2012 E250

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Reddle28

New Member
Joined
Mar 15, 2023
Messages
7
Location
Ireland
Car
2012 E250
Hi Folks,
First post and first Merc. Just bought a 2012 E250 Sport two weeks ago. I bought it privately so unfortunately no come back with any issues of which i have noticed there is a few. Im hoping some of you can help. It has 119k miles, full documented service history and in general in very good condition but there's a few small concerns:
- Engine oil leak - theres a minor oil leak that would only be notices with the engine oil pan/guard removed - left running for 10 minutes equals two to three small drops - seems to be coming from the front of the engine but i just cant see where exactly - the oil cooler looks dry, filter housing fine too - any help welcome?
- Idle is a little lumpy when cold, stable but blips up 30 or 40 rpm every 10 seconds or so (idle is about 830rpm) - its very noticeable stopped in traffic - feels like a minor fuelling issue. Fuel filter is just done in recent service and no engine error codes from my diagnostics (basic Launch reader) - one point to note, when looking at the data on the diagnostics the fuel rail pressure looks erratic to me but this might be normal, swings from 25000kpa to 35000kps (see image attached) - this may of may not be related - any help welcome?
- Lastly, im not familiar with these engines but at idle it vibrates a bit, not massively though, hard to explain in text but in park or neutral it feels relative normal however as a comparison the wife has a 2.2 diesel Santa Fe that has definately less vibration in neutral, however, once its put in D or R the vibration significantly increases to a level that i feel could not be normal - had a look at the engine and gearbox mounts and they dont look obviously bad but hard to tell. I have heard torque convertor could cause this but im not so sure - any help welcome?

In general, the car runs well in terms of power, no slippage in the gears, gearbox seems to change very smoothly, lovely smooth car to drive especially on motorways. Not sure how i missed the above issues when buying it, the oil leak aside which i just couldnt see until removing the cover the other two issues didnt seem to be there the day i bought it but maybe they were and i was just to eager to buy it, anyway sorry for such a long post, looking forward to some replies!

Ill keep this thread updated with my progress as i go.

Regards,
Red.
 

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The vibrating engine I would say could well be engine mounts +/- transmission mount. Mine was transformed when I changed them at about 90k miles. Mine also looked fine but evidently they were shot. I think they’re oil filled. Not too expensive to change and really improved the gear change as well. If it’s any indication for yours I could also feel some vibration on the transmission tunnel inside the car. Sorry I can’t help with the other issues!
 
The vibrating engine I would say could well be engine mounts +/- transmission mount. Mine was transformed when I changed them at about 90k miles. Mine also looked fine but evidently they were shot. I think they’re oil filled. Not too expensive to change and really improved the gear change as well. If it’s any indication for yours I could also feel some vibration on the transmission tunnel inside the car. Sorry I can’t help with the other issues!
Hi Chris,
Thanks for the reply, i really appreciate it, yes i think they are oil filled, on the engine ones anyway, i am considering changing them altogether, im relatively confident in checking the condition of traditional engine mounts but not these ones so i might just do them, about €150 per engine mount here for Lemforder ones and €50 for the tranny one, straight forward to change too so i think ill give them a go in the next few weeks.

Regards,
Red.
 
Hi Chris,
Thanks for the reply, i really appreciate it, yes i think they are oil filled, on the engine ones anyway, i am considering changing them altogether, im relatively confident in checking the condition of traditional engine mounts but not these ones so i might just do them, about €150 per engine mount here for Lemforder ones and €50 for the tranny one, straight forward to change too so i think ill give them a go in the next few weeks.

Regards,
Red.
Autodoc can offer good rates on parts so may be worth a try. If you use the app I think you get more discount.
 
I have a C class C250 with the same om651 engine, mines on 120K. I also get some vibration at idle when in drive, I also notice it when slowing to a stop. Kind of a grumble briefly. I suspect the engine mounts are on there way out but haven't had a proper diagnosis. I did have a courtesy car from the main dealer while my airbag was replaced, it was an A class 220D and to be fair that was worse than mine and it only had 20K miles on it. So for now I will live with it.

As for the engine idle, I would strongly recommend running some diesel system cleaner through it for a few tanks full. At the mirage there will be carbon build up and the stuff can help clear it out. I run mine through every other tank.

They are strong engines but they do need a good run now and again and to be maintained.

The oil leak, I am not sure about. Mine has a minor leak from around the egr pipe but its very very minor.
 
I have a C class C250 with the same om651 engine, mines on 120K. I also get some vibration at idle when in drive, I also notice it when slowing to a stop. Kind of a grumble briefly. I suspect the engine mounts are on there way out but haven't had a proper diagnosis. I did have a courtesy car from the main dealer while my airbag was replaced, it was an A class 220D and to be fair that was worse than mine and it only had 20K miles on it. So for now I will live with it.

As for the engine idle, I would strongly recommend running some diesel system cleaner through it for a few tanks full. At the mirage there will be carbon build up and the stuff can help clear it out. I run mine through every other tank.

They are strong engines but they do need a good run now and again and to be maintained.

The oil leak, I am not sure about. Mine has a minor leak from around the egr pipe but its very very minor.
Hi Tonygw,
Thanks for the reply. Yes the grumble you described sounds similar to my vibration issue. Ive pretty much decided to do the 3 mounts so once done ill let you know if it changes things.
The diesel system cleaner is a great call, thanks, ive never really been a fan of these products as in my experience they never really resolved any issues, however, i used some two days ago and to my surprise i actually think the idle is smoother!! lets see if it resolves it in the long term. While we are on the topic, not sure if you are allowed recommend products on here but if you are, if anyone has a good recommendation for a diesel cleaner please share as there are so many products its hard to choose.
I will check the EGR for any leaking, thanks. Is there a vacuum pump at the front of these engines that could be the cause of the oil leak?

Regards,
Red.
 
Hi Folks,
An update on my issues above;
1) The vibration issue is sorted, changed the 2 engine mounts and the gearbox mount and its like a different car, way smoother, vibration of the engine is hardly noticeable.
2) The oil leak i think is sorted too, changed the rocker cover gasket and im nearly certain that has resolved it but will keep an eye on it for the next few weeks as it was a very minor leak. When the rocker gasket came out the middle section was a little corroded so i think this is where its coming from.
3) Lastly, the rough idle when cold is not fixed, did a full service on oil and filters and changed the fuel filter too which i though might help this but no luck. its minor but it does bother me! its a small blip up in rpm every 5 or 10 seconds and then settles and again and again. Once engine temp is up above about 80 its stops, any ideas on this one?
Thanks,
Red.
 

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