Oil leak, left hand side

[E250_MK]

When my car was serviced in Jan they mentioned there was a small oil leak which needed looking at at some point. Because it was minor and because I did not notice any oil drips on my driveway I forgot about it. I took my car into a local MOT place today for an MOT and they failed it due to excessive engine oil leakage. However, they noted that the engine oil level was fine (full). No oil had been added since the service in Jan.

The oil is appearing on the left-hand-side of the engine and appears to be coming from either the engine oil cooler, or the rocker cover. Main dealerships have quoted around £700 for the engine oil cooler to be replaced, and around £300 for the rocker cover gasket to be replaced. Yikes! But the MOT place have quoted £350 to replace the oil cooler with a genuine Mercedes part (the part is only £110, the expensive bit is about 3 or 4 hours' labour).

Does anyone else know what the likely causes of the engine leak might be, and what the costs of repair are? I'm wanting to prepare myself for what bills might be coming!

 

[grahamcol]

I'd be questioning the strictness of the mot here. I've known lots of cars with oil leaks pass with absolutely no mention of an oil leak.

 

[rf065]

I've spilt oil over the engine when filling up after an oil change, next time in Mercedes, they told me I had an oil leak but it was only the oil I'd spilt myself. A good clean was all it needed.

 

[E250_MK]

I'd be questioning the strictness of the mot here. I've known lots of cars with oil leaks pass with absolutely no mention of an oil leak.

Yes I think its a bit strict. They did say that the oil could have been dripping and collecting into the undertray, and that a few big blobs spilled out when they put it on the car lift. Their car lift is a bit uneven, so the car was tilted forward, which they said might have resulted in more of the collected oil spilling over undertray edge. They still failed it, though! They showed me on the floor 3 or 4 small pools of oil, a couple about the size of a 50p piece, and one about twice that size.

I may try cleaning out the undertray then booking another MOT at another MOT centre.

To test the speed of the oil leak, I plan to put white paper down on the drive way, postion the car over it and leave the engine running for 15 minutes.

 

[E250_MK]

I just put white paper down on the drive way, postioned the car over it and left the engine running for 15 minutes. Not a single drip of oil on the paper.

 

[grahamcol]

I bet there's a good chance of passing a new mot if you do mop up as much as possible before taking it in.
Of course, if the leak is pronounced I'd look to get it fixed but if the car isn't needing any top ups it might just need keeping an eye on.
Good luck.

 

[E250_MK]

I left the engine runnning for 40 minutes, and there is a bit of a leak. Probably not enough to fail an MOT, but it definitely needs to be fixed sharpish.

 

[alcmackew]

From my experience (OM651 engine) could be either sump, oil switchover valve or oil cooler. In my case all 3 were replaced which was an engine out job. With the undertray the oil travels along to the exit points on either LHS or RHS depending on the which of these are leaking.

 

[E250_MK]

The MOT garage has said they are 99% certain it is the engine oil cooler, and have quoted £360 (inc VAT, parts & labour) to replace it with a genuine Merc part.
Part is guarantees for 12 months, labour guaranteed for 6 months.

This is a lot cheaper than Mercedes MK dealership's quote of around £600, plus the standard £190 to diagnose the leak (they won't accept the diagnosis of another garage).

How good are MOT-MK? Can anyone vouch for them? Or is this repair best done by a main dealership?

 

[alexanderfoti]

Oil cooler on these is part of the filter housing (comes as all one part) and is not too bad to change. Quite a common place for a leak on these. Get a good independent to do the repair at approx half the cost of main dealer.

 

[E250_MK]

Oil cooler on these is part of the filter housing (comes as all one part) and is not too bad to change. Quite a common place for a leak on these. Get a good independent to do the repair at approx half the cost of main dealer.

That's the challenge, how do I find out if MOT-MK are a good independent? They only guarantee the work for 6 months whereas the main MB dealership guarantee the work for 24 months.

MOT-UK say they will use a genuine MB oil cooler, but I from what I have read it is vital that the correct purple Viton gaskets/seals are used. I'll check with them that they will use these, though I assume the gaskets/seals all come with the unit.

 

[alexanderfoti]

That's the challenge, how do I find out if MOT-MK are a good independent? They only guarantee the work for 6 months whereas the main MB dealership guarantee the work for 24 months.

MOT-UK say they will use a genuine MB oil cooler, but I from what I have read it is vital that the correct purple Viton gaskets/seals are used. I'll check with them that they will use these, though I assume the gaskets/seals all come with the unit.

You are confusing the coolers between the 2.1L and the 3.0L diesel, the 2.1L diesel and the gasket are bought together and have no major issues.

Its a straight forward job. The part will be warranted by MB for 24months, regardless of who fitted it

 

[E250_MK]

You are confusing the coolers between the 2.1L and the 3.0L diesel, the 2.1L diesel and the gasket are bought together and have no major issues.

Its a straight forward job. The part will be warranted by MB for 24months, regardless of who fitted it

Ok, good to know, thank you.

MOT-MK are not a Mercedes specialist, they're a standard gerneral purpose garage. I'm nore worried about the work being garanteed, not the part itself. I imagine a general garage are more likely to make a mistake fitting it than an independent Mercedes specialist or main dealership. I need to decide if its worth paying the extra £350 (and waiting 3 weeks for an available slot) at an MB dealership.

 

[E250_MK]

I took my car into MOT-MK. They had said they were 99% certain replacing the oil cooler would fix the leak), and estimated £360 total. I asked them to call me if they found it wasn't the oil cooler before doing anything else so we can discuss the options.

Before I handed over the keys I asked them to print what we agreed on a job card. Suddenly they went very frosty and refused to do the job.

If they can't put 2 sentences in writing confirming what we'd discussed verbally, then that is a huge red flag.

 

[SL63 Mark]

As above, find a good independent Mercedes specialist near you. If you let us know where you are, we may be able to recommend one.

Sounds like your relationship with MOT-MK is over, whoever they are, time to move on.

 

[E250_MK]

Milton Keynes area. Autoclass are booked out until end of June