maniac79

I just bought a 99 trans am , beautiful car 67,000 miles,i'm a novice concerning high performance engines etc. I appreciate any help. This car doesn't overheat at all unless i exceed 85,at 90. My temp just starts going up ,i've never let it get all the way to the red ,i kill the a/c ,slow down ,no prob. I was told my waterpump was leaking but i wanted to know could this be the problem ? Thermostat,radiator is fine but i wouldnt think that a leaking waterpump would cause this issue ,after all if it's bad it's bad right? Wouldn't my car overheat at any speed or temp outside.regardless,thanks for all input ,i'm replacing the pump now.just concerned it may be something greater
thanks
chase

usnfenix

iTrader: (11)

Lol yes I would say your water pump leaking would have an effect on your cooling system.

Summitracing

If your water pump is leaking you should make this repair the first step in cooling system diagnosis. A leaking pump can let air into the system or not have enough flow to circulate chilled coolant from the radiator. We offer a couple water pumps for a 1999 Trans Am along with the LS1 water pump gaskets. You also may want to change your existing coolant with a product like Be Cool Antifreeze. This product has leak stopper, fresh lubricant and other additives that will increase your cooling systems performance. After you install the new pump make sure to purge any air from your cooling system. You can do this by topping off the reservoir and running the engine with out the cap installed. This process can take 10+ minutes from a cold start up and keep an eye on your fluid level since it will fluctuate. You will add more coolant as needed so the system is at the full mark with the engine hot.

LS6427

iTrader: (2)

A leaking water pump itself cannot make you overheat. What happens is....after the engine shutdown the engine cools....when it cools air is sucked into that leaky seal in the water pump. As that coolant drips or squirts out, that air pocket gets larger and larger, then it reaches a point where the air pocket gets stuck on the engine side of the t-stat and that will STOP the t-stat from opening when its supposed to, because only air is touching it, not the hot coolant from the heat coming off heads while the engine is running. T-stat won't open, or opens partially....and its not enough coolant flow (exchange) to keep it from overheating, especially while cruising at 80mph.

Water pumps always circulate the coