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As to not hijack BMW's E350 thread, I am moving the discussion here, below :
My axle part number is A203 351 07 , all measurement based on this unit. This is a common DIFF.
My DIFF drain plug.
I think it is M24. The 1.5mm pitch I am not sure, but seems so.
Drain plug recessed allen "female nut" is M14.
The drain plug itself ( mine ) very likely a M24 size as simulated below.
Drain plug external dimension is bigger than 22.37mm, which 22.37mm is the size of the M14 allan tool shiny socket.
Simulating a 24mm diameter
How my drain plug sits inside the axle/DIFF housing.
My axle/DIFF part number is A203 351 07 , all above measurement based on this unit.
View from the left side ( FILL PLUG ) when pointing to the sky
I am experimenting soon.
I am buying SAMARIUM COBALT magnet, which is known to withstand heat easy 200 Celcius continuos. This is the only high heat magnet I can find locally online.
20mm round diameter, 5mm thick. US$7.00 only. Assuming this is the low end /low power Samarium. https://www.tokopedia.com/wiesena/ma...d20x5mm?whid=0
I will glue this to a metal using JB Weld epoxy and do heat exposure test while submerged in oil , and NOT inside the DIFF for sure https://www.jbweld.com/faqs#:~:text=...0(10%20minutes).
If it is successful, I can even use the 20mm magnet on the FILL PLUG too.
This is a typical sloshing of the oil in an axle and how hot a loaded DIFF on a truck can be :
I so happened been trying to log my DIFF oil temperature and I finally did. 40 minutes ride and 72C skin temperature ...DAMN !!!
However, I can only log its metal skin temperature and I have to add 10 Celcius to the thermocouple reading to represent real oil temperature.
It is very thick metal the DIFF, so heat travel out slower.
Unlike transmission oil pan which is so thin and 5C temperature difference can be expected at car velocity up to 100 KM/H. Faster velocity may cool thermocouple by wind/moving-air alone.
Below at 27.5 minutes.
Thermocouple location. DIFF, K type thermocouple wire I crimped to a round terminal so that I can squeeze it using DIFF own bolts.
At Transmission oil pan. Bare/naked K thermoucouple wire end, sticked to oil pan using 3M aluminium tape. The alu tape itself can assist in heat transfer from oil pan skin to thermocouple.
Pressure pad, DIY, to make sure thermocouple wire end "kiss" properly the oil pan skin
Extra ALU tape sealing for less wind into thermocouple sensing area.
Since I am a bit skeptical with glues in high temperature, and the risk involved, I wonder if those magnets can be drilled through. Drilling the plug, thread it, and use a proper flat head screw (torx to be MB compatible ). Perhaps "loctite it" as well.
The question that comes to mind for me is, why didn't MB powertrain engineers not include a magnet in the rear diff? It's not like magnets are foreign to them. They have been putting magnets in their tranny pans for a very long time. So why not the rear diff?
The question that comes to mind for me is, why didn't MB powertrain engineers not include a magnet in the rear diff?
It's not like magnets are foreign to them. They have been putting magnets in their tranny pans for a very long time. So why not the rear diff?
One is left wondering because mag plugs for big rigs really cost peanuts: $3.
commodity pricing...
This particular model does not look tapered 🤣
Last edited by CaliBenzDriver; Jul 9, 2021 at 11:46 PM.
The question that comes to mind for me is, why didn't MB powertrain engineers not include a magnet in the rear diff? It's not like magnets are foreign to them. They have been putting magnets in their tranny pans for a very long time. So why not the rear diff?
The non LSD DIFF to MB is sealed for life. The life of our car warranty that is
AA. There is no oil change info in my user manual for rear DIFF, only LSD ones from AMG has oil change interval.
Auto trans has fine fluid gallery and the solenoid has fine wire mesh. They need very clean trans oil.
Basically it is a hydraulic system , so clean oil is a must....it has a filter too.
BB. DIFF is crude as in so big gears in them.
Perhaps those AA + BB are the reasons MB doesn't want to use magnetic plug.
In fact the engine oil drain plug is not magnet type.
Since I am a bit skeptical with glues in high temperature, and the risk involved, I wonder if those magnets can be drilled through. Drilling the plug, thread it, and use a proper flat head screw (torx to be MB compatible ). Perhaps "loctite it" as well.
Can not be drilled. It is so brittle when formed.
I got the SAMARIUM COBALT magnet yesterday and I dropped it from a 3 feet table to the ceramic floor, it broke hahahaha.
I got a used magnetic type oil drain plug from my cousin. Came from some Japanese car.
Its seems to be ferrite type magnet. It has zero magnetism already. Must be non high heat magnet.
Yes, the glue-ing part I do worry.
But I want to experiment with oil pan in my kitchen hahahaha. I am curious on how good a JB Weld epoxy can hold the magnet to a steel bolt. I will use the hex end of this drain plug and stick the samarium cobalt magnet there.
Looking at the sloshing power of the oil inside the diff, the magnet choosen from a purchased ready to use magnetic drain plug must be either a high heat Neo 150C or better or this samarium cobalt.
If it is a weak type magnet, I worry any metallic dirt can be kicked back into circulation.
This 5mm thick samarium cobalt is impressive for its magnetic power. So similar to my Neo type.
This is going to be a terrific improvement... compared to what Benz thought was the best: a dumb plug.
Guys with a 4Matic should add one up front if brass is not in question.
Do you think engine sludge would benefit also or does it already have a "magnet in pan" like the tranny?
I never opened my engine oil pan. I wonder if it has magnets like the tranny one.
Looking at fine sludge like thingy on trans oil pan magnet, I think a strong magnet can be good for engine oil pan drain plug too.
Damn damn...
I was about to make a custom Drain and Fill plug for the DIFF with strongest and safest (by installation ) magnet I can find...... I got them, but UK seller does not sell outside Europe. Errgggggg
Today I did about 100KM test run for DIFF temperature, 1 hour 35 minutes of which -12 minutes for warm up and slow speed.
The temp rise is always at the stop and go driving. Acceleration and slow wind speed = HOT.
At highway speed 90-110 KMH wind does keep DIFF cooler.
Constant 90-100 KM/H since minute 12th I joined the highway, to 1hr 26th minute
A bit of extra speed and quick acceleration, oil heat has not transfer out to DIFF casing yet.
Oil heat start to spread to DIFF casing
Simply moving too slow at U turn,add acceleration + braking = 77.3C and expected oil temperature probably 87C.
Ambient temperature 30C when test started at approx 3:30 PM, it was raining 2 hours previous to test, so tarmac is cool. DIFF about 2C cooler over all at highway for same running minutes compared to 7th July test.
I think to get decent cooling on DIFF by moving air, minimum 80 KMH/H is to be achieved, otherwise heat build up may increase a lot if driving profile is stop and go with max speed <50 KM/H, which describe
Jakarta in normal non-highway roads and not at peak traffic.
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). Perhaps "loctite it" as well.
