G350 Bluetec - P0218 The oil temperature of the transmission is too high.

[johanmaree]

Morning Guys

I have this on my G. It has lost power and would not engage when on the freeway after 77km driving at constant speed. After cooling down all was OK. In town driving when it (supposedly) gets hot, gear shifts become erratic. Oil levels are good and no leaks.

- Is there perhaps a sensor that is not doing its job?
- Will a radiator clean solve the issue? I am considering this as a first step.

 

[Alan]

Hi Johan, sorry to hear you are having issues. I did a google search and came up with this:

https://autovfix.com/p0128-mercedes-causes-fix/

Seems it has to do with temperature not reaching operating temp?

Hope you can easily solve it.

 

[johanmaree]

Hi Alan

In my case it is certainly too hot. When stuck on the freeway there was a vapour coming from below. Posibbly from the gearbox breather and ons could smell HOT oil while engine coolant on the instrument cluster showing 90°.

 

[Alan]

Hmm, I think I would first check oil level in gearbox and then move to oil lines to and from radiator and check all are free as well as radiator. I don't know the 350. but is the oil cooler in one of the header tanks of the main radiator? That is only a small tube inside a tube. But I do not really think it is a blockage. Possibly a filter in the gearbox needs replacing.
I seriously recommend contacting Dean @ Enduro Gearbox Centre. 011 908 1888 He only works on MB gearboxes and has seen many G owners.

 

[johanmaree]

Dankie Allan

 

[Alan]

Please keep us updated.

 

[JJVDMZN]

The oil cooler of the 350's gearbox is separate (not like the older cars integrated into the water radiator) it's likely that there not enough fluid in the box causing the overheating. My suggestion would be to do an oil change service (new oil, filter and gasket incl. draining the torque converter) because the overheated oil is not good, you can get all the parts at Goldwagen. Note that the box takes +/-9 liters of oil, and you have to follow the instrucions on determining the correct level, there's some good youtube vids showing how it's done.

J.J.

 

[JJVDMZN]

BTW, the cooler is behind the bash-plate below the water radiator it could be that there's dirt between the plate and the cooler.

You'll see the grid it the bash-plate allowing the air through.

Something to also check.

J.J.

 

[johanmaree]

Good morning guys

Yes, it seems the problem was located and I will be travelling some kms today to check it out.
The mechanic started to undo the cooling system pipes to remove the radiator for cleaning. This gearbox cools on a side tank fitted to the engine radiator. Upon going down he felt something funny on the bottom reinforced rubber hose that is feeding the gearbox oil. The bash-plate somehow pushes against the pipe and squeezed it halfway (or more?) close. The bash-plate in that area is not bent at all. This must have happened about three months ago when the AC system was overhauled and the pipe then obviously rerouted (erroneously) fractionally casing the bash plate to touch.

We will now check the oil levels too as the gear change is a bit jerky.

Thanks to all for your advice above. It is still helpful for the future and to others.

Ps. I was really frightened that the gearbox failed.

 

[Alan]

As per JJ's post, I would also replace the oil, unless it was not critically hot. Glad you found the problem.
Does that mean the oil cooling was changed between years of manufacture of the 350's?

 

[JJVDMZN]

As per JJ's post, I would also replace the oil, unless it was not critically hot. Glad you found the problem.
Does that mean the oil cooling was changed between years of manufacture of the 350's?

Mine's a 2014 Bluetec and the cooler is not in the water radiator, I'm also wondering when it changed?

J.J.

 

[johanmaree]

It might have happened when the upgrade to 180kw 600NM happened around 2016. There is also a cooler just under the radiator (as JJ mentioned) but that is for engine oil. I once had it repaired when it chafed against the bash-plate after a rock did some modification down under.

As per JJ's post, I would also replace the oil, unless it was not critically hot. Glad you found the problem.
Does that mean the oil cooling was changed between years of manufacture of the 350's?

 

[JJVDMZN]

It might have happened when the upgrade to 180kw 600NM happened around 2016. There is also a cooler just under the radiator (as JJ mentioned) but that is for engine oil. I once had it repaired when it chafed against the bash-plate after a rock did some modification down under.

Ok, I may have gotten confused with all the oil coolers, One oil cooler in the V of the engine as well, .

J.J.