Yuille36

As some of you may know, I'm a stickler when it comes to maintenance. So, a few days ago I drop my 07 E63 off to have the brake fluid flushed, transmission fluid changed along with it's filter, and rear differential fluid changed.

Now, comes the fun part, wait for it...... The Oil temperature sensor has been fluctuating. The oil light in the cluster will flash off and on, until the oil reaches it's operating temperature of 81 degrees Celsius or about 178 degrees Fahrenheit.
So, we replaced the sensor that I thought was bad, with an OEM piece. Well, the new sensor didn't make one difference. The gauge is still doing the funky chicken.

Does anyone, have a clue what might be going on. Does the sensor wires run thru the SAM. My tech said that he will do some research to see how the wiring is routed. He thinks, it might be a bad pin somewhere but isn't quite sure until diagnosing it.
This sensor feeds the ECM, to tell the car if the oil is too hot, so that the secondary oil cooler fan kicks on. Typically when the oil reaches roughly 215 degrees or more.

This thing is baffling to me, and my OCD isn't helping.

Yuille36

Absolutely, no one has had or seen this issue with there W211 E63?

GinDistiller

This was a response from another thread, posted by someone asking about normal oil temps in his W211 E63:
"Also the Oil temperature display on the cluster will actually flash until the oil reaches 80* C... The owners manual even states to keep the revs below something like 4500 RPM and not be too aggressive until the oil temp is above 80..."

Was yours not doing it before you had that maintenance done? Not sure if he is correct or not as I have an E55, but if he is then what you're seeing is normal.

Yuille36

Thanks for the information, but this I already knew.
My issue is this, the oil temperature that is displayed in the cluster is fluctuating, and not correctly relaying what the actual oil temperature is.
This sends false information to the ECM, as the car doesn't know how hot the oil truly is. As, I mentioned before the Oil indicator will stop blinking once the oil reaches it's operating temperature of 80* C.
My car reaches that and higher, but then the temperature will drop to say 78*C then go back up. How can your oil drop in temperature when you been running it. The oil is nice and hot, and you wouldn't want to touch it.
It currently fluctuate between 77*C to 96*C Now I know the oil is about 86*C as that is what the car normally run at unless the outside temperature is in the high 90* F.
Let me state that this isn't causing the car any issues, just my OCD

But thank you for trying to help out. I will have the car diagnosed, and no one else has any ideas.

GinDistiller

Ah that makes more sense, and yes that would drive me crazy too

Any reason they might have undone a ground strap while servicing? That's my only other thought knowing how sensitive the electrics on these cars are!

Yuille36

No, this issue has been occurring for awhile now. I thought that the oil temp sensor was bad, so we replaced it. But the issue still remains. Personally, I do think it might be a grounding issue, as the connector is a two pin. They will have to trace the wiring, maybe a wire is frayed, the car is 14 yrs old after all. The oil temp always registers, and rises as the engine heats up, then the oil light stops blinking when it hits operating temp, then the temp starts fluctuating up and down, which it shouldn’t. The oil temp should rise, until it stabilizes at a certain temp. Now if you pushing the car then the oil get hotter, but the oil coolers will maintain the temp at a safe level. Now if the oil gets too hot, say above 215* F or more then the secondary oil cooler fan on the passenger side in front of the wheel kicks on full blast, and it’s loud, you definitely know when it’s running.

jpman

my 09 does not have that side fan, but I can attest sometimes mine experiences the same. Are you using any additives in the oil? When was the last time you did an oil change?

Yuille36

The oil was changed last week, when I also changed the tranny, brake and rear diff fluids. And no, I don’t use any additives. The 07-09 engine architecture are the same, so you must have a oil cooler fan as well. You can’t see it, you would have to removed the passenger fender liner to view it, as it sits directly behind the oil cooler. And when it running you definitely know it, as it howls. You might be able to pry the fender liner back enough to see it. Some owner drain both when doing an oil change, but I just drain the primary, as it has a drain bolt, and the secondary cooler doesn’t , just a connection that requires an o-ring. And that could lead to oil leaks if the o-ring somehow get pimched, so I don’t muck with it.

jpman

Yuille,

You are incorrect, while the platform and engines are the same there are some slight variations. All 2009 models do NOT have fans for the fender oil cooler.

back on topic, did you change the viscosity? What weight are you using?

