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oil level light

There have been a couple of threads on this topic in the past, but none seemed to come to a resolution, so I'm going to post this problem I'm having --

I have a 1982 928S (has spoilers so I think that makes it an S), which I bought a few years ago and been driving only periodically as I am trying to restore it into working order (timing belt project, CV joints, A/C conversion to R134a, climate control problems, etc).

my current issue is the Central Warning Light and oil LEVEL light come on periodically, typically when the engine is under load (during acceleration up an incline especially, but also occurs when level). My oil pressure is steady 4-5 bar, oil pressure light does not activate. No lifter noises from engine.

Of course I have changed the oil, replaced with a new filter, 20/50W oil. my level is up to the highest mark on dipstick. I check all the wires leading to the oil pressure sending unit (replace the connectors which were corroded) checked the wire leading to oil level sender unit (perfect condition) and even removed the oil level sender unit to verify that it works.

I've looked at all my grounds and 14 pin connectors, cant seem to find any significant corrosion.

I'm really at a loss here and wondering if its just a Central Warning System gremlin or if there really could be an oil system issue (like oil not returning to the pan quickly enough?!). My oil pressure seems strong, so I'm feeling like I'm safe to drive, but obviously a bit concerned about that as well.

Hoping for some ideas! Thanks!
Old 09-11-2017, 05:19 PM
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It is a known problem for oil to pack into the heads of the 928 engines at higher RPMS. Is that when you are experiencing the warning?
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Old 09-11-2017, 06:22 PM
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Is 20W50 oil recommended by Porsche? I use to put that in my Harley.
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1986 928S
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Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L
Old 09-12-2017, 03:47 AM
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Quote:
Originally Posted by harborman View Post
Is 20W50 oil recommended by Porsche? I use to put that in my Harley.
20w50 is what we use down here in God's country. I'm not sure where the OP is, but if he's in a southern clime, that is what he should use.
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Grand Prix White 1994 GTS AT (The GTS)
Cobalt Blue 1989 S4 AT (The Blue Car)
Indishrot 1984 Euro S AT (The Stepson)
Black Metallic 1984 Euro S 5 speed (The Schwartz)
Old 09-12-2017, 08:06 AM
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western Pennsylvania, but summer driving...20/50 is listed as optimal. this occurs around 3000 rpm so not really pushing it
Old 09-12-2017, 06:10 PM
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How does your engine harness look? Are there places of corrosion especially around the 14 pin connector? It could be merely an intermittent short in a bad part of the harness.
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Grand Prix White 1994 GTS AT (The GTS)
Cobalt Blue 1989 S4 AT (The Blue Car)
Indishrot 1984 Euro S AT (The Stepson)
Black Metallic 1984 Euro S 5 speed (The Schwartz)
Old 09-13-2017, 08:07 AM
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14 pin connector looks good but I cleaned it with some electrical cleaner and an airhose to be sure (see photo).

the 20/50W oil is recommended (see photo from my manual). in fact, i did have 10/40w in the engine initially and still had the same problem.

you mention that oil tends to pack in to the heads, but i just cant believe that 2+ quarts of oil could(i figure that the oil level would have to be about 2 quarts down for the switch to activate, given that there's 1.5 quarts between hash marks on the dipstick). I even decided to try adding an extra 1/2 quart overfill but this still occurs.

some one suggested to me that if I remove the wire from the sending unit, and the problem goes away, then it the sending unit is faulty. In fact, i did remove the wire and the problem went away, suggesting its not an electrical issue. However, I removed the entire oil level sending unit, but it seems to be working well, suggesting that the oil sump is dry!

I'd hate to remove and rebuild the heads/engine but i'm thinking that there is something wrong in my oil system internally like a plugged oil channel

heres some photos:



Old 09-13-2017, 12:57 PM
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If you removed the sensor from the circuit and the light did not reoccur, then it would stand that the sensor is faulty.

I've never heard of an oil level sensor going bad, but there's always a first time. Call 928 Intl for a used replacement part. IIRC, 928 Intl offers a year warranty on their used parts.
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Cobalt Blue 1989 S4 AT (The Blue Car)
Indishrot 1984 Euro S AT (The Stepson)
Black Metallic 1984 Euro S 5 speed (The Schwartz)
Old 09-13-2017, 01:35 PM
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Sounds like a gremlin rather than an actual oil level / flow issue.

