Overheating problem on a 1998 BMW 318ti

If your 1998 Cutlass is overheating and the heater is blowing out cold air, and you are also noticing that coolant is leaking out, there are a few possible causes. Here are some things to check:

Check for a coolant leak: Start by checking the engine and radiator for any visible signs of a coolant leak. It's possible that a hose or other part of the cooling system may be damaged or loose, causing coolant to leak out.

Check the radiator: If the radiator is not working properly, it can cause the engine to overheat. Check to make sure the radiator is not clogged or damaged.

Check the water pump: The water pump circulates the coolant through the engine. If it's not working properly, coolant may not be flowing through the system correctly, causing the engine to overheat.

Check the cooling fan: The cooling fan helps to keep the engine cool by pulling air through the radiator. If it's not working properly, the engine may overheat.

Check the thermostat: Even though you recently replaced the thermostat, it's possible that it's not working correctly. A faulty thermostat can cause the engine to overheat.

It's important to address any issues with the cooling system as soon as possible, as overheating can cause serious damage to the engine. If you are not comfortable diagnosing and repairing the issue yourself, it's recommended to take your car to a qualified mechanic.

If your vehicle's radiator is overheating and there are no visible leaks, it is possible that the problem could be caused by a faulty thermostat or water pump. These components are responsible for regulating the flow of coolant and water through the radiator and engine, and if they are not functioning properly, it can cause the engine to overheat.
To determine if the thermostat or water pump is causing the overheating issue, you will need to perform some diagnostic tests and checks. Here are a few steps you can follow:

1. Check the thermostat: The thermostat is located in the engine and controls the flow of coolant through the radiator. If the thermostat is stuck in the closed position, it can prevent the coolant from flowing and cause the engine to overheat. You can test the thermostat by removing it from the engine and checking it for proper operation.
2. Check the water pump: The water pump is responsible for circulating the coolant and water through the radiator and engine. If the pump is not functioning properly, it can cause the engine to overheat. You can test the water pump by removing the drive belt and attempting to turn the pump by hand. If the pump is seized or not turning smoothly, it may need to be replaced.
3. Check the coolant level: Make sure that the coolant level in the radiator is at the proper level. If the coolant level is low, it can cause the engine to overheat.

If you are unable to determine the cause of the overheating issue, it is recommended to have the vehicle inspected by a mechanic who can perform a more thorough diagnostic test and identify the root cause of the problem. They will be able to recommend the appropriate repairs to fix the issue and prevent further overheating.

A worn water pump is the most likely. If the coolant is going down, the water is going somewhere.

The most common reasons an Oldsmobile Alero is overheating are a coolant leak (water pump, radiator, hose etc.), the radiator fan, or a failed thermostat. Coolant leak (water pump, radiator, hose etc.)

Oldsmobile Alero Overheating - RepairPal

Videos on overheating. You probably have air in the system from when you replaced the thermostat. The coolant system needs 'burping' of air.

https://www.google.com/search?q=2000+Oldsmobile+Alero+running+ho

Burping

https://www.google.com/search?q=burping+coolant+system

..

Depends on where it is leaking. if radiator or any of the rubber hoses, they have to be replaced. If it is the water pump or coolant pump, major repair to replace it.

Thermostat housing has O rings that can be replaced. Metal coolant pipes may get corroded at the tips that makes it loose its seal.

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Install The Latest Software And Driver Updates From HP Support Assistant

Overheating can seriously damage a car's engine if left unchecked. Although overheating simply means that a car's engine temperature exceeds normal operating temperatures, the causes of overheating are varied. What follows is a brief list of some of the most common causes of engine overheating.

Faulty Radiator
1. A car that overheats will often have a faulty radiator. A radiator is responsible for cooling hot engine coolant that picks up heat from inside a car's running engine. A radiator "radiates" the heat from engine coolant out into the outside air. A faulty radiator loses its "radiating" effects and allows engine coolant to become overheated, thus rendering it ineffective at adequately cooling and engine.
Faulty Water Pump
2. A faulty or malfunctioning water pump prevents adequate engine coolant flow and can cause a car to overheat. A water pump serves to pressurize and propel engine coolant throughout a car's engine and radiator to increase the heat-reducing capabilities of engine coolant. A faulty water pump loses its ability to adequately pump and propel engine coolant, and can cause a car to overheat.
Coolant System Leaks
3. A leaky engine coolant system reduces the level of circulating engine coolant, which increases engine temperature and leads to engine overheating. Radiators, water pumps, and coolant system hoses and seals--all of these coolant system parts can develop leaks, which can result in low coolant levels and engine overheating.
Faulty Thermostat
4. A car thermostat regulates the flow of engine coolant. A thermostat is a heat-sensitive valve that opens when a car engine reaches a set operating temperature and closes when a car engine is cold and warming up. If a thermostat gets stuck in the closed position, coolant will be prevented from reaching the engine, which will quickly lead to engine overheating and potential engine damage.
Low Engine Oil Level
5. Engine oil, in addition to lubricating an engine's internal parts, helps to keep engine operating temperatures reduced by eliminating friction within the engine. If engine oil levels are low, friction and heat build up inside an engine, a condition that causes increased engine operating temperatures and can lead to engine overheating.

After the car is cool and has been sitting for a while, remove the radiator cap, have someone start the car, the coolant in the radiator should drop a little, and there should be movement, if there is no movement, let the car run for a while, with some systems it won't cycle enough to notice until the engine warms up. If there is still no movement, you likely have a bad water pump and/or thermostat.
Another method as a "just to be sure", drain the coolant overflow tank, and fill it with clean distilled water. Drive the car for a few days (carefully not to overheat it obviously, if the engine is getting too hot to drive normally don't do this test). If after a few days of driving the fluid in the overflow tank is still clear (water), then there is no circulation in the system.
It's usually best to start by replacing the thermostat, and then re-check. If that doesn't fix the problem it is most likely a water pump, or in very rare cases a plugged radiator or coolant passage.

This is typical of BMW 318 and others I suppose.
If after changing the radiator, the hoses, the water pump then the other cause is leakage of coolant at the back of the engine block.

This is hidden but there is a hard plastic outlet which gives away after 5 or more years. If the leakage is serious you can notice the coolant disappearing very fast.

Worse it could be the gasket leaking.

Hello Ranger Joe, eight months and two radiators is very uncommon. Question, Have you visually confirmed the leak in the radiators or is the leak near the hose connections? Replacing the radiator, cap, water pump, & the thermostat leaves only two others, the hoses and the engine block/heads. Far fitched will be something or somebody poking holes in the radiator.

You actually need the thermostat in to pressurize your cooling system or the coolant won't cyle through the radiator, it'll just cycle around the engine. Most people think without the thermostat in the coolant will just pump freely through the engine and radiator, but it doesn't.

Chuck in a new thermostat, purge the air out of the system and see if it overheats then. I gaurentee it won't, if it does then you've got head problems (but they should already be obvious by now).