Just how risky the W166 ML350 Bluetec diesel is?

[RockDriver]

I'm considering the W166 ML350 Bluetec diesel. From what I read so far though it has a few problems. Oil cooler, DPF/adblue, something to do with electronics occasionally grounding the car, etc.

Complication is that in one week I'd have to drive it across continental Europe. Is buying this model now too much of a risk? If say I found one with reasonable mileage, full service history and warranty from the dealer?

My main question is what's the worst possible scenario? Is it the oil cooler and if so, what's the average fix cost estimate (I'm in UK if that matters) at say some reputable MB indy instead of the dealership rip off? Also, is it an acute situation that instantly grounds the car or is it something that develops symptoms over time? I saw somewhere an estimate of around $2K at MB indy (in USA) - it's still a lot, but it's something I could live with if it came to that.

Also, any other insight you could give me on this particular model is appreciated.

 

[malcolm E53 AMG]

I’m not a specialist on the ML but as far as the engine is concerned if you take the engine/gearbox under panels off you can see whether the oil cooler seals are leaking, engine oil will find it’s way down the back of the engine where the gearbox mates if there isn’t any sign of a leak all is well. The seals leak gradually and fill the engine vee with oil and get worse over a long period, the newer viton seals fitted to your purchase are a lot less likely to leak.
Regarding the ADBLUE I wouldn’t worry too much it’s generally low mileage cars that suffer crystallisation of the urea due to lack of use so not an issue as far as your intended use is concerned.
The OM642 has been in production since 2006 and is a well regarded reliable engine

 

[EmilysDad]

(touching wood)
My ML350 is a 14 plate with just shy of 72000 miles & I've not had any problems with either ....

 

[DSK]

A full dealer history = shag knacker. 10/20k fluid changes, give the filters and plugs a change once in blue moon …. Absolutely disgusting. Best to find a genuine low miler that one can save and maintain properly or one that’s been serviced over and above so called be dealer intervals.

Adblue may not be that big of a pain. My w221 bluetec doesn’t get used much and despite being a 2011 is now on a genuine 55k. I have been fine since using an anti crystallisation additive (touch wood).


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[RockDriver]

I’m not a specialist on the ML but as far as the engine is concerned if you take the engine/gearbox under panels off you can see whether the oil cooler seals are leaking, engine oil will find it’s way down the back of the engine where the gearbox mates if there isn’t any sign of a leak all is well. The seals leak gradually and fill the engine vee with oil and get worse over a long period, the newer viton seals fitted to your purchase are a lot less likely to leak.
Regarding the ADBLUE I wouldn’t worry too much it’s generally low mileage cars that suffer crystallisation of the urea due to lack of use so not an issue as far as your intended use is concerned.
The OM642 has been in production since 2006 and is a well regarded reliable engine

Yeah, from what research I've done so far it appears that general consensus is that OM642 is a good engine, just all that stuff that's "appended" to it if you will, like oil cooler and all that DPF, adblue crap that's causing most issues. For me the two most immediate questions of course are what's the most expensive thing that can typically fail and how likely a critical failure is on a longer journey (1300 miles one way in my case). I've been exploring the whole breakdown warranty-insurance angle, but it seems this particular market is full of borderline scams and frustrated customers.

 

[RockDriver]

A full dealer history = shag knacker. 10/20k fluid changes, give the filters and plugs a change once in blue moon …. Absolutely disgusting. Best to find a genuine low miler that one can save and maintain properly or one that’s been serviced over and above so called be dealer intervals.

Adblue may not be that big of a pain. My w221 bluetec doesn’t get used much and despite being a 2011 is now on a genuine 55k. I have been fine since using an anti crystallisation additive (touch wood).


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The lowest mileage I could find in my price range is 80K miles. There are a few options around 100K miles. Is that good enough? From what I understand diesels in general will have higher mileage compared to petrols, because longer trips are where they shine. Also the whole thing in general about city miles being much more taxing on a car than motorway miles.

 

[malcolm E53 AMG]

MB franchises offer the best breakdown warranty for a year after purchase so well worth considering buying from them they tend to have the pick of the S/H market anyway, it would certainly be my first port of call. You would be very unlucky to encounter problems with such a new engine unless the car has done high miles so I wouldn’t be overly concerned as I said earlier if the OM642 has a full service history they are very reliable

 

[RockDriver]

MB franchises offer the best breakdown warranty for a year after purchase so well worth considering buying from them they tend to have the pick of the S/H market anyway, it would certainly be my first port of call. You would be very unlucky to encounter problems with such a new engine unless the car has done high miles so I wouldn’t be overly concerned as I said earlier if the OM642 has a full service history they are very reliable

Do you mean the MB "approved used" search on their official website? Because if so, there are no MLs there, only GLEs and they start at around 30K, quite a bit more than what I'm looking for right now.