Grounding the sensor to see what the dash does, as suggested above, seems like the next step.
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1967 912 (now w/ 50% few random holes in it)
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Old 09-15-2017, 03:58 AM
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Put a mechanical gauge on it for a test.
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1986 928S
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Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L
Old 09-15-2017, 04:22 AM
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Not sure what is meant by "mechanical gauge"...When I ground the wire leading to sender unit, the light on dash and central warning light comes on with engine running...when I remove the wire and drive the vehicle there is no alarm/light. This seems to all point to a bad level sender unit. However, when I removed the sender unit and tested with multimeter, it seemed to adequately close the circuit when I moved the float. Maybe the float or calibration is bad. I guess my only choice is to change the sender unit.

From everyone's responses ( and advice from my dad), if there's adequate oil on the dipstick and oil pressure good, then unlikely to be an oil system problem.

I'll replace the sender unit and update you all. Thanks for the input!
Old 09-15-2017, 04:41 PM
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Keep us posted, and be gentle with her until you know for sure the sender is the issue.

Fingers crossed!
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1967 912 (now w/ 50% few random holes in it)
911 w/ 3.2 (ugly but kinda fast)
1974 914 (3.2L swap underway)
1984 928s (with S4 engine and suspension)
1987 928S4
Old 09-15-2017, 05:39 PM
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Quote:
Originally Posted by 928JimL View Post
Not sure what is meant by "mechanical gauge"...When I ground the wire leading to sender unit, the light on dash and central warning light comes on with engine running...when I remove the wire and drive the vehicle there is no alarm/light. This seems to all point to a bad level sender unit. However, when I removed the sender unit and tested with multimeter, it seemed to adequately close the circuit when I moved the float. Maybe the float or calibration is bad. I guess my only choice is to change the sender unit.

From everyone's responses ( and advice from my dad), if there's adequate oil on the dipstick and oil pressure good, then unlikely to be an oil system problem.

I'll replace the sender unit and update you all. Thanks for the input!
A mechanical oil gauge is one that has a small oil line going into the gauge, does not use a sender and is not electrically operated. There are plenty of them on Ebay.
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1986 928S
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All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L
Old 09-16-2017, 04:03 AM
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Harborman,

It's the oil level gauge on the oil pan that he's having trouble with, not the oil pressure gauge.
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Grand Prix White 1994 GTS AT (The GTS)
Cobalt Blue 1989 S4 AT (The Blue Car)
Indishrot 1984 Euro S AT (The Stepson)
Black Metallic 1984 Euro S 5 speed (The Schwartz)
Old 09-16-2017, 10:21 PM
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Quote:
Originally Posted by stepson View Post
Harborman,

It's the oil level gauge on the oil pan that he's having trouble with, not the oil pressure gauge.
OK, I thought he was having pressure issues.
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1986 928S
32 valve engine
All stock, automatic, 539 Weissgold Metallic, 70K original miles, Hankook Ventus 2 tires.
Previously owned: 67 Vette, 427 L88 Stingray, 74 De Tomaso Pantera L
Old 09-17-2017, 03:52 AM
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I'm opening up this thread again, unfortunately...i purchased a new oil level sender unit and installed, but continued to have the problem. To restate it:

Under hard acceleration and over about 3000rpm, the oil level light comes on. I do not lose oil pressure and there is no change in the engine performance. This has occurred with both 10w/40 oil and 20/50w (latter is the recommended one in my climate)

I'm convinced that there is a problem with oil return, but not low enough to dry out the pump intake.

Frustrated but not willing to just accept it, I just recently decided to take off the oil pan to inspect it. (the gaskets leaking anyway, so it needed replacement). It went pretty smoothly, a little pain getting the actual cross frame member to drop and squeeze out of there, but successful nonetheless.

I dont see any special obstruction to oil return, but was surprised the small size of the actual sump and also that all the oil return has to go through a mesh prior to entering the oil sump where the oil level switch is located. I wonder it this mesh/screen is the issue.

I have a couple of questions, if anyone out there has some opinions on these:
1. has anyone heard of poor oil return through the screen/mesh, and should this be replaced? it really wasnt gunked up or anything
2. how does the screen/mesh fit with regard to the rubber boot of the oil pump intake tube? it seemed that the screen hung up on the boot when I removed the oil pan. does the boot have to go through the screen completely when i install the oil pan? Should the rubber boot be replaced?
3. thoughts on a thinner oil to aid with return? (10/30w perhaps?)
4. any where else the oil return could be hung up?
5. are there any other projects (other than replacing the engine mounts) that i should address at while I have the oil pan off?

