Overheating, but not showing on gauge and no flow to top hose in front of motor
I have a 1997 sls with 120,000 on it and it keeps overheating but the gauge never goes above half and the top hose in front of the radiator never gets even a little warm. It keeps blowing coolant out of the overflow hose and will blow it out of the radiator when the cap is off, however it never blows ANY smoke at all. It will start to get a rough idle when its hot. The only thing I can think of is the thermostat. Where is it located and do you have any other suggestions? Thanks.
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Re: Overheating, but not showing on gauge and no flow to...
Thermostat is stuck closed it is usually located under the flange that your top radiator hose attaches too. but since you didn't include engine information I can't say that with 100% certainty. Usually you just follow the top hose from the radiator. It is attached to a flange that is attached to the motor with two bolts. Remove the hose, remove the two bolts and the flange comes off. The thermostat justs rests in a little depression there remove it and replace it very cheap part. Make sure you use the gasket that comes with the new one. Difficulty rating: easy. Also cheap to have done. There are a couple of Caddy engines though where it is under the alternator and compressor, and the alternator bolt also holds the tensioner for the serpentine belt. Difficulty level goes way up on that one!
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top up with COOLANT and drive around for a short distance not to far from home and watch the temp gauge and see how the engine drives if temp gauge goes into red stop wait for engine to cool at least an hour then carefully remove coolant cap and check if there is any coolant loss, if temp gauge stays at normal you may be lucky
Is it ACTUALLY overheating? Check for heat at the top and bottom radiator hoses, and at both heater core hoses. If one is cold then your radiator or your heater core may be plugged and in need of a individual flush.
Knock sensor. Check all the wiring connections on the engine heads. Your sensor probably is failed (but see Overheating #3 below) .
fast blinking left turn signal. The front bulb has failed, so replace it.
oil temperature light. This may be an indirect result of #1, as the engine is not running properly and this can cause overheating (but see Overheating #3 below)
Other causes of overheating ...
low oil level
low coolant level. If you are losing coolant, the cause has to be located. The correct fill method is to top up the radiator, then repeatedly squeeze the top rad hose, to "burp" all the air out of the cooling system. You will hear the coolant squishing in the top of the engine. Keep burping until the coolant squishing noise stops.
head gasket(s) may be failing, a not uncommon problem for your engine model. Check for oil in the coolant.
Check the thermostat. The temperature sender is to the right of the thermostat and if the thermostat doesn't open the hot coolant from the block won't be flowing to the sender/gauge showing it is overheating. The thermostat is at the end of the top radiator hose where it enters the engine. Check the wires to the sender to make sure they are connected. Flush the coolant and heater core at the firewall connections as it may become clogged.
The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system. There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line. With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating. If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage. The hose goes in to the engine to a crossover and comes out the other side close to the thermostat housing,the blockage may be there.
Can you elaborate more on the burning oil?.....how do you drive the car exactly?......do you baby it or do you floor the accelerator occasionally?........what grade of oil do you use?
The oil burning may also be a consequence of your overheating problem so check the purge line first as described above.
Overheating can be numerous things: Fans not working, water pump, thermostat, overflow cap, and the list keeps going. When the engine is running and heats ups, feel the heat of the top hose, if the hose isn't hot, the thermostat is most likely stuck open and needs replaced. If it is hot we know you have circulation. The cap on the expansion tank may be defective, if it can't hold the pressure of the water, it will release at the overflow cap if the cap is bad. Also check the coolant level.
Allow it to cool down and refill system while running with heater on hot. Hopefully this will get the air out of the system. However, if this condition persists, have the radiator checked for hydrocarbons. These engines are sensitive to overheat and you may have blown a head gasket. (hope not) Good luck!