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W212 Rusty sump pan (pans!) woes - Oil pan and transmission pan

MrGreedy

MB Enthusiast
Joined
Jan 13, 2020
Messages
2,807
Location
Here and there
Car
E350 CDI
Unluckily for me, from today's inspection at the independent Merc Specialist, both my transmission sump pan and my oil pan are rusty in specific places, with badly breached (missing) paint.
The transmission pan is really rusty around the drain plug hole.
The oil pan is really, really rusty around the oil level sensor hole.

I've had a new transmission pan fitted today as the car was in for an ATF change (last service was 4 years, 20k miles ago).
Original part number A2222700512, now replaced with A9062700501 (£69 for the part only for the specialist to fit, as obviously the old one was off for the fluid change).
Price seems pretty reasonable, as there are a good few used, genuine MB ones in not pristine condition available on eBay for £50 plus shipping. Who would pay that?

The oil pan (part No. A6420102028) is recommended to be replaced next year at the oil change.
Unfortunately, the part looks to be £250-300, judging by genuine Merc new sump pans for sale on eBay.
Double unfortunately is this isn't really an easy DIY, as engine lifting/subframe lowering required to get the pan out.
Because this isn't a DIY, I'm restricted to a new pan because understandably, the specialist won't fit used parts.

I try not to drive through puddles. All undertrays are intact and fitted.
I'm a bit surprised that both of these need changing.
Might be worth a close look if you DIY your car.
Mine is very late 2011, so only 12 years young.
 
Unluckily for me, from today's inspection at the independent Merc Specialist, both my transmission sump pan and my oil pan are rusty in specific places, with badly breached (missing) paint.
The transmission pan is really rusty around the drain plug hole.
The oil pan is really, really rusty around the oil level sensor hole.

I've had a new transmission pan fitted today as the car was in for an ATF change (last service was 4 years, 20k miles ago).
Original part number A2222700512, now replaced with A9062700501 (£69 for the part only for the specialist to fit, as obviously the old one was off for the fluid change).
Price seems pretty reasonable, as there are a good few used, genuine MB ones in not pristine condition available on eBay for £50 plus shipping. Who would pay that?

The oil pan (part No. A6420102028) is recommended to be replaced next year at the oil change.
Unfortunately, the part looks to be £250-300, judging by genuine Merc new sump pans for sale on eBay.
Double unfortunately is this isn't really an easy DIY, as engine lifting/subframe lowering required to get the pan out.
Because this isn't a DIY, I'm restricted to a new pan because understandably, the specialist won't fit used parts.

I try not to drive through puddles. All undertrays are intact and fitted.
I'm a bit surprised that both of these need changing.
Might be worth a close look if you DIY your car.
Mine is very late 2011, so only 12 years young.
Rub the oil pan rust away , treat and repaint , spray with dinitrol afterwards ?
Might bat it into the future for a few years .
 
Rub the oil pan rust away , treat and repaint , spray with dinitrol afterwards ?
Might bat it into the future for a few years .
Yes. I think for the summer oil change, I'll drop the drain plug and remove the level sensor, as I have a feeling that the sensor will need to be removed to allow me to clean up the rust on that bit of the pan properly.
Not the easiest of locations to clean up. But got to be worth a try to save £500!

1736523685072.jpeg
 
I drive through as much clean standing water as possible before the salt season, and after. A bit slower since I ripped an £80 side cover. My reasoning is disturbing and rinsing off as much of the oxide formations as possible 🤣

And wash the engine and gearbox every ~5k miles or so. Mint sumps at least. (167k E320 CDI from 2006 and 140k CLK 240 from 2002)

Losen covers to remove trapped debris as needed.

My CLK 320 CDI has breached the transmission sump, but that's at 220k miles of other owners.
 
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Never heard of anyone washing their engine or gearbox every 5k miles!

And people say running an EV is an inconvenience 🤣
 
Never heard of anyone washing their engine or gearbox every 5k miles!

And people say running an EV is an inconvenience 🤣
My diesel engine bay smells fresher than the inside of the car 😁
 
You need to use Swarfega when you’ve finished!

Ahh, brings back memories! :D
 
I had a 2010 E350 7 speed. The atf/ gearbox service was not too expensive although I cannot remember how much. The gearbox filter was a replaceable part within the box.
I replaced it with a 2015 E350 9 speed. On this gearbox the filter is part of the gearbox sump and the part is eyewateringly expensive.
So my question is, are you sure that the expensive gearbox sump you've found is for your car, presumably 7g?
 
I had a 2010 E350 7 speed. The atf/ gearbox service was not too expensive although I cannot remember how much. The gearbox filter was a replaceable part within the box.
I replaced it with a 2015 E350 9 speed. On this gearbox the filter is part of the gearbox sump and the part is eyewateringly expensive.
So my question is, are you sure that the expensive gearbox sump you've found is for your car, presumably 7g?
Hi Keith,
It's 7G+
Transmission sump pan is just a shave under £70 at present. Not too bad.

It's the engine oil sump pan that's £250 (part only), hence I'll be trying to give it a clean up around that oil temperature sensor, remove and treat corrosion an re-paint in the summer.
If during that work it looks terminal, I'll hopefully be able to wait until Jan 2026 for my independent specialist to change it.
 
Rub the oil pan rust away , treat and repaint , spray with dinitrol afterwards ?
Might bat it into the future for a few years .
What happens is the rust bubbles into quite a large bubble and then it pops and then fluid leaks out at a dramatic rate.
 
Clean the area and apply this ,then overpaint with hammerite , if all else fails , it's new sump time I guess. Screenshot_20250115-141023.png
 
What happens is the rust bubbles into quite a large bubble and then it pops and then fluid leaks out at a dramatic rate.
Do you think the rust indicated by the poor photo in the original post is too far gone?
I'm not too bothered by how long it might take to do a good job, but more about the cost at this point.

Whilst I do usually maintain my cars regardless of cost, it's been an expensive end/beginning to the year with 4x new winter tyres, new radiator and all hoses, new expansion tank, new PAS reservoir, DIY engine and diff oil change, a garage service and MOT (including another engine oil change) with ATF change plus new ATF sump pan, new transmission oil line, rear ride height sensor, air and cabin filters, fuel filter, batwing and all the seals on the air charging pipework. We're talking heading towards £3k even with the bulk of that being DIY.
And with some suspension components and a new engine oil pan on the horizon, it's stretching the pay packet a little right now.
 

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