Oil Temperature rising very fast!
There has been multiple threads about this very issue by multiple owners, specially the 2012+ cars. This is an embarrassment for AMG!! (Yes, I have had a case open since Sep 2013 with no resolution - you can read my other posts on this).
The engine doesn't have a limp mode. The engine management does retard timing to cut power at high temperature. I'm not sure that anyone knows exactly when, but people who track their cars report this happens around 275. Limp mode is a transmission feature, where it picks a gear and won't let you shift out of it. It does this under various conditions, with high transmission oil temperature being one. We don't have a transmission oil temperature gauge so it's even harder to know at what temp this happens, but it too seems to be when oil temperature has exceeded 275.
Until you start seeing 260, there's nothing to worry about.
Peaked at 235...what was the average?
When you got to some open road did it drop down? To what?
Doesn't sound like an issue
The Best of Mercedes & AMG
Very seldom 110, only if pushing hard up a steep grade
105 is usually the max
Normal running 95 to 100
Last edited by Ingenieur; Jul 3, 2014 at 06:31 PM.
Keep in mind that a P31 or 507 will run hotter when pushed. Also, the facelift cars with MCT transmissions are reported to run about 15 degrees F hotter than torque-convertor cars. I have no idea why that would be. I can see a small effect from the extra fluid in the torque convertor keeping the tranny a bit cooler, with conduction tending to equalize engine and transmission temperature. (The 44O cooling package upgrades the transmission oil cooler as well as the engine oil cooler.) But 15 degrees seems a lot. In any case, 2012 and later cars run hotter than earlier ones.
~12 miles
Very twisty
Avg speed 50-60 mph
Avg rpm 4000 to 5000 rpm with many redline shifts
Peaks at 220 F 105 C, maybe a few degrees higher 110 or so
12 minutes or so
Ambient 80 F
>2000' ASL
Has nothing to do with the drivers emotional state
Have made the run dozens of times
On the backside downhill back to 95 C within 3-5 minutes
About the only time I really put miles on the car is for enjoyment
Don't think I've seen 230 F often
One must drive within the limits of the machine
Temperatures, tires, brakes, etc
Not many can aquire this skill called mechanical sympathy
Everyone is senna lol in a 4000 lb passenger sedan
I'm sure I could get mine to 240+ but why?
I garantee I can travel just as quickly as the guy who does with my oil running 15-20 deg F cooler
Frantic doesn't mean fast, usually the opposite
Last edited by Ingenieur; Jul 3, 2014 at 07:47 PM.
Car on lift
Remove cladding/access panels
Spray with a commercial grade coil cleaner, be careful can be harsh
Power wash from BEHIND to blow lodged debris out
Depending on state of neglect this can improve system efficiency 10-30%
It's messy but I inspect and wash the chassis at the same time
Usually in the spring to get all the salt and crud off
The temp you see is the sump temp
AFTER it has cooled/lubed the engine
It is then pumped through the cooler and sheds the heat
As much as 20-30 degree depending on OAT, rpm and road speed
So if you see 240 the engine may be getting <220
I let it get up to 190F before getting into it. My car has been great and I haven't had an issue with dramatic oil temp fluctuations. My engine temp stays around 190F.
another OT
for those seeing oil temps 230 range what is the water temperature?
again, the displayed oil temp is sump, not delivered to the engine after cooling
if the water temp is stabile imo everything is OK, the oil is doing it's job by getting hotter, ie more friction and more heat is being generated,
it is then cooled in a thermostatically controlled oil cooler and returns to the engine at a much lower temp
Last edited by Ingenieur; Jul 4, 2014 at 10:46 AM.
I intentionally allowed it to stabilize
H2O 194 f
Oil 212 f
90 C & 100 C
Rock steady on level constant load
Does anyone know for sure the oil temp sensor location?
What is the setpoint of our water thermostat? 90 C?




This tells me the cooling system is keeping up and engine temps are not running away
The oil is working more so it gets hotter
But is cooled to whatever temp the oil cooler stat is set for
But the oil going to the engine is at that temp not the hot sump temp
Just like the water leaving the engine is >195 f before going thru the radiator and being cooled to a mixed/stat regulated 195 f
Is the oil temp sensor in the sump? Most are combined with the level sensor
The water sensor measures the controlled temp, ie after the stat and radiator
Pretty sure the oil temp is before
Last edited by Ingenieur; Jul 4, 2014 at 06:11 PM.
This tells me the cooling system is keeping up and engine temps are not running away
The oil is working more so it gets hotter
But is cooled to whatever temp the oil cooler stat is set for
But the oil going to the engine is at that temp not the hot sump temp
Just like the water leaving the engine is >195 f before going thru the radiator and being cooled to a mixed/stat regulated 195 f
Is the oil temp sensor in the sump? Most are combined with the level sensor
The water sensor measures the controlled temp, ie after the stat and radiator
Pretty sure the oil temp is before
The other source of engine oil heat is the transmission. The tranny is only oil-cooled so engine coolant has no effect. And it gets much hotter in the MCT. On second thought, that's probably the reason that post-facelift engines run hotter. Shifts are enabled by friction material, not a torque convertor so it makes sense that a lot of gear changes will heat things up quickly. The 44O upgrades the transmission oil cooler size even more than it upgrades the engine oil cooler. As far as the transmission is concerned, the engine that it's bolted to is just a big heat sink.
Thr tranny oil and engine oil are two isolated circuits
The thread is about engine oil temp
The tranny cooler has a stat too
Last edited by Ingenieur; Jul 4, 2014 at 07:15 PM.






