Intermittent oil light

Status
Not open for further replies.
A

Arob

Joined
Dec 9, 2006
Messages
57
Location
Iowa
Mercury Mariner 3.0 V6, oil light stays on for 2-3 min. on initial startup, then will come on at idle until revved to 1000 rpm.

Oil was Mobil 1 High Mileage 5W20, with a Motorcraft FL820S.
Miles on the oil and filter, 3k.

I changed out the oil and filter, the light has not come on in the last 100 miles. Could it have been a bad filter? I've always used MC filters, never had any problems. Any thoughts? Thanks
 
Originally Posted By: Arob
Mercury Mariner 3.0 V6, oil light stays on for 2-3 min. on initial startup, then will come on at idle until revved to 1000 rpm.


A typical symptom for a lazy oil pressure sending unit is the light will be on at hot idle, when oil pressure is at its lowest. A lazy sending unit is JUST so slightly out of spec that it triggers a light under those conditions, but not under any others. Normally, I'd say that is your problem.

But you also mention that the light is on for a while on initial start up -- where oil pressures will be high (cold oil, etc). So I'm not sure the sending unit is your problem here. I'd change the oil and filter to rule that out first. I suppose you could change the sending unit (it's probably not expensive), but I think there's something else potentially going on, here.
 
Originally Posted By: Hokiefyd
Originally Posted By: Arob
Mercury Mariner 3.0 V6, oil light stays on for 2-3 min. on initial startup, then will come on at idle until revved to 1000 rpm.


A typical symptom for a lazy oil pressure sending unit is the light will be on at hot idle, when oil pressure is at its lowest. A lazy sending unit is JUST so slightly out of spec that it triggers a light under those conditions, but not under any others. Normally, I'd say that is your problem.

But you also mention that the light is on for a while on initial start up -- where oil pressures will be high (cold oil, etc). So I'm not sure the sending unit is your problem here. I'd change the oil and filter to rule that out first. I suppose you could change the sending unit (it's probably not expensive), but I think there's something else potentially going on, here.


I would agree as well... can change oil - if needed just as a precaution. You can actually test the oil pressure with a gauge if you have one or take it to a shop and prove out that it is the sensor. You also can do a basic layman's test and see if the sensor is oily at all on it's housing - if you know where it is - that would also likely point to a bad sensor. Replacement of it is likely fairly cheap as they usually aren't very expensive to buy - but more likely difficult to get at to replace yourself. Not sure on this application.

BurrWinder
 
What oil did you change to? Thicker than the 5W-20? Maybe the M1 HM did some cleaning and partially clogged the oil p/u screen. The oil change may have drained some of the debris. How many miles on this unit?
 
I did change the oil and filter with the same, M1 HM 5W20, MC 820s, took care of the light. I would add that the engine sounded no different, no knocking, etc with the oil pressure light on.

My first thought was the sensor, found out it is behind the AC compressor, not much fun to get to, but that is probably the next step if the light comes back on. The Mariner has always had either PP 5w20 or M1 5w20. One of my first thoughts was a bad sensor but wanted to get the collective thoughts of BITOG er's.

Miles are 124k. Thanks for the comments!

From previous post in the thread:
"I changed out the oil and filter, the light has not come on in the last 100 miles. Could it have been a bad filter? I've always used MC filters, never had any problems."
 
Probably a bad sender. I would believe if your oil pressure were that low, the engine would be noisy. I would check the pressure with a good mechanical gauge asap just to be safe.
 
Originally Posted By: Arob
From previous post in the thread:
"I changed out the oil and filter, the light has not come on in the last 100 miles. Could it have been a bad filter? I've always used MC filters, never had any problems."


Ha! I think we all missed that part.

I suppose it could be a wonky filter, but I'm not sure what about the filter could cause the symptoms you had. Good to know the light is out either way...
 
If you've always used PP or M1, it's very unlikely you had any sludge blocking the oil p/u. That leaves either sending unit or bad filter as probable. Hopefully the light stays off after this latest change.
 
I missed the part that you changed the oil and filter and the light went off. Could be a combination of a bad filter and sheared oil.

With 125K miles, I'd bump the oil up to a 5W30. It won't hurt anything. And try a different filter than Motorcraft next time.
 
All good ideas, will keep an eye on it and might go to 5W30 PP or M1. That oil pressure sensor isn't going to be easy to get to from a quick look at it. Thanks
 
Status
Not open for further replies.

Similar threads

C
Camshaft and crankshaft sensors
2 3
Replies
40
Views
2K
swampdodo
J
2015 Jeep Wrangler 3.6 V6 Low Oil Pressure
2
Replies
32
Views
3K
350Rocket
rvsarch
Acura Oil Consumption
Replies
12
Views
861
Drew7a
C
Oil change resolved hot idle lower oil pressure., why?
2 3
Replies
53
Views
4K
wlk
L
Low Oil Pressure light came on in a 1994 Honda Accord
2
Replies
29
Views
2K
dumkid
Back
Top