Oil light coming on -- 2004 Santa Fe 3.5L

I have a 2004 Hyundai Santa Fe with a 3.5L engine and about 80,000 miles on it.
The oil light came on today while I was driving and mostly stayed on. I
went to a nearby gas station and had oil added. He put in 2 quarts, but it looks like it is now over filled by about a 1/2 a quart -- meaning I guess it was about 1 1/2 quarts low before he added the oil.
Now the oil light comes on but goes on and off. I'm guessing the possibilities are: A) a bad oil pressure switch if I'm lucky; or B) the oil pump is failing. I don't think it is leaking oil anywhere or has a worn out engine etc.
If it's the oil pump that is going bad, how big of a job is that on this vehicle? I am sure that is not something that I want to do (especially since I don't even know where the oil pump is located), but is it fairly easy for a dealer or other mechanic to replace the oil pump?
Would it make sense to first try replacing the oil pressure switch? I could probably just do that (I assume), depending on where the oil pressure switch is located.
Thanks.
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JayR wrote:

Try bringing the oil level down to the proper level first.
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Don't overlook other small issues, either. On this engine, the wire for the oil pressure switch runs in close proximity to the A/C- alternator belt pulleys. I've seen cases where the wire intermittently rubs the pulley, causing the circuit to ground and illuminate the oil lamp.
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hyundaitech wrote:

Thanks. I'll check that out.
Here's an update: After I wrote the above message, I got in my car to see if I could buy a Hyundai repair manual at Pep Boys (so I could figure out where the oil pump is etc.) and the light didn't come on at all. I thought maybe it was because the engine was still cool and maybe that kept the oil pressure high enough for the light not to come on. But I decided to just go home and skip looking for a repair manual. This morning -- same thing -- the oil light is no longer coming on.
Right after I had the oil added yesterday, I noticed that the light hadn't gone off so before I left the gas station parking lot I got out and checked the oil level again. The gas station owner came over wondering if there was a problem and I told him the light was still coming on. He had a VERY heavy accent and I could barely understand what he was saying, but he seemed to be saying don't worry. And, I think he was trying to say the light will go off but it may takes a few weeks? That didn't make sense to me, but who knows what he was really saying.
And, also...., I remember the engine seeming a little noisy then and later in the day before I wrote my original post -- like maybe a slight valve clattering noise.
Today, the engine seems quiet and the light doesn't come on.
So, I'm wondering if it is possible that it does take a while for the oil pressure sensor to readjust itself after the new oil was added, and maybe it takes a while for the oil to get to everywhere it needs to go before it quieted the engine? Seems unlikely to me, but as of today, no light and no noise.
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That's not the case. Your oil pressure must be near zero for the oil lamp to illuminate (if everything is working properly). It's turned on by a switch screwed into the engine with a diaphragm which, when oil pressure is applied to it, breaks electrical contact to the block from the wire which is connected to the switch. Once you add the oil, the pressure should return and the lamp should go out. If the lamp remains on, it indicates some sort of problem, either with the oil pressure or something electrical in the circuit.
You won't want to attempt replacing the oil pump unless you're familiar with major repair, as you'll need to remove the timing belt and oil pan to remove the oil pump from the front of the engine.
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hyundaitech wrote:

Thanks Hyundaitech.
I definitely won't be attempting anything with the oil pump -- that would be way out of my league. I also just had the timing belt replaced and a lot of other work (including an oil change) done about 2000 miles ago, so I know what a big job getting to the timing belt is.
Now I'm wondering what may be going on. The oil light has not come back on at all for the past few days and everything seems okay. I'm not sure why I would have been 1 1/2 quarts low on oil since the oil was changed less than 2000 miles ago. And I don't know what caused the oil light to come on in the first place, although adding 2 quarts of oil did see to fix that.
I guess I'll have to look at where the oil pressure switch is and see if anything is going on in that area -- like the wire-near-a-belt issue that you mentioned earlier.
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On Thu, 28 Apr 2011 08:46:34 -0400, JayR wrote:

Whilst you are there, also check the wiring insulation.
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Keep a close eye on the oil level. It is possible the guy refilling the crankcase miscounted and did not fill it (and did not bother to check), a leak, but you probably would have noticed by now, or you suddenly started to get blow by the rings. Used to be valve seals too, but I don't know if that would be affected on your engine.
Car makers do say a quart a thousand miles is considered normal, but I think that is a lot, based on my experience with modern engines. I go about 7500 miles between changes and I've never added oil to either of my Hyundai and only once, that I recall, on my Buick and that has 127,000 miles. I always kept a few quarts of oil around for top-off, but no more.
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Ed Pawlowski wrote:

