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Old 08-15-2007, 08:02 PM
gdmarques@cox.n gdmarques@cox.n is offline
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Join Date: Aug 2006
Posts: 4
500sl overheat/loss of oil pressure

My 1992 500SL did an odd thing last night. During some intermittent stop and go and idling I noticed suddenly that the temp gauge was pinned at the top and then the oil pressure suddenly dropped to ZERO and the red warning light came on. Then the pressure gauge would suddenly read pressure, then drop to zero then pressure, etc. I was a couple of blocks from my house and the car was running fine so I drove it the rest of the way home and parked it. I could hear the coolant gurgling but no bad smells or anything. The next morning I honestly expected the engine to be seized (or some other bad $10k problem), howvwer the car started right up. I noticed the oil pressure gauge pinned at the top though which was new. Since I was due for an oil change anyway I changed the oil (it was dirty but no coolant in it or metal particles) and refilled it with a new filter. The coolant level was a tiny bit low, but no oil in it and pretty clean. After the oil change I started the car and the temp went up faster than normal to around 100C as indicated on the gauge. The engine was still running fine. I noticed the bottom radiator hose was ice cold although the top was hot, so I assumed a bad thermostat, water pump, or plugged radiator. I replaced the thermostat and kitchen tested the old one. The old one was not opening even at the boiling point of a pot of water. The car seems to be running fine now although the temp gauge seems higher than I remember it (running between the 80 and 100C indications.) Anyone have any opinions on any of this and can you tell me what the proper indicated temp range should be on the gauge. The ambient air temp today BTW was around 85 degrees F. Thanks!
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