emin.mak

I have 07 S550 and my engine temperature jumps from 80-100 is this normal? Also when it’s closer to 100 it’s making a small knocking noise. MB San Francisco telling me it’s normal. Should I be concern about this?

Your help is much appreciated

Thanks

emilner

I average 90 on these hot summer days...

eugene22n

Doesn't sound normal to me. Maybe take it to another dealer for confirmation?

emin.mak

Checked with another dealer and this seems to be normal.

Thanks

Corsa9000

It is very normal, with the opening and closing the thermostat, the temps vary a bit, as long as you are not in the RED, your car is OK.

eugene22n

Every time I've seen something "odd" going on with coolant temp something bad has happened eventually, like a thermostat going out.

The w221 has an electronic thermo and claims to be better at managing coolant temps than normal mechanical thermos.

With newer cars I've never seen such behavior where you go above the target temperature and then go down. Even in hot places like palm springs and vegas. The cars are good at managing temps. They go up to the optimum and stay there circulating coolant and managing fans as needed.

steveb9771

Check if the electric fan comes on when the temperature is at the upper end. Under this condition, just brake to a stop and leave the engine running. Roll down the driver's window and you should easily hear the electric fan. If you don't, then the cause of your increased temperature is caused by the fan not operating. It might be as simple as replacing a blown fuse. Otherwise either the fan temperature sensor or the fan motor has failed.

Carlos J

I have a 2007 S550 4 matic and my temp gage stays at the 100 mark is this normal?

malahhaor

My old w209 500, w220 500 and now w221 550 were/ are hovering around 90 on warm days.

Jan AMG

What you are describing isn't normal.

carboxy

i agree. i live in south florida and even hot days which is every day.. its always 90

T0ked

The needle has never gone up to 100. Maybe a tick above 90 at the most. Usually hovers around the "85" mark. Only jumps up after a long, hard drive.

cj88

Im having the same problem with my s550 changed the radiator and thermostat now the temperature in the car jumps from 80 to 100 and it's winter, car drives sluggish.driving me crazy could some one please help and give me insight on what s going on and what to do

KNBS550

Official temp should be 89C. When you changed the radiator and thermostat did you do the work yourself? My first guess is there may be some air trapped in the coolant system? Does the auxiliary radiator fan run?

DaveW68

Pushing air out of the system is easy. Just remove the radiator cap before it gets too hot and let the car run at full operating temp for a few minutes. Then put the cap back on and all air should be gone.