malcolm233391

I just bought an 05' E320, certified preowned for 1 year a week ago. Today I've noticed that the hood is hot even after 3 hours of it being off. I popped the hood and touched the engine, and noticed its not really cooling off. So my question is, what could be causing this.

Dtv211

What color is your car, and was it a hot day today? Also, do you have this problem everyday after driving your car, or was it just today?

malcolm233391

Its black, highs of about 90ish today in Sac. I havn't really noticed till today. Got home from dinner at around 8pm, parked it in the garage. At 11 pm, i went out to check on the beauty and noticed the engine and surrounding parts were really hot. Can it be an electrical thing?

Vik888

If its running too hot when driving, the engine temp will get too hot. If its not too hot while driving, it definitely cannot be too hot while its shut off. Once its off, coolant isn't flowing (AFAIK, I'm not a mechanic) so cooling will be gradual. It is a pretty big block of metal under a hood (nothing to prevent the heat from escaping).

Clinton Horn

While I have no way of knowing, I suspect the heat you feel is radiant from the black hood. There is not enough electrical power in the system to make any significant heat over time. Black VS White / Silver is a huge difference in temp. Just ask anyone in a hot climate.
I live in the south and the winters here are fairly mild. I have two vehicles parked side by side in an enclosed insulated garage. The Maxima Silver (3.5L) and the Mercedes Black (3.2L) both operate at about 195 degrees when warm. The Maxima will keep the garage warmer much longer than the M-B. Not a very scientific observation but since heat translates into energy, I would have to say that the M-B is a more efficient vehicle. The Max has never exceeded 28 MPG and the M-B frequently gets 30+. The Max has about a 35 h.p. advantage but it is lighter. It also rolls easier by hand out of the garage. I doubt that this is earth shattering news but I thought it was interesting.

petrolhead

They are designed that way to meet the ever more stringent european emissions rules, less cold starts means better emmissions and economy and less wear. All the insulation material in the engine bay isnt just to keep the noise down. You might find it cools down much quicker if you use the residual heating function.

doxland

With 2005 CDI and previous 1987 300 D Turbo I noticed that both hold their heat for a long time. I've always thought of this as a major benefit. I give the encapsulation credit and the coolant flow pattern credit. I believe that MB came up with an antisyphon pattern for that reason way back around 1974.
Every cold start means more fuel consumption and wear. A warm start, the reverse.
Got a 2004 Dodge truck with Cummins and it'll drop from 90C to 40C in 30 minutes; quite a difference.