Fluctuating coolant temp

[Mr Filipov]

Hello all, I was wondering if someone can shed some light on this for me please? It is a 2011 E350 CDI 265. When the car is fully warmed up as such the coolant temp seems to fluctuate between 80 and anything up to 90ish. Mercedes are trying to sell me the usual that is normal story, but coming from a CLS320 CDI where the temp got to ~90 and was stable there with no fluctuation, I am not do inclined to buy their story.
Now the heatijg in this one plays a part too. Woth the heating on full on hot blast ofr the sake of experimenting the temp drops even lower to below 80 briefly and slowly goes back up. Last night however I was in the car for close to an hour and it mainly seemed to sit below 80. Heatijg was not on full heat and max blowing etc, it was as I normally have it. I do not run AC and with heating on max heat and high blowing the engine rpms also increase to ~800 at idle as if the car is still warming up.
I suspect it might well be the thermostat, but any recommendations are very welocme.

Thanks in advance.

 

[Oldlae]

Thermostat going west.
Tony

 

[mbenz1]

Hello all, I was wondering if someone can shed some light on this for me please? It is a 2011 E350 CDI 265. When the car is fully warmed up as such the coolant temp seems to fluctuate between 80 and anything up to 90ish. Mercedes are trying to sell me the usual that is normal story, but coming from a CLS320 CDI where the temp got to ~90 and was stable there with no fluctuation, I am not do inclined to buy their story.
Now the heatijg in this one plays a part too. Woth the heating on full on hot blast ofr the sake of experimenting the temp drops even lower to below 80 briefly and slowly goes back up. Last night however I was in the car for close to an hour and it mainly seemed to sit below 80. Heatijg was not on full heat and max blowing etc, it was as I normally have it. I do not run AC and with heating on max heat and high blowing the engine rpms also increase to ~800 at idle as if the car is still warming up.
I suspect it might well be the thermostat, but any recommendations are very welocme.

Thanks in advance.

If it's fluctuating then I'd also put my money on the thermostat. Not a hard job for the average DIYer and you'll need some neat coolant ( genuine) from MB. The part should not be expensive and again only use genuine MB parts. Coolant spec I think is 325.0 for this engine also.

You may also get a slight improvement in fuel economy. Good luck.

Sent from my GT-I9505 using MBClub UK

 

[Mr Filipov]

I thought as much myself. I will see what I can do. Thanks for the heads up everyone.

 

[Mr Filipov]

Sorry to re-surrect this thread. It still seems to be going south (the temp gauge that is). At motorway and a road cruising it has now dropped to around 75c at steady speed. Now all well and good, I can get the whole lot done for about £250-270 with no hanging around. This included a new stat, coolant temp sensor, and enough coolant for a system flush, and of course labour at my local indie, who seems to be more knowledgeable than Mercedes themselves. Mercedes on the other hand want £290 labour and another £168 for the stat. Now to me that seems a bit excessive when my local only quoted an hours labour at £50 + VAT. that is quite a gap and if needs be I can stretch to get it done at Mercedes, however the bit that annoys me is the fact that the car is under used approved warranty, which indeed covers this part, but the cowards just don't want anything to do with it.

Bottom line of the rant is this. Is there a way to make them fix it, so I don't have to be out of pocket?

 

[Yugguy]

Why are they not covering it? If it is specifically mentioned on the list then it should be covered. Is it the dealer refusing or MB themselves?

 

[Mr Filipov]

Left the car with MB last time for then to have a look at. They said it was all normal. Thats MB Bedford to make it clear. When I asked for a report, all I got back was a short and sweet email saying all is fine after a short test. Don't know what the test is, if they have even done one, or just left the car idling at a standstill, which does eventually bring it up to temp. I am at a loss. Don't really want to go near another main dealer because nobody will just have a look at it. They all want full diagnostics charge or nothing to do with it. For a car under their warranty that is unacceptable. My last car had a third party warranty which covered most of the car and could be done by any garage in the country.

Dealers seem very good as selling cars, but when it comes to aftercare, the car is now gone and they do not care.

 

[Ted]

Ask to speak to the service manager and explain it to him/her.
I had exactly the same with my slk when it was under a sales warranty. They diagnosed it as a faulty temperature sensor which I accepted as it is a long time since I worked on cars and what do I know.
Took it back to have the sensor fitted, within a mile it was obvious that it hadn't been fixes, returned and the 'technician' took a look. "It's running at 65" I said. "That's the temperature they run at" he said. "No it f**** isn't" I said. "I'm not f**** stupid". To which he stormed off.
I went back, politely asked for the service manager, showed him what was happening and suggested that it was the stat, as I first suggested. To his credit, he nodded, said that was what it was and ordered a new one to be fitted.
Three bloody visits and a ****** off customer to replace a faulty stat - thirty years previously they would have done it first time while you waited.

 

[grober]

The coolant pump on the OM 651 4 cylinder diesel can be vacuum decoupled/ de-activated to help engine warm up--- not sure if this is the case on the V6 engine or not?
https://www.manualslib.com/manual/1197420/Mercedes-Benz-Om-651.html?page=42

 

[Jonesy161]

Ted, sounds like you are very much like me, 10 years since I worked on cars but still understand the basics, why oh why don't so called specialists get to the bottom of problems straight away rather than bullsh1t you.

 

[Mr Filipov]

I am going to Gertford Merx tomorrow for them to do a dignostics. Not sure on them as has never been, but I believe they have positive feedback. Feel free to correct me if I am wrong. Once that is done and if something is indeed due a change I will be visiting Bedford on my way back with a printout. May well just be myself going crazy, but that is erratic and cannot make its mind up as to where it wants to sit on the gauge. Sometimes it hovers below 80, other above. God forbid you have to use some heat, then 75 it is. Most annoying part is there is no statement set in stone where it says the correct temp that the car should sit at.