Problem after thermostat change

[patxi]

I have a 2011 E350 BlueEfficiency Estate and the temp gauge had been reluctant to get up past 80 for around a year but in the last 3 months dropped even less, not getting above 60 unless doing a DPF regen which was around every 500 miles.
I changed the thermostat 2 weeks ago and since then it has been running horribly, it hesitates and is reluctant to pick up speed from low revs. Right after the thermostat change there was an air leak around the turbo inlet which I fixed by taking the air boxes off and carefully reseating everything. At idle there is a slight feeling of air movement to the back left of the turbo (see pic) but I can’t work out exactly where it is from.

When I swapped the thermostat I managed to pinch the green sealing O-ring on the turbo inlet pipe but I put a new one on and that is not the problem.
I’ve now convinced myself that the EGR valve has gone wrong! My theory is that with the engine previously not getting to temp the EGR was sat there doing nothing except get clogged up, but now it is being asked to do its thing it is failing. Are they easy to take out and clean on this engine?
Fuel economy is currently rubbish, worse than it was before, and there is a sooty smell after parking. It has done 2 DPF regens only 100-odd miles apart in the last few days.
Any help or pointers of things to check appreciated. There are no DTCs.

 

[malcolm E53 AMG]

Did you fit a new stat supplied by MB?

 

[patxi]

Yes original MB thermostat for an eye watering £150.
When I said above about reseating everything around the air box I mean the large red and smaller seal. They look in good condition but the clamp was not tight.

 

[malcolm E53 AMG]

The stat does talk to the ECU you may have fitted a faulty new one, mine packed up completely at 60k miles and the car ran awfully until it was replaced

 

[patxi]

I assumed the electrical connector on the top if the housing is just a temperature sender. The car now sits at 92C with little variation after warming up. Are you saying it is chatting more to the ECU than just a temp output?
How could I check if it is faulty?

 

[LostKiwi]

Check all your connections for air leaks. The symptoms suggest an air leak somewhere in the boost pipes.

 

[onefortheroad]

The egr can be prised out and cleaned if you think it's an issue.

 

[Uncle Benz]

Are you sure you didn’t pinch the new green o ring when putting the aluminium pipe on? It’s very easy to do

 

[Larkone]

Use some silicon grease when fitting the green o-rings - helps stop pinching them

 

[malcolm E53 AMG]

I assumed the electrical connector on the top if the housing is just a temperature sender. The car now sits at 92C with little variation after warming up. Are you saying it is chatting more to the ECU than just a temp output?
How could I check if it is faulty?

It will need hooking up to STAR to test if the ECU is receiving temp info

 

[patxi]

It will need hooking up to STAR to test if the ECU is receiving temp info

My iCarSoft displays a temp graph of the car heating up and then holding 87 - 92C during driving. That must come from the ECU I'd have thought?

I'm now going down the split hose investigation but I can't hear anything unusual when revving in neutral, maybe it needs load?

I used a small quantity of silicon grease on the green O-ring and the pipe refitted quite smoothly, a bit of a struggle yes, but no huge forces or hammering, just a firm push.

I hope this is just coincidence that it happened right after the stat change, but that's the way with things sometimes.

 

[star]

+1 for green seal, and you have air movement in that area.

 

[patxi]

+1 for green seal, and you have air movement in that area.

Update, took the turbo pipe off again and it turns out the green O-ring was not sealing correctly despite me thinking it was. Reassembled again and this time no detectable air movement, hesitation gone and mpg back roughly to where it was. TBH, I was hoping for improved mpg with the engine heating more quickly and running at the right temp.

Thanks Star Motors, you’ll be seeing the car in about 4 weeks anyway when I book it on for a service, just like the last 4 years.

 

[mioba]

Just out of interest are you sure you fitted the new stat the right way up.

 

[Uncle Benz]

Update, took the turbo pipe off again and it turns out the green O-ring was not sealing correctly despite me thinking it was. Reassembled again and this time no detectable air movement, hesitation gone and mpg back roughly to where it was. TBH, I was hoping for improved mpg with the engine heating more quickly and running at the right temp.

Thanks Star Motors, you’ll be seeing the car in about 4 weeks anyway when I book it on for a service, just like the last 4 years.

you are very welcome.