Summary: Because of intermittent low oil pressure displayed especially at idle while hot and resolved by revving, my plan is as follows:
(1) Clean the throttle body,
(2) If problem persists, then replace the oil pressure switch,
(3) If problem persists, then connect a pressure gauge.
I've read many threads here. I'd like feedback on this plan. I.e., would you suggest proceeding differently?
If the problem doesn't reappear after cleaning the throttle body, then would you recommend going ahead with any further steps, e.g. replacing the pressure switch, or just monitor?
Details:
Additional comments/questions:
(1) Clean the throttle body,
(2) If problem persists, then replace the oil pressure switch,
(3) If problem persists, then connect a pressure gauge.
I've read many threads here. I'd like feedback on this plan. I.e., would you suggest proceeding differently?
If the problem doesn't reappear after cleaning the throttle body, then would you recommend going ahead with any further steps, e.g. replacing the pressure switch, or just monitor?
Details:
- 2002 Envoy, 4.2L, original owner, 173,000 miles.
- Several times (e.g. 7/26/2021, 3/8/2023, 7/27/2023, 8/22/2024) especially at idle while hot (weather and engine), the instrument panel oil pressure display (fake value, I know) has dropped to zero and shown "check gauges."
- Usually revving the engine in neutral makes those problems go away.
- I usually use Amsoil 0W-30 or possibly 5W-30. I understand that this low viscosity might contribute to the oil pressure switch reporting no pressure.
- It has the Amsoil remote filter kit (full-flow and bypass filters), with adapter mounted where the stock oil filter goes. (See photo.)
- I have not cleaned the throttle body. See photo from 151,000 mi (when I replaced spark plugs). I understand that dirty TB can cause low idle, thus possibly oil pressure low enough to cause the switch to report no pressure.
- I read that the oil pressure switch is bad 99% of the time (per posts by Mooseman).
- Because of this headache and an unrelated suspension problem, the vehicle has been sitting for about 1 year.
Additional comments/questions:
- Whenever I drain the oil, I'm interested in using my steerable boroscope to try to check the oil pickup screen for being clogged by carbon flakes. I saw a post mentioning that but haven't seen success.
- Because low oil viscosity may apparently contribute to low oil pressure, I'm thinking of changing to 5W-30 or 10W-30, possibly Valvoline Restore & Protect (R&P) like in my other vehicles. I'm near Houston, Texas.
- I see the oil pressure switch is $43 at Rockauto.
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