420 cdi engines - common issues ?

[Lenny63]

Hi

I've been looking at ML420 cdi's and looking fro some guidance on common issues with the engine only

- most examples are now around 130k-150k for the price bracket I have so what would I be looking out for?

Do these also have the oil cooler leak issues that the v6 have ?

Thanks in advance

Lenny

 

[AndrewOl]

I have a GL420 with a 175k miles on it. Change the oil and filters myself with genuine mb stuff. In 30k miles I have only ever put 1.5l of top up in. Amazing for such a big v8 with 12l oil capacity! Plenty of other things have gone wrong with it but the engine has been fine so far.

 

[Lenny63]

Thanks @AndrewOl !! Thats reassuring

 

[merc85]

Great Machines i reckon, Its a itch id love to scratch, I reckon my perfect car would be a e420 cdi 7 seater estate, Shame they never made one

 

[AndrewOl]

The GL and ML are essentially the same. Gearbox TCU is common failure north of 100k. Air suspension too. Rear is cheaper to fix. I used cheap shocks and aerosus bags. Been fine. Fronts are much more complex and expensive. I won’t by really cheap here. Main costs have been with electrical problems. You will need the support of a good Indy garage.

 

[Jobsworth]

Other than the engine, they are same any other w164 ml. Transfer box chains stretch with torque, and the v8 makes a lot of that. Easy fix though, so don’t panic. Listen for a machine gun sound when you hoof it from standstill. You won’t miss it!
Engines are good. EGR valves are common and expensive. There are two. I’ve seen a couple with very heavy engine knock from cold which disappears when warm. Its either little ends or main bearing wear. I’ve never investigated further, but listen for that.

 

[E55BOF]

Speak to the pros, and they'll tell you that if not well-used, the OM629 is prone to sludging up the inlet tracts. This costs an armannaleg in labour to fix, because space under the bonnet is tight, so the lump has to come out to be fixed. That's the main cause for concern, so paradoxically, a higher-mileage example for a given age is probably a better bet, not least because it may have already had the problem occur and been fixed.

Mine will be for sale very shortly. PM me if you're interested...