1999 grand am is overheating

Hi there.
Well you can either have a problem with either radiator outer {dust/dirt in outer core of radiator or clogged up inside were water goes, or soft hoses,blowen head gasket plus a few others ,but first go to garage to were you blow up your tyres and use the air hose and blow out the radiator core where the air goes in, 2 drain out radiator water and then refill with water at 1 ltr at a time and then check your info car book and find how much water the radiator takes ,if it dosent take all the ltrs then the radiator is blocked inside.
if engine runs rough missing etc then get your Head gasket checked out.
When you say no heat is that with heat on gauge or no heat from heater, as it could be heater blockage same as radiator core. So let me know how you get on.

You mean the car is running fine but just No Heat?
If so
-Sound like the heater hoses are plug. or the control valve is no function

-Check the heater control valve and flush the heater unit with water of garden hose from both directions.
Q: How do I know that is working or not?
A: Slide the heater control from Hot to cold or cold to hot and check it turn or not. (If not turn at all. The cable is broken or slip off)

Mai Lor

no pressure in top hose ,where are u losing pressure, the coolant will boil if not under pressure suspect you have a leak or faulty rad cap. some minor leaks dont show until engines warm and are mostly steam leaving little evidence. look for an antifreeze stain or scale deposit around every connection . if electric fanned make sure it works and cuts in before it go,s into the red

COULD BE THERMOSTAT IF TOP RADIATOR HOSE IS NOT HOT AND BOTTOM RADIATOR HOSE GOING TO WATER PUMP IS HOT THE THERMOSTAT STICKING PARTIALLY CLOSE.IF TOP HOSE IS HOT THE RADIATOR,ENGINE BLOCK HEATER CORE NEED FLUSHING OUT.IF WATER PUMP WEEP HOLE LEAKING REPLACE WATER PUMP, FAULTY WATER PUMP WILL CAUSE ENGINE TO OVER HEAT.REPLACE RADIATOR CAP MAKE SURE YOU HAVE 50 / 50 MIX SOLUTION ANTIFREEZE AND WATER IN COOLANT SYSTEM. IF ALL LOOKS GOOD CHECK ENGINE OIL ON DIP STICK, IF OIL IN DIP STICK LOOK LIKE MILKSHAKE YOU HAVE BLOWED HEAD GASKET THAT WILL CAUSE ENGINE OVERHEATING WHILE DRIVING CAR IN SHORT DISTANCE AND ENGINE OVERHEATING.

No there is no relay to the water pump,

replace the temperature sending unit. Its right there by the thermostat. You can get this at any auto parts store. just need an open end wrench to change it. they do go bad(found out the hard way several years back). I hope this helps you

sounds like a problem with the thermostat stuck closed and foorcing antifreese out the overflow leaving you with over heating car replace should fix problem around 20 bucks

try priming the engine block & radiator with water though the hose's & any hose you can squeeze to pump out the air lock with the filler cap off when running, sounds too much air is is in the system & the pump won't work dry.
I had this problem a few times & I ended up practically forcing water into any hose I could re-attach quickly using a garden hose, as the heating system need's priming too !

Yes, you re correct! thats a thermostat issue.

Hi,

Based on your description "hard line from thermastat area has a heat wraparound it goes towards firewall", that would appear to be part of the heater system for the inside of the vehicle and would not affect the overheating of the engine.

Most engine overheating could be caused by:

• insufficient coolant in the radiator or reservoir;
• defective (stuck) thermostat;
• too soft radiator hoses (upper/lower);
• water pump, belt, tensioner;
• clogged radiator;
• radiator fan motor, clutch (if has got one), relay.

Additionally, in a large number of vehicles, the radiator fan motor would only work the A/C or heater is ON.

Corrective action would require determining which is the culprit, pls try:

• remove the thermostat completely out and test drive, see if the overheating comes back, if yes, then it is not the thermostat, if no then the thermostat most likely is stuck closed and would need replacement;
• on start from a cold engine, remove the radiator cap and pls check if the water flows when the engine is revved. If yes, water pump is working, if not, water pump is defective;
• in a closed loop cooling system such as in your car, there is a possibility that the radiator hoses might have thinned down or gotten softer. This could be checked by revving the engine while looking over the hoses, there should be apparent sagging or reduction in diameter when the engine is revved. If any, then they are too soft and would need replacement;
• clogged radiators could be flushed/cleaned by removing the drain plug at the bottom.
  

Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards. Thank you for using FixYa.