09 e350 cdi coupe - Max fan and inconsistent loss of power

[jonnyg]

Im hope I can get some advice.

Firstly my car, I have a 2009 E350 cdi coupe that has covered approx 80k

I recently had to have the turbo silencer replaced and the aux belt and some seals as the bolts had come loose on the turbo silencer box and it was slightly eaten away by a pulley and meant it wouldnt build boost.

All was good until.

I had driven about 15 miles / 20 mins. I could hear a noise and I worked out it was the radiator fan on max. It sounded like a roadsweeper

I then had one instance after about 20 miles where I had a loss of power, I switched to sport and manual and still the same. Kept hitting the kickdown and boom power came back and stayed until I got behind some lethargic traffic and was driving steady behind them.

I have no loss of power once the engine warms up and before the fan goes max.

When I say loss of power, what I mean is I can get max revs, the car does accelerate but not as ballistic as normal. It only seems to be intermittent, If I keep driving progressively the problem doesnt seem to appear.

With regards to the max fan, It doesnt go max if I leave the AC and heating system turned off!!. If I drive and get the fan to go to max, if i turn off the AC and heating system, the fan does go back to normal.

So I took my car back to the indy garage, they tested all the thermostats and controllers and said everything works as expected. They tested the fan and speeds and say that is working fine. No other faults on the car apart from one failed glow plug.

Their advice is to try and replace the front radiator fan as the turbo silencer may have slightly touched it but there is no visible physical damage to the fan and it seems to spin fine.

Im not into replacing the fan as Im not convinced that is at fault.

Does anyone have any suggestions (Thanks for your patience for reading all of this!!!)

Kind Regards,

Jon

 

[cheddar]

Could it be trying to re-generate the DPF? having a large boost leak recently could of caused very high soot loadings onto the DPF?

 

[jonnyg]

Interesting. The engine was cleaned due to crap that got kicked out into the engine bay.

How would I know if its trying to re-generate te DPF? Peesumably these are common things. If I drove like this for a week would that usually mean this would then go away?

I do have one glow plug out but I do 24 miles each way at 40-60 mph and give it a good blast every now and again.

Just FYI - I get no black smoke at all out of the exhaust.

 

[cheddar]

The DPF is in the exhaust and traps any soot/smoke, and is re-generated (cleaned/emptied) by the engine control unit frequently, usually every tank of fuel. It’s normally unnoticeable when driving, the engine control unit adjust fuel timing etc to increase exhaust temperatures to above 600 degrees, it lasts about 15 minutes usually but only starts once the engine has warmed up. Your car might not have one of these anyway but likely does.
Regardless, it may be something completely different.
If it persists, I would get it looked at by a Mercedes specialist if your normal garage cant help.
But I would definitely get the glow plugs changed.

 

[richard]

Also, the fan will run on full if the engine management system can't talk to the air-con module (control panel)

Richard

 

[jonnyg]

Thanks for all the replies

The work I had done was by a MB specialist and when I took it back they said that they have checked everything they can and everything is functioning. Im wondering if the carbon that got kicked out over the engine bay actually got into the fan bearings and has worn them. I would expect them to wear quickly with that sort of grinding paste.

I had no issues this morning with loss of power but will monitor.

 

[jonnyg]

A bit more info for you all from today.

I wen for a longer drive and the loss of power got worse the longer I drove point where I was going uphill (not strep) and car struggled to maintain speed. Then I saw the engine temperature spike to nearly max.

I’m when I got engine temp down some power cane back and max dan stopped

I then did a journey with no ac or blowers on and had no problems, no high temps, no loss of power, no max fan

Definitely not the dpf.

Any ideas?

Could this be a thermostat problem?

 

[cheddar]

It could be, can’t see how having the AC on or off should make any difference. Would even expect it to cool better as the AC will bring the fan on.
If it’s not expensive get it changed, got to be worth a try if you can’t replicate the fault when at the garage

 

[jonnyg]

Its all been very strange but by and large its sorted. I managed to demonstrate the issue when I went.

Coolant Temp Sensor was giving some bad readings. The garage swapped that and it improved things but its not fully sorted.

They then did a test from cold and monitored the signals of the thermostat and the heater element on the top.

They also monitored all temps, fans etc whilst driving and warming up.

Diagnosis was a faulty thermostat. This has been replaced and now full power. The fan now works at 40% rather than 80% too.

Although its got to go back as there must be an airlock in the coolant thats preventing the heat from getting to my blowers. back we go again!

 

[jonnyg]

Airlock sorted and loss of power, high fan and high temps back.

I’m soooo annoyed and upset. It’s going back to the garage but I have zero confidence in them.

What would others do? Give the garage another chance or go elsewhere and then bill the garage.

 

[cheddar]

Might be time to try somewhere else

 

[jonnyg]

Might be time to try somewhere else

I think you are right but they have just had good money from me replaced two bits and in reality I’ve got the same thing back

I’m going to take it back. I’ve told them here is no more money going in from me. I’m going to ask them to go back and recheck all original work as the high fan and loss of power and higher temps started after the work they did.

If they can’t sort then I’m either off to merc and will bill back to the original garage for any work they find wrong.

I’m at the end of my tether with it. I’m half tempted to chop it in and get something else

 

[jonnyg]

I just realised that I hadnt reported back.

The car seems to be fixed. After the third time of bleeding the coolant system the car now seems OK. Apparantly my car was different to other mercs the "specialist" had done, hasten to say I wont be going back.

Im still not convinced that a new thermostat was needed but we will never know now.