Date registered: Sep 2010
Vehicle: 1997 Mercedes-Benz S500
Location: Bethesda, MD.
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My 1990 560SEL running hotter than usual.
I have a bit of a problem as of 2 weeks ago. I live in Maryland and we had some cold days around here. However, around two weeks ago instead of normal temperature, 87C is the one that I'm used to see on my dash, it started to display 96C. I had a tiny leak between water pump and upper housing, where you connect the hose. I filled less than half a pint of MB coolant and noticed that rubber seal on my cap had seen better days. So, I decided to go to a dealer, got the gasket and new 80C thermostat.
I then took the car to a MB mechanic and asked him to replace the fluid and change the the thermostat and the gasket. He replaced the fluid, didn't flush it, and mixed 50/50 blue MB coolant and water.
I came home and parked the car. Next morning started the car 28F outside let it run for 15 mins and started to drive without turning on the heat. For the first 20 mins of driving the temp was 86C, but later on it started to climb to 95-96C range. Once I parked the temp stayedat 95C. I left the car running and it didn't go up or down. I openned the hood the fan was whooshing air so I guess my clutch is fine.
The upper radiator hose is hot to touch and pressurized. I took infra-red thermometer and measured the temperatures. 85C on upper hose 63 on lower hose. I shut off the car and touched the radiator 83C 0n top 63C at the bottom.
I also tried parking uphill and revving the engine at 3500rpms for a minute to purge the system air out.
Then I tried to drive up the hill in 2nd gear at 35 mph to get the engine under load the temps fell to 86C from 96C.
When I start the car cold in idle the temp never gets over 86C a ran it for an hour.
What are my options, head gasket?, water pump, clutch? air pocket? temp sensor?
'93 Crown Vic 188,600 after 7 years ended up in police impound
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'90 560SEL 198,375(Sold). Will be missed dearly.
'97 S500 Black on mushroom. 137,000 miles