Thanks for any input!
Old 03-11-2018, 12:41 PM
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Quote:
Originally Posted by 928JimL View Post
I have a couple of questions, if anyone out there has some opinions on these:
1. has anyone heard of poor oil return through the screen/mesh, and should this be replaced? it really wasnt gunked up or anything I would clean the screen with Brake cleaner and call it good
2. how does the screen/mesh fit with regard to the rubber boot of the oil pump intake tube? it seemed that the screen hung up on the boot when I removed the oil pan. does the boot have to go through the screen completely when i install the oil pan? Should the rubber boot be replaced? The boot(sump tube)goes into the bottom of the pan through hole in the screen
3. thoughts on a thinner oil to aid with return? (10/30w perhaps?)Don't do it.
4. any where else the oil return could be hung up? Oil return problems, (i.e. oil packing into the heads) is a problem more for 32V cars at RPMs over 6000. This is not the problem you are having.
5. are there any other projects (other than replacing the engine mounts) that i should address at while I have the oil pan off? Replace the seal at the top of the sump tube WYAIT . Replace the steering rack bushings with Delrin bushings. Your car will steer much crisper than before.

Thanks for any input!
Jim, I think you have a wiring/electrical issue than manifests itself upon hard acceleration. Take the 14 pin connector loose and test the wires that feed the oil level sensor for grounds and shorts. If the wires test okay, it could be a problem with your Central Warning computer located under the foot rest in the driver footwell.
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Cobalt Blue 1989 S4 AT (The Blue Car)
Indishrot 1984 Euro S AT (The Stepson)
Black Metallic 1984 Euro S 5 speed (The Schwartz)
Old 03-11-2018, 02:08 PM
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Thanks John for the tips --
Will definitely address the steering bushings.
I am just not convinced of an electrical issue with this --> first of all, the problem did not occur with the oil level wires grounded out, nor when disconnected. i'd think if it was grounding out somewhere, it would occur whether or not the wire was connected to the sensor (David from 928 specialists advised me on this). i replaced the sensor ($200) just in case there was a weird fault in the sensor. I also just cant attribute this to the central warning system, as it is very predictable and reproducible, occurs predictable under the same conditions. do you know of a way to test the central warning system, or does a person just replace it and hope for the best?
Old 03-11-2018, 03:17 PM
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There is a way to test it, but I am not that familiar with the procedure. It should be in the WSM.

Just a thought, Jim, and I don't mean to ask a stupid question, but thinking about when your issue arises, it would seem that your oil in the sump is pushed to the back of the pan during the hard acceleration, correct?

Are you absolutely sure that you have enough oil in your engine?
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Indishrot 1984 Euro S AT (The Stepson)
Black Metallic 1984 Euro S 5 speed (The Schwartz)
Old 03-11-2018, 08:04 PM
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Jim, no matter what, do not switch to a lighter oil. 20W 50 is what you need in our region.

I think your problem lies wholly with the gauge. These are known issues. Have you ever done a pod cluster refresh? Very easy to do, and cures most of these gremlins. At this point, you have eliminated any potential mechanical problem. The design of the engine is fine as far as oiling goes and street driving. Your issue is undoubtedly related to the gauge or the ground at the pod. I'm thinking the guage triggers the central warning light to light up.

Here's a write up on the cluster refurbish: https://members.rennlist.com/sharkskin/Pages_SA_R22-PodElectricalRefurb.htm. Also, while your at it, here's the write up for the CE panel refurbish: https://members.rennlist.com/sharkskin/Pages_SA_R04-Bzzzzzt.htm.

They are both easy day jobs, and may cure a number of issues. Also, clean the grounds to the panel well, and the pod. Additionally, clean the big ground wire from the engine block to the engine bay on the lower passenger side - make the contacts nice and shiney. Do all of these things then see if there is still an issue. They cost nothing, and should be considered pat of regular maintenance anyway.

Lastly, the "S" model in the US came out in '83. If your car is a US spec car, you have the "performance package", which was an option beginning in 81, and included the spoilers and the bigger "S" brakes. You motor is a 4.5l, and the "S" motor is a 4.7 l. I'm in Pittsburgh (north hills area) feel free to reach out.


Edit: here are two more write ups for the pod - Dwayne's famous tutorials: http://www.dwaynesgarage.norcal928.org/Pod%20Removal%20and%20Instrument%20Cluster%20Repai r%20I.htm; http://www.dwaynesgarage.norcal928.org/Instrument%20Cluster%20Repair%20II.htm. Even though these are for a different year car, most of the info still applies.
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Last edited by Linderpat; 03-12-2018 at 04:42 AM..
Old 03-12-2018, 04:34 AM
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