Also, what would you say is high miles for this particular model?

 

[malcolm E53 AMG]

I’d be inclined to look for something <60k miles. Yes, I did mean ‘approved used’ but I guess that model is too old for their forecourts now but they do occasionally list the odd older model for sale if it’s a low mileage known history example.

 

[malcolm E53 AMG]

What’s your budget if you don’t mind me asking? Or you link one or two cars you are looking at for comment

 

[RockDriver]

I’d be inclined to look for something <60k miles. Yes, I did mean ‘approved used’ but I guess that model is too old for their forecourts now but they do occasionally list the odd older model for sale if it’s a low mileage known history example.

I see. Well, options with low mileage like that start at around 20K which is around 6-7K more than 100K cars. The way I see it, if within a couple of years or so I spend less than those 6-7K in potential repairs, the higher mileage car is still worth consideration. I don't suppose there's some average annual repair stats lying around somewhere?

Also, if I was gonna shell out 20K right now, I'd probably be looking for a 3rd gen X5 instead, because what bothers me about the W166 is that they are so miserably low specced. Xenon headlights, electric folding mirrors and so on are nowhere to be found and all that partial leather crap (no offense to the MB fans by the way, I've had 3 in the past myself so far).

 

[RockDriver]

What’s your budget if you don’t mind me asking? Or you link one or two cars you are looking at for comment

Well, there's this one for instance: https://www.autotrader.co.uk/car-details/202209089555625
The others in the same price range are unfortunately around 100K miles. I mean, mileage is a good parameter, but not always reflect the state of the car. Just recently we were looking for an X5 E70 for my friend and we went to see one under 60K mileage which looked mint in pictures, but was beat to hell in person - literally chunks of plastic missing from the cabin, loose steering wheel and drove like a ticking time bomb.

 

[malcolm E53 AMG]

We get very few problems reported on here regarding newer ML models so the 350cdi would be my pick

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EU5 without ADBLUE

 

[malcolm E53 AMG]

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[RockDriver]

We get very few problems reported on here regarding newer ML models so the 350cdi would be my pick

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EU5 without ADBLUE

Yeah, I actually forgot to mention that ULEZ is a hard requirement for me. In all honesty I was already looking at the W164 V8 petrol as I've had W163 V8 petrol in the past with fond memories, but I figured if I'm gonna shell out 10 grand for a 16 year old car, I may as well add a couple of grand and get the newer gen one. And just to clarify I don't have preference for either petrol or diesel as long as the car drives well and doesn't break just by looking at it.

Also I've read that W164 tends to rust quite a bit compared to other models.

 

[sonic]

Yeah, I actually forgot to mention that ULEZ is a hard requirement for me. In all honesty I was already looking at the W164 V8 petrol as I've had W163 V8 petrol in the past with fond memories, but I figured if I'm gonna shell out 10 grand for a 16 year old car, I may as well add a couple of grand and get the newer gen one. And just to clarify I don't have preference for either petrol or diesel as long as the car drives well and doesn't break just by looking at it.

Also I've read that W164 tends to rust quite a bit compared to other models.

If ULEZ is a requirement for you you need a Euro6 diesel with addblue, I think they came in about 2015. Otherwise its petrol.

 

[DSK]

To be honest I should have said low owner and maintained over and above dealer intervals regardless of miles.

The 2011 S350 bluetec is eu6 so just check on the ML as some models will be eu6 before others. IIRC the E class became eu6 around 2015 with the same hardware.


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[RockDriver]

If ULEZ is a requirement for you you need a Euro6 diesel with addblue, I think they came in about 2015. Otherwise its petrol.

Actually, W166 ML350 Bluetec (starting from 2012) is Euro 6, so ULEZ compliant. Checked a couple of plates on TFL website just in case.

 

[RockDriver]

To be honest I should have said low owner and maintained over and above dealer intervals regardless of miles.

The 2011 S350 bluetec is eu6 so just check on the ML as some models will be eu6 before others. IIRC the E class became eu6 around 2015 with the same hardware.


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The very first 2012 W166 ML350 Bluetec is definitely Euro 6 and ULEZ, checked and double checked on the TFL website to be sure.

 

[RockDriver]

as far as the engine is concerned if you take the engine/gearbox under panels off you can see whether the oil cooler seals are leaking, engine oil will find it’s way down the back of the engine where the gearbox mates if there isn’t any sign of a leak all is well.

I assume it's possible to see that from underneath the car? The reason I'm asking is because I have fashioned myself a live inspection camera on a selfie stick connected to phone that I have used a few times to check for oil leaks.