Temperature displays from 199 up to 128 degrees during various times driving... particularly in slow traffic will go up to 128. Will cool down the faster the car is run on most occassions. Radiator full of properly mixed antifreeze. No leaks detected. Replaced water pump 2 years ago. Front grill clean.
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Re: 1998 Cadillac DeVille Overheats
The cooling fans will not come on until 225 degrees. Normal temp is around 199-215. Sitting still in traffic most will inch up around 220 or so. When you turn ac on it turns the fans on and may cool down engine, Check fan operation.
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Temp is going up, well that doesn't mean anything unless it actually overheats, in traffic it can reach 240 F and present no danger of engine damage. If this is not the case DO NOT DRIVE THIS UNTIL THE PROBLEM IS FOUND AND REPAIRED UNLESS YOU WANT TO BUY ANOTHER ENGINE JOB.
The 1991 Cadillac DeVille 4.9 engine incorporates a magnetic timing probe hole for use with special electronictiming equipment. Malfunction codes may be set during ignition timing adjustment procedure.Enter diagnostics and clear trouble codes if this occurs.#1 Place transmission in park .#2 With the ignition in the Off position attach a timing light to #1 spark plug cable .#3 With engine at normal operating temperature and air conditioning OFF,take off the air cleaner upper housing. The engine should be OFF at this point.#4 Jump pins A and B at the ( ALDL) connector.while not in diagnostic display.SET TIMING MODE message will apear on the climate control Driver Information center.#5 Start the engine and aim the timing light the timing mark loosen the distributor hold-down nut. While observing the timing mark, rotate distributor untill the line indicates the correct timing .This sets the base timing at 10 degrees BTDC at any speed under 800 RPM in the (PCM) The PCM controles the timing throughout the intire engine RPM range.This is the best imformation I can offer you good luck.
At idling speed an engine does build up a lot of heat and the cooling fan will kick in. In slow moving traffic or traffic jams the temperature gauge can touch the red - particularly on hot days. The reason it cools down when you start moving is because of the air flow through the radiator.
Presumably there are no leaks from the cooling system otherwise you would have mentioned it. In normal circumstances the fan will not be running as you are driving at speed, as the air-flow through the radiator is sufficient to cool things. The fan only kicks in to get rid of excess heat - and this usually occurs at idling speed or after you have parked the car.
If the fan is running all the time as you drive, this points to either a fault in the fan switch, or the car is running too hot. presumably in normal driving the fan isn't running and the temperature gauge reads normal?
It is common - in stationary traffic many cars overheat (particularly big engined models) try to stall and 'cut out'. Restarting can be difficult until the engine cools down.
Is your car overheating in normal driving conditions or just at idle speed? Overheating in normal driving conditions can be caused by things like a failing water pump, blocked radiator, collapsed hose, faulty thermostat or, in the worst case scenario, cylinder head problems.
Overheating at idling speed is 'common'. Check your coolant level. If your car isn't using/losing coolant then there probably is no major problem. You can flush out the cooling system and refill with new coolant - and also check your radiator. Are the cooling fins crumbling with age? Or maybe they're partly clogged with insects and debris from the road? A blast with a hosepipe wil sort that out ..
The question is how much does your car overheat in normal driving? If it doesn't .. it appears as though you have nothing to worry about as such. Most cars have 2 speed fans... the 2nd faster stage kicks in at some point dependant on engine temperature. Perfectly normal.
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. Also note that the cooling fans don't come on until the coolant temperature hits around 225 degrees. During normal highway driving the fans will very rarely come on(if at all) due to constant air flow through the radiator.They will only usually come on in heavy traffic conditions on a hot day. But......if you have the Air Con switched on, the fans will run all of the time.
really sounds like your elevtric cooling fans are not working let it run in your drive way with hood open for a while and see if they ever come on they should come on somewere between 210 to 220 or so,[not exact specs just around there]
The most common overheating problem with the Northstar engine is a blocked purge line. It's job is to purge air out of the cooling system. There is a small diameter hose coming from near the top of the coolant tank,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 to near the thermostat housing,the blockage may be there.
Entirely possible and in range. Depends on outside temps and type of driving. The radiator is colled by electric cooling fans, controlled by temp sensors. Fans should come on automatically when a/c is turned on