Thanks. I did have that thought -- how could I have been 1 1/2 to 2 quarts low when the dealership did an oil change 2000 miles ago. There is no sign of any leaking oil -- I looked inside the engine compartment and have been checking under the car where it is parked. So, you may be correct -- the dealer may not have filled the oil properly when they did the oil change.
The good news is that the oil light has not been coming on at all after this last incident, and the oil level is staying the same.
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Oops, the latest update is that now the oil light has been coming on again. I can create the problem by first revving the engine up a few times to a high RPM -- then when it slows down to about 1,000 RPM or less, the oil light starts flickering on and off or comes on steadily. Then if I increase the tach speed a little -- up to about 1,500 RPM or so -- the light goes out. Then back at idle speed the light comes back on or flickers on and off. The oil level is full -- actually a little over-full by about 3/4 quart after a gas station said I needed two quarts when the oil light first came on last week.
I hate the thought of having to get a new oil pump put in since I assume that would cost at least $500 or more and I just had a ton of other expensive work done (timing belt, power steering pump, etc. etc) costing nearly $2000.
Would it make sense to just have the oil pressure switch replaced to see if that is the problem? I have a hunch that the cost of having that done would be the same or not much more than the cost of asking a dealership to just diagnose what the problem is (maybe $100 +/-).
I still like the vehicle (Santa Fe), but it's too bad that I didn't just trade this one in and get a newer one when the warranty on this one ran out (I'm a second owner), and before I started having all of the other "60,000" mile service work and other things done just recently.
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Sounds like the oil pressure is getting low at low speeds, but an oil pump may or may not cure the problem. If it is cause by clearances getting loose, the pump won't make any difference. If, indeed, the pump is work, it will make a big difference.
I had a '71 Ford like that and it has about 50,000 miles when I bought it. . Oil light always came on at idle. I drove it for 5 years and another 60,000 miles like that. Maybe you'd be that lucky, but you just don't know.

What you really want to know is the actual oil pressure. It may be possible to swap out the sending unit with an aftermarket gauge that will give real readings in psi. That will give you peace of mind.
Check out JC Whitney or similar stores http://www.jcwhitney.com/electrical-oil-pressure-gauges/p2014746.jcwx?filterid 7226j1 Less than $20 for gauge and sending unit.
Advanceauto http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/PartSearchCmd?storeId 151&catalogId051&langId=-1&pageId=partTypeList&suggestion=&actionSrc=Suggest&searchTerm=oil+pressure+gauge

That has always been a problem. When do you stop fixing? If this is it for the next year or two, not a bad deal compared to payments on a new model, but if you spend that every couple of months, it would have been better to trade.
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Ed Pawlowski wrote:

Thanks. I have been away from the computer I have that can access newsgroups (another one at work blocks newsgroup access), so I didn't get to write back sooner.
Someone else also recently wrote that trying to get a measure of the actual oil pressure may be a way to diagnose or solve the problem. Makes sense.
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You could do what Edwin suggested, or perhaps change the oil and replace the switch in some order to see if things change. This doesn't sound like a short (as the light flickers when you're at idle), but it's still a good idea to check the wire visually just in case.
In the event this doesn't solve the problem, count on needing a new oil pump. I've only ever seen one case of this, and it wasn't on this engine either, but the pumps are similar. The oil pressure relief valve is spring-loaded in the pump. If it binds just a little bit, too much oil can bypass, causing the condition you have.

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hyundaitech wrote:

Thanks Hyundaitech. I think you may have hit on something here.
I was able to go to http://hmaservice.com and figure out how to see an exploded view of the oil pump, and I could see the spring-loaded oil pressure relief valve. When I saw it, I did think that since it is spring-loaded I wondered if it could get stuck open, although I didn't know what it did.
But, what is interesting to me is how this problem started in the first place, and what I could do to replicate the problem. The oil light first started coming on when I was doing a 60 mile trip on an Interstate Highway at admittedly a higher-than-recommended speed of travel. I just assumed that at the high speed and after travelling for a while, the engine was hot and the oil thinned out and that's what caused the oil light to come on when I slowed down to near idle speeds. Then, the gas station said the oil was two quarts low and added oil. It took a few days for the oil light problem to go away, and then a few days later it happened again. Then, to reproduce the problem so I could show it to a friend, what I would do is (as described above) rev the engine up to high RPM's and then when it slowed down to idle speed the oil light would flicker on and off.
Later, the problem went away for a few more days and then after travelling on an Interstate Highway again, the oil light started flickering again at idle speed.
Now, the oil light has been staying off completely for a few days.
After reading what you wrote, I have a hunch that at high speeds, or when I rev the engine up to a high speed, "maybe" that kicks the spring-loaded oil pressure relief valve into a position where it sometimes binds or sticks a little and stays open -- causing, as you suggested, too much oil to bypass and cause a low pressure condition.
I think this because it would otherwise seem counterintuitive for high speed to cause the pressure to be lower. I would ordinarily think that revving the engine to a higher speed would pump up the oil pressure. But, maybe, the high speed is in fact throwing the spring-loaded oil pressure relief valve all the way into a position where it binds or sticks a little.
For now, since the oil pressure light has been staying off again for a few days now, I think I may just monitor the situation and see what happens next. Or, maybe another oil change wouldn't hurt if in fact something (a small piece of dirt or crud in the oil) is causing the spring-loaded relief valve to bind or stick at times.
We'll see what happens, but I have a hunch that you may have hit on what is causing the problem.
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JayR wrote:

P.S. If I do try doing an oil change, would it make sense to use a thinner grade of oil for this one oil change (such as 5w-30 instead of 10w-40 or whatever) to help clean out anything that may be causing the spring-loaded oil pressure relief valve to stick? I am in New Jersey and we are entering summer weather here.
Or, is there any other way, or additive etc., to help "clean" the engine?
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I'd probably go with a more viscous oil such as 10W-30 just to see if it'll hold enough higher pressure to keep the lamp off. If the relief valve is sticking, changing the oil viscosity won't free it.
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Find out where the oil tap is on the engine block and remove that fitting , then screw in a pressure guage that goes ujp to at least 60 psi. Get someone to read the value while you slowly bring up the RPMS of the engine . Tell us what the values are at idle, 1000, and 2000 RPMS.
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snipped-for-privacy@gmail.com wrote:

.....
Thanks. Makes sense. I haven't tried that, or asked a mechanic to try that yet, but see my reply to Hyundaitech about why (problem is gone again).
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