Yuille36

After 14 years, and I didn’t know that. I thought they were the same except for the command display with the SD Card reader.

I’ve been using the same Mobil 1 0W40 European Blend since I bought it. Same oil same weight, nothing has changed.

The car drives fine, but the OCD in me keeps watching the oil temperature like a hawk hoping it will not fluctuate. It’s not the sensor, as it reads true, it’s something else maybe a bad relay?

I emailed my friend that is an AMG Master Tech at a local dealership for answers, hopefully he has some input.

Yuille36

To better illustrate what I’m referring to, the temperature variances are showing between 84* - 87* Celsius, and these two photos were taken within 5 seconds of each other. A 1 degree variance is acceptable to me, but a 3 degree swing isn’t.

jpman

Mine has always done that - I believe it is averaging values multiple times per second. Sometimes I have seen it go above to 90, and depending if I just started it 10 mins or so it will go back down to 79-85...

I will say if I manually shift the car holding revs to about 3k in each gear it stabilizes quicker after about 20 mins of driving and stays anywhere between 83-90 depending on ambient temperature.

what is ambient temp where you are now? Has it changed since you noticed this?

Yuille36

Ambient temp aerators is currently 74* F, and the temp hasn’t changed when I took those photos. I was pushing the car on the way home, and seen oil temps as high as 90* C.

Hopefully, I will hear something back from Jack the AMG Master Tech on Monday.

jpman

no, I meant the temperature since you were not experiencing this issue? A couple of months ago? Is the weather always 74F throughout the year where you are?

I hope you find an answer, I’ll be frank - I do not believe you are seeing much here and maybe chasing a ghost... all you need to know the oil is 80deg +/-5 deg... I doubt that sensor is more accurate than that. As long as the oil is around there you should be good to do spirited driving.

Yuille36

Your right, but my OCD will not let it go until I’ve found a fix. The ambient temperature have varied from 39-70* F ever since this issue surfaced here in Virginia.

The car runs fine, no matter what the gauge says. There was a time not long ago, when the gauge was accurate to a tee. Then, it started fluctuating, so I replaced the sensor and it has never been right since.

Now looking back, I had a oil leak that came from the engine block where the oil cooler lines are, the o-rings went bad. I wonder if that oil embedded itself in the harness wariness the goes to that sensor, is causing this issue? Just thinking out loud here 🤔

jpman

Could the oil thermostat be in the stuck open position?

Yuille36

I don’t know if these cars even have an oil thermostat, as I never heard of it. Not to say that your wrong, But how would this effect the oil temp gauge?

jpman

They do. It’s what controls oil going into the oil coolers or not depending on oil temp.

if it’s stuck open (typically how coolant thermostats fail when in failure mode) this could explain how the fluctuation is occurring so drastically because there is no need for extra cooling.

This could explain why your sensor continues to read as the old one.

This is a long shot though...

Yuille36

Thank you for this, I do believe that you’ve found my issue. Do you happen to know, where this oil thermostat is located?

Farfalho

Any news from your AMG friend?

Yuille36

I emailed him at work, so I’ll have to wait until Monday for his response. As I didn’t want to disturb him at home with his family, about a car issue after work. 😁

Yuille36

Also, I want to say thank you to everyone that has provided their input, your knowledge has been tremendously beneficial to me. I truly think that the thermostat is the answer, will check with my shop as they were trained by Jack the AMG Master Tech.

Yuille36

I've been searching for this elusive oil thermostat, and I'm beginning to think that it doesn't exist, as I can find no references for it at all. No Photos, location or schematics or illustrations.

jpman

https://m.youtube.com/watch?v=G0FR_q4OVB0

also PN 120 on this page

https://nemigaparts.com/cat_spares/e...asis=21107765H

jmb614

Does the coolant temperature also fluctuate relative to oil temperature?