2 Grand Master
Overheating?
CEL lighted and i parked shortly afterward. I opened the hood to find what appeared to be a hot (too hot?) engine with steam coming from the water pump and coolant sprayed around by the fan. After about an hour, i came out of class and checked the coolant level, which was normal, and drove home (about 45mins) with no problems.
- the CEL code is 1223, or coolant temperature sensor
- the temperature gauge on the dash never went above 12 o'clock
Can a faulty coolant temperature sensor allow the engine to overheat without registering on the temperature gauge?
Lowered with blue h&r(?) springs, Bilsteins, tint, 19# design 3 injectors, Dual Magnaflow
southwest WA
3 Grand Master
the steam can't be ignored. as i've been told on this forum about my ford taurus, if an air pocket forms around the temp sensor, it will read normal (or not much from normal). you have a leak or a clog that needs to be fixed, it just so happens that the temp sensor went sideways at the same time.
2 Grand Master
i'm guessing a headgasket issue, but check the water pump first. steam = bad
Major Contributor
It could be faulty thermostat. Bad coolant temp sensor will not cause your engine to overheat. You will just get incorrect reading. And since it doesn't happen all the time, it is not air in cooling system either because it will always overheat if there is air trapped. Changing thermostat is easy and the part is cheap so you should try changing that first.
Originally Posted by Alexlind123
RICK
BMW 1995 525i (Alpine White)
If the coolant temp is faulty = does not read temp properly = temp gauge is not reality
If coolant temp is faulty, computer reading is not correct as well and temperature/air intake/fuel feed ratio might be screwed up. But you see steam, like if engine is hotter then it is usually, not sure if computer bad reading can lead to this...
Like above, if you have boiling coolant liquid, it means bad thermostat, bad coolant pump or bad radiator.
But a combination of both coolant temp sensor and thermostat failure at same time, not lucky.
1993 (build 93/05) 525i automatic M50TU (vanos) 263K miles (ca. 423000 km) in Montreal, Canada (bought the car 9 years ago in San Diego, CA)
3 Grand Master
AFIK there are two temp sensors - one tells the DME how hot the engine is and the other goes to the gauge. I'd say its the former that generated the code and CEL. Sounds very much like your pump is shot and leaking coolant- get your fingers behind the pump pulley and feel if its wet. You may see the odd drip even with the engine switched off as it retains pressure
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