benzlover59

Looking at a 2012 S350 Blutec. 67,000 mi. Carfax shows engine/power train/ module checked and steering checked.

Also said drivability/performance checked as well as
wheels speed sensor checked. Seems concerning to me. All maintenance records have been done. Original owner was a lease, was at one point sold at auction. Of course I realize diesels aren’t for everyone so I can understand the auction sale to a degree, but it is a little worrisome. I have virtually the same engine in my 2012 E 350 Bluetec and it has been trouble free with 51000 on it. Any thoughts or advice prior to the upgrade would be greatly appreciated. Thx

JDowney

Hi,

Everything should be OK, just make sure the are no Oil Leaks. You must have the purple oil gasket on your engine...

Jeff

benzlover59

Thank you very much Jeff. The purple oil gasket threw me. This is my first S, where would that be located? Are you talking about oil filter? Thx again

benzlover59

Sorry reread your post, it’s an oil gasket but is it obvious where it is? I’m gonna google it. Never hurts to learn something, even if it is late.

apl175

Oil cooler seals is what is being referred to. The oil cooler sits in the "V" of the engine - unfortunately you can't check it visually without pulling all the bits off (after which you might as well change the seals anyway). I'm going to speculate that by 2012, all of the OM642 engines had the purple seals. You can google or youtube search for OM642 oil cooler seals - to see what is being referred to.

Are you buying it sight unseen? The only gripes I have with my 2013 S350 BT is the rather uneven off the line transmission feeling caused by the stop-neutral feature. When at a stop, the transmission will shift in to neutral. It's supposed to un-noticeably shift in to a drive gear as soon as you pull away - but in my case - you can always feel it.

JDowney

Hi

To fix the oilleak, they essentially have to take the top half of the engine off to get at the gasket; in other words the Turbo Charger portion the engine. Then you have the oil cooler exposed, and can replace the bad orange gasket with the good purple one. The purple gasket is around $50, but it is a Herculean effort to get at it. That alone will be about $2,500-4000 depending on the dealership. Then you get yourself in the situation where if you already have the engine apart, what else should you replace... That could lead into several $$$ more.

Jeff

PS: The sad part here is that this could have been fixed under warranty if it was discovered in time, before the warranty ran out. I also have a ML350 diesel, and it was discovered and fixed under warranty...

benzlover59

Thx for the reply. I just returned from picking it up. Test drove for a good 20 minutes, checked under the car before and after it sat while paperwork was completed no leaks. So happy about that. What did concern me more so was during the test drive all was well but after I filled it up for the drive home the
check engine light came on. Called the dealer think the worse. He told me if it was severe the message warning would pop up telling me what was wrong. I was able to drive the 400 miles home with no issues so I hope it is something like a bad sensor. I did scroll through the messages and “belt adjustment”popped up. I will get it scoped in the next couple days to see what it is. Any thoughts on this would be greatly appreciated. Thanks

apl175

I can only speak from experience....the following issues cause a check engine, but without noticeable power reduction or limp home mode in the powertrain: bad glow plug controller, glow plug(s), ad-blue system heater problem (the latter of which is almost a guaranteed failure before 100k miles). Other things like air-induction leaks, actuators gone bad, EGR issues, ad-blue injection, transmission problems, and some but not all sensors will cause noticeable power limiting along with check engine.

Good luck!!!

benzlover59

Thanks for all that... I guess. It only has 67000 miles on it though so I’m hoping it’s not to severe. The good thing is it’s not my daily driver so I’m not dependent on it.

JDowney

Hi,

Another common problem with diesel engines is the NOX sensor. The S350 has two of them, one on each exhaust system. The NOX sensor wears out every 3-4 years or so. Expensive part (around $500-700) and about an hour to install.

Jeff

PS: Other than the oil gasket and NOX sensors, the S350 is really a great car. Mine has been perfect otherwise...

benzlover59

Oh thx man that’s quite reassuring. I can live with that.

benzlover59

Thanks again Jeff, turns out the NOX sensors were in fact bad and both had to be replaced. Check engine light has been cleared now here is the big question. The mechanic told me that once the computers have been cleared and rebooted so to speak, the car must run for some time to make sure the everything is working properly before it will be able to return data in order to test for emissions to pass the smog test. Does that sound reasonable? They drove it some 50 miles to no avail and said it may take longer driving it to get it to clear in order to read everything. So I drove it 100 miles today and will take it to them Monday to check it again. Did you have this issue or am I getting hosed by incompetency? TIA

Kent

JDowney

Hi,

That s total BS... Once the NOX sensors are replaced properly, the check engine light codes are immediately cleared; otherwise, they were not installed properly. The NOX sensors will last about 3 or more years, but they are consumable parts like brakes, batteries, tires, wipers etc... The good news is diesel engines last forever, the fuel is cheaper, and you get great mileage...

Jeff