Yellowing?

[Headhurts]

Firstly I was not sure whether to put this thread under bodywork section but read on first.
My car is a white E300 Hybrid now 6 months old.
I had a recall to have a timing chain tensioner seal replaced and this work was carried out today.
On picking car up I had a good check round the car externally and internally for any damage (previous experience has taught me this.)
On arriving home I lifted the bonnet and checked all is ok and everything looked superb and clean.
As I went to put the bonnet down I noticed a yellow staining of the White paint on the right side near the edge closest to the wipers. (As looking from the front)
Now I am pretty anal about my cars and keep them pristine including under the bonnet and the car was fine on Saturday when I cleaned under the bonnet.
This could be a paint flaw but I doubt it, has anyone any ideas?
I am returning the car tomorrow for the dealership to have a look so any input would be very useful.

 

[television]

Until one has tried to polish it off it is all too hard to comment.

 

[Headhurts]

Polish

Yes I have tried polish but not any cutting compound.
It does not appear to be an overspray of any type as too smooth.
The car was extremely hot when picked up and it had been sitting for 15 mins,
The engine was clicking like the sound of metals cooling but surely the paint should withstand extreme temperatures?

 

[television]

Yes certainly one would think so as there are many countries hotter than the UK,, please let us know what they say.

 

[Headhurts]

http://www.slkworld.com/slk-r172-general-discussion/193273-yellow-mark-under-bonnet.html

This is exactly the same colouring as I have, could the have got the engine so hot in the workshop to have caused this?
I mean in normal use air from outside would be cooling the engine but in a workshop this would not be so I guess, same side as mine also.
As said earlier the engine was ticking as it was cooling down and I have never heard this from my car before.

 

[television]

I wonder if they left it running too long, maybe to do with the DPF, but these are not my line.

 

[Cole@MBS]

Just a thought, its not a oil stain from the said work done today, sometimes using a air blower can spray oil over paintwork??????

 

[Headhurts]

Too hot

Thanks for replies thus far, I suspect that after the work was completed the technician gave it plenty of beans on accelerator to make sure the seal was secure but with no air passing through the car to dissipate the heat this caused the paint to go yellow.
I now have to decide whether to live with it or get them to rectify which may mean bonnet off for an under bonnet re spray.

 

[grahamcol]

I'm pretty amazed that in this day and age we can have a situation where a new car's paint is unable to withstand normal every day use and maintenance. Even if the car has been subjected to increasing temperature during maintenance, surely this should not cause the paint to suffer ? If indeed this has been caused in this manner then surely it's likely to happen again if the area is resprayed. And maybe the respray won't even be as resistant as the original finish. I'd probably (reluctantly) live with it. Not good though !

 

[Rotorhead500]

It shouldn't be caused by heat-soak, especially on a modern car. They're designed, as Malcolm says, to operate in countries far hotter than ours, including spells replicating being sat in traffic for example.

I would get straight back to the dealer - state firmly that the blemish wasn't there on Saturday when you cleaned the car...

 

[television]

Do not forget that these cars are Nano coated, and this ceramic paint is fired on at a very high temp.

 

[L John]

Most likely a smoke stain from oil burning off a hot surface or from a vent.

As long as there's no issue with the engine I'd say it's not a problem.
It should come off very easily with t'cut if it is a smoke mark.

 

[Headhurts]

Update

So I visited the dealership today and the technician who worked on the car came out and I suggested he ran the car at high revs to confirm seal was ok, this he did not deny but said the paintwork should withstand this heat and anyway most of the heat comes from the left side (as looking at car from the front).
The sort of heat my car generated must have been severe as the technician had finished, it had been for a wash and Hoover and when I approached the car it was still clicking as the metals were cooling.
A body shop manager was then called he took the car away to measure the paint thickness etc.
When he returned he told me that he had taken photos to send to Mercedes to get authorisation for repair under warranty.
He did say in his opinion it was something to do with the pigmentation and he had seen this before and it was caused by heat.
He told me the White and Red cars seemed most prone.
I am no expert but I guess the heat generated and trapped under the bonnet must have been extremely high to have affected the paintwork.
The car is around 6 months old so I do not foresee any problems with Mercedes authorising the work unless they consider the dealership is responsible.

 

[Rotorhead500]

I know red suffers greatly from heat/uv degradation, or certainly did until recent years.

Hopefully with his statement, the age of the car and their 12 yr bodywork warranty, they should do the decent thing!