W177 - Gearbox oil temperature

[MMTech]

Car:
Mercedes A200 - Automatic
2018 - 23.000 km.

How long should it take before the gearbox oil should be up to operating temperature? - The "blue line" on dash says 50c for minimum temperature before the car should be pushed. After 30 kilometers, the temperature is still only at 30-35c.

Should it really take that long to heat up the fluid? - Or could it be the wrong fluid or a sensor error?

 

[AMGeed]

I believe the sensor is monitoring your engine oil temperature, not the ATF.
Optimum engine oil temperature is around 90C so I would suspect your oil temperature sensor is faulty.

 

[jasonh]

It depends a bit on the outside air temperature but in the UK at between 10C and 20C I'd expect the engine to be fully up to temperature in around 5 miles for petrol engines and 10 miles for diesel.

With the numbers you are seeing it must be the sensor.

 

[MMTech]

Today it was about 15c outside - The engine temperature gets to 70c fairly quick, about 10 km today. But the gearbox oil temp, as shown in the picture takes forever, as in +40 km.

Hmm, might have to take it to the dealer.

 

[AMGeed]

Apologies for my earlier reply. I must own up to not seeing a w177 dash before and didn't realise transmission temps are now displayed.
You are probably looking at a faulty sensor in any case. Yes, a trip to dealer is in order to diagnose.

 

[jasonh]

That is odd, I did actually assume you really meant the engine oil temperature but the gearbox oil won't be far behind.

I know a fair bit about BMW's not so much MB. The BMW's have a thermostat and heat exchanger between the engine coolant and the gearbox. It works both ways so the engine coolant quickly brings the gearbox oil up to temperature but if the gearbox oil gets too hot it can dump heat into the coolant which in turn loses the heat through the radiator.

On an idling BMW the gearbox oil will be at 40C (the oil level check temperature) in 2 or 3 minutes from a cold start and that's parked.

If there's a similar set up you your car the thermostat could be stuck closed. Or it could be the sensor.

 

[AMGeed]

Mercedes oil levels are checked at 85C so a lot warmer than BMW.

 

[MMTech]

Thanks - Will take it to the dealer and have them check it out.

 

[grober]

Wayback Machine
There's a cooling module associated with this gearbox to control transmission fluid temp.

 

[st13phil]

Today it was about 15c outside - The engine temperature gets to 70c fairly quick, about 10 km today. But the gearbox oil temp, as shown in the picture takes forever, as in +40 km.

FWIW, at that sort of ambient temperature the transmission oil temperature on my A220 W177 takes a similar distance / time to reach the “normal” mark, so I doubt there's an issue.

That's the trouble with having additional gauges: people worry!

 

[MMTech]

#10 - Interesting, maybe there is no issue. I agree about the gauges. If there were no gauge, i would assmue the gearbox oil would be up to temperature when the engine oil was. But i also assume they set the mark at 50c for a reason, so how can i not worry/wait forever for it warm up.

 

[Bellow]

What type of transmission does it have - eg. conventional torque converter epicyclic, DSG, CVT?
I'd only expect the first to create significant heat - and maybe a CVT if employing a torque convertor.

Trans oils don't see the heat of pressure fed plain bearings or cool the pistons' undersides as engine oils do. There will therefore be a large difference between the two oils' temps.

 

[st13phil]

What type of transmission does it have - eg. conventional torque converter epicyclic, DSG, CVT?

It's a Dual-Clutch 'box.

I think one of the issues is that many people are used to seeing the engine coolant temperature rise fairly rapidly, and then think that everything's up to temperature - which is far from the truth.

When I had my bi-turbo E63's, on a typical morning with 12c-15c ambient the coolant would be up to temperature in around 3 miles from cold start while the engine oil temperature would take a further 7 or 8 miles to hit "normal". They didn't have a transmission oil temperature gauge, so I don't know how much longer that took to get up to temperature, but judging by my wife's SLK55 (which does have a transmission oil temperature gauge), I'd say anything between a further 6 to 10 miles - and the SLK has a torque converter 'box.

 

[Bellow]

It's a Dual-Clutch 'box.

In which case the temps will be in line with a manual box. Even there (aside from overly thinning) with heat, the only real danger is accelerated attack of yellow metal synchro cones but with the correct oil, that shouldn't occur. Too cold just means heavier shifting at the lever.

I think one of the issues is that many people are used to seeing the engine coolant temperature rise fairly rapidly, and then think that everything's up to temperature - which is far from the truth.

I reckon on at least the same mileage again for engine oil temp to reach normal.

When I had my bi-turbo E63's, on a typical morning with 12c-15c ambient the coolant would be up to temperature in around 3 miles from cold start while the engine oil temperature would take a further 7 or 8 miles to hit "normal". They didn't have a transmission oil temperature gauge, so I don't know how much longer that took to get up to temperature, but judging by my wife's SLK55 (which does have a transmission oil temperature gauge), I'd say anything between a further 6 to 10 miles - and the SLK has a torque converter 'box.

I can 'read' my engine oil temp by the falling oil pressure on the gauge. Trans oil should be following a similar trend (but with lower values) as similar to eng oil, it is first heated by the coolant. But there's no heat in the main rad until the coolant thermostat opens - so a three mile lag right there irrespective of anything else.
My truck is a weird thing in that once it has passed the trans oil through the main (coolant) rad's saddle cooler it then directs it to another rad for double cooling but accepting that some of the heat it (beneficially) gained during warm up is sacrificed. That truck is so weird as to have in total six coolers (air con rad, coolant rad, engine oil saddle cooler, trans oil saddle cooler, trans oil rad, and cooler for PAS fluid (which also powers the brakes). Seeing the last one in that list was an eye-opener! (Just to add to the weirdness, it has duplicated AC and heating front and rear. 40 foot of AC pipes and the same again for heating).