I have a 99 cadillac eldorado it is overheating i changed thermostat and coolant it still overheats i beleive the water pump works the fans work when put coolant in the over flow it shoots out when it gets full

indicates a blocked radiator cores
not using a thermostat can cause overheating as it allows the movement of coolant to be to fast to allow the transfer of heat from the coolant to the air
the bottom hose will always be cooler than the top hose on a good radiator because of the loss of heat through the fins but if a good cooler then that indicates blockages in the cores

Incorrect timing can also cause overheating along with bad radiator, bad pump, fan not working, bad thermostat, AC, inadequate lubrication, low coolant level, engine load as when towing, etc.
Until issue resolved put your heater on full blast and lower the window.

Are the cooling fans coming on ? Go under the hood in the engine compartment , with the vehicle running have some one turn on the A/C , do you see and or hear the cooling fans come on ? Could be the coolant temperature gauge is bad ! How many miles on the vehicle ? Ever have water pump replaced ?

1

Check for a loss of system pressure.
Is there a loss of system pressure?
--
Go to Step 2 yes
Go to Step 3 no

2

Inspect and repair any faulty hose connections.
Does the engine still overheat?
--
Go to Step 3 yes
System OK

3

Check for low coolant protection (-37?°C/-34?°F).
Is there low coolant protection (-37?°C/-34?°F)?
--
Go to Step 4 yes
Go to Step 5 no

4

Test solution. Replace the coolant if necessary.
Does the engine still overheat?
--
Go to Step 5 yes
System OK

5

Check the water pump belt for low tension.
Is the water pump belt tension too low?
--
Go to Step 6 yes
Go to Step 7 no

6

Replace the water pump belt tensioner.
Does the engine still overheat?
--
Go to Step 7 yes
System OK

7

Check for an inoperative thermostat bypass.
Is the thermostat bypass inoperative?
--
Go to Step 8 yes
Go to Step 9 no

8

Replace the bypass.
Does the engine still overheat?
--
Go to Step 9 yes
System OK

9

Check the water pump.
Is the water pump inoperative?
--
Go to Step 10 yes
Go to Step 11 no

10

Replace the water pump.
Does the engine still overheat?
--
Go to Step 11 yes
System OK

11

Check the radiator fins for obstruction.
Are the radiator fins obstructed?
--
Go to Step 12 yes
Go to Step 13 no

12

Inspect and clean the radiator fans.
Does the engine still overheat?
--
Go to Step 13 yes
System OK

13

Check the cooling system passage for obstruction.
Is the cooling system passage blocked?
--
Go to Step 14 yes
Go to Step 15 no

14

Inspect and flush the system. Reroute or replace the hose if necessary.
Does the engine still overheat?
--
Go to Step 15 yes
System OK

15

Check the water pump belt for damage.
Is the water pump belt damaged?
--
Go to Step 16 yes
Go to Step 17 no

16

Replace the water pump belt.
Does the engine still overheat?
--
Go to step 17 yes
System OK

17

Check the cooling fans.
Are the cooling fans inoperative?
--
Go to Step 18 yes
Go to Step 19 no

18

1. Inspect the electrical connector. Replace if necessary.
2. Does the engine still overheat?

--
Go to Step 19 yes
System OK

19

Check the throttle body circuit flow.
Is the throttle body circuit flow restricted?
--
Go to Step 20
Go to Step 21

20

1. Inspect the orifice and associated hose. Replace if necessary.
2. Does the engine still overheat?

--
Go to Step 21
System OK

21

Check for a stuck thermostat.
Is the thermostat stuck in the closed position?
--
Go to Step 22
--

22

Replace the thermostat.
Does the engine still overheat?
--
--
System OK

This actually sounds like your motor is not the problem it sounds as
thougth your transmission is in need of work. if you have flushed your
system also may look at your oil pump system as the change in pitch of the road to climb hills may infact be pulling sludge against the sump
tube screen and plugging the oil pump. these are the only two reasons I can see for this to happen if system only dose this when climbing a hill
.

coolant leaking into engine probably blown head gaskets. More damage will occur the more you drive it. Unfortunate and expensive repair on a northstar.

Engine coolant temperture sensor, This sensor runs the cooling fans. Before that I would check fuses and relays to the fans.
Randy

Is the fan now working? Your engine will continue to overheat if you have not fixed the fan. Check the fuse for the fan, connectors, and replace the fan if necessary.

check engine temp sensor if ok check fan relay

I am assuming you have the Northstar engine.

Check for coolant flow at the Purge line,this is a common problem on the Northstar.
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.

Are you running it without a thermostat? If so,then strangely enough,this will cause overheating as the Northstar cooling system is different to most conventional systems and therefore will not help you diagnose the problem.

try checking the hoses for blockage,and if not that make sure the fan is working right as it might be the fan cluch,or your water pump may have went out,best of luck