Engine overheat and oils spots under the car this 2000 sable has only 50K miles and the engine overheats, coolant levels are ok, no leaks (coolant), there is also an oil leak 3 or 4 drops overnight as far as I can see., previous owner didn't took care of it. I would like some advise as to how to fix these issues.

Have the coolant checked for hydrocarbons. It sounds like a blown head gasket, but from the cylinder into the water jacket. Under higher pressure the engine heat/exhaust gases will enter into the coolant and pressurize and overheat the system. Then with the additional pressure, water vapor will bleed back into the cylinders and burn off as white smoke. This doesn't seem like a fully blown gasket, but one that has a tiny leak under higher pressure and heat conditions. It will eventually get worse.

Could be a bad water pump, sounds like the pump has shot being. That's why it turns hard. if the pump doesn't turn then no coolant will flow through the engine. That will cause the engine to overheat.

First, you need to check your engine coolant level. If the level is low, the first thing to quit working is the heater. And of course if the engine is low on coolant it will overheat.

If the coolant is low then you need to check for the source of the leak, like a bad water pump, leaking hose or clamp, thermostat gasket, or just about any other gasket that seal off the cooling system.

Don't operate the vihicle if it is low on coolant, this can cause hot-spots inside the engine and can cause damage. Top it off with coolant, start it up and check for leaks.

Let us know what you find so we can be of further assistance.

If you did not replace the water pump it could be the issue. Or you still have air bubbles trapped in the system.

YOU NEED BLEED COOLANT SYSTEM.CHECK COOLANT LEVEL IN RADIATOR.ADD MORE DEXCOOL UNTIL COOLANT LEVEL IS CLOSE TO RADIATOR SPOUT.CRANK ENGINE LET IDLE UNTIL TOP RADIATOR HOSE GET HOT.WATCH TEMPERATURE GAUGE.IF TEMPERATURE GAUGE START RISING TO HOT ZONE.TURN OFF ENGINE.LET COOL DOWN.USE LARGE RAG SLOWLY OPEN RADIATOR CAP A LITTLE AT A TIME UNTIL ALL PRESSURE RELIEVED.REMOVE RADIATOR CAP.ADD MORE COOLANT.CRANK CAR AGAIN LET IDLE UNTIL TOP RADIATOR GET HOT.KEEP EYE ON TEMP.GAUGE ALSO.WHEN TEMP.GAUGE STOP CLIMBING.YOUR COOLANT SYSTEM BLED.WHEN DONE LET CAR SET A WHILE CHECK COOLANT LEVEL.ALSO FIRST THING IN THE MORNING CHECK COOLANT LEVEL AGAIN.AND BESURE ADD COOLANT IN THE OVERFLOW JUG TO THE COLD MARK.DONT OVER FILL THE COOLANT RESERVOIR JUG.WORK SAFELY DONT GET SCALDED.

Your coolant level is probably low. When you are driving, the water pump turns faster and pumps the coolant into your heater core. When you slow down or stop, the pump doesn't turn as fast and can't get the coolant pumped into the heater core. Eventually if you don't fill it, you won't get heat at all, and soon after your engine will overheat.

You need to check your coolant level when the engine is COLD, or you take the risk of burning yourself. Hot coolant is under pressure, and will cause severe burns if you open the radiator cap when the engine is hot.

More than likely there is a leak that needs to be addressed. Take the vehicle to a certified repair shop and they can perform a pressure test (at little to no cost) to help you determine where you're losing coolant.

Hope this helps!!

Whatever you do, NEVER allow this engine to overheat and always use the correct antifreeze (DEX COOL) or you will damage your heads severly. The heads were made from aluminum so there is a very serious warping issue on the 1998 Cadillac Northstar engines. There should have been a recall but wasnt, ended up costing me 3 thousand USD to fix the engine problems I had but she now runs fine. I only had the car 4 months before this happened so someone prior to me owning evidentaly let it overheat on too many occassions and I had no choice but to fix cause I was still paying on the car!! Good luck

is time to change you termostat, or radiator work good luck

check condition of radiator,radiator & heater hoses,look for spots wet w/ coolant.look more or less straight up above where coolant puddles on ground.engine block is equipped w/'freeze plugs' that sometimes corrode & leak.washing suspected area of leak with an engine degreaser product may aid in locating source of leak.

no fan comes on when engine cold start up .but it will come on when you turn on air conditioning or defrost on .if engine idling a while when temp get 190 degree the fan will kick on.if over heating you got air in system .wait until cools check coolant add more .crank engine let it idle few. minutes when start warming up turn off engine wait a while before removing radiator cap so you wont get scald.add more coolant .crank it again starting warming up turn off engine wait a while .add coolant .keep doing this procedure until your coolant stop dropping off .if you do this more than 6 times you got a leak some where.check crank level for signs.if oil level higher than normal.if everything looking good.when engine cool make sure add coolant to over flow jug cold level mark.