restart it, the pressure indicator acts normally.

I have recorded a video with the behavior:

I am thinking either a bad pressure sensor or pump. Although the pump should act up all the time, not just when driving long distance at high rpm.

Any advice is appreciated
 

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What grade oil are you using? Is the level ok? The hotter the engine the thinner the oil will be and lower the pressure can drop at idle. The best way to check actual pressure is to fit a mechanical gauge. Using a T-adapter it can be compared to the reading on the dash.

I had bad readings years ago and after confirming pressure, I cleaned the sensor by spraying brake cleaner into the orifice and blowing across the hole with an air line. It's been fine ever since.
 

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It is absolutely 100% normal for a real oil pressure gauge as your '97 has for the oil pressure to go up and down in nearly direct step with the engine rpms. The oil pump is engine driven so the higher the rpms the harder the oil pump is pumping. 10 psi per thousand engine rpms is a good rule of thumb for acceptable oil pressure.

Too few younger people understand how oil pressure works since most cars stopped including an oil pressure gauge.
 

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Discussion Starter #4
What grade oil are you using? Is the level ok? The hotter the engine the thinner the oil will be and lower the pressure can drop at idle. The best way to check actual pressure is to fit a mechanical gauge. Using a T-adapter it can be compared to the reading on the dash.

I had bad readings years ago and after confirming pressure, I cleaned the sensor by spraying brake cleaner into the orifice and blowing across the hole with an air line. It's been fine ever since.
10W30 as per the book. Level is ok, I realize that oil get thinner with the increase in temp, but zero when the engine is running is not a good pressure.
It's hard to confirm the pressure, because I cannot replicate it at will, sometimes it's fine.

It's a good idea with the mechanical gauge, will look into that.

It is absolutely 100% normal for a real oil pressure gauge as your '97 has for the oil pressure to go up and down in nearly direct step with the engine rpms. The oil pump is engine driven so the higher the rpms the harder the oil pump is pumping. 10 psi per thousand engine rpms is a good rule of thumb for acceptable oil pressure.

Too few younger people understand how oil pressure works since most cars stopped including an oil pressure gauge.
I understand and I know it's normal for pressure to go up or down, depending on many factors (oil grade, temp, load, etc). But 0 PSI at idle is not good, as you also mentioned.

The idea of the post was to see if anyone has experienced similar behavior and maybe help narrow down the culprit. I am in Europe so parts take a long time to come and I don't want to order a whole truck load of parts, when only one is at fault.

A few years back I had a Vitara, the engine temp indicator would go down to zero when applying throttle and would come back to normal readings when idle. It was obviously an electrical issue with the sensor, changed it and all was fine.

Here I tend to think it is the sensor, but considering the high rpms and heat, I thought maybe the pump could also play a part.
 

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Change the sender before worrying its something else. And don't use a store brand or other cheap replacement m
 

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Had a similar roblem with my '97 TJ. Check the electrical connection to the oil pressure sender. Cleaning that fixed my bad indication.
 

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A few weeks ago I had the same problem, normal psi at idle was 40#, all of a sudden it's 5 psi at idle. Changed the sensor and that fixed the problem. Now here is the kicker, it was Sunday so I got one from Advanced Auto, bad move, it has quit after 6 weeks. They will replace it, but as Jerry said several times (and I ignored) get one from Mopar. This was the original sensor with 184,000 miles.
 

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Discussion Starter #8
Had a similar roblem with my '97 TJ. Check the electrical connection to the oil pressure sender. Cleaning that fixed my bad indication.
Yup, cleaned the connections with a contact cleaner spray and it seemed ok for the return trip. I will order a new one just in case.

A few weeks ago I had the same problem, normal psi at idle was 40#, all of a sudden it's 5 psi at idle. Changed the sensor and that fixed the problem. Now here is the kicker, it was Sunday so I got one from Advanced Auto, bad move, it has quit after 6 weeks. They will replace it, but as Jerry said several times (and I ignored) get one from Mopar. This was the original sensor with 184,000 miles.
Will try to find an OEM part, problem is in Europe we don't have access to a very large variety of parts.
 

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Discussion Starter #9
Longer term update, after using a contact cleaner spray the sensor is working fine, no more issues.
 

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Thank you for the follow up. It is always good for the forum to know what worked.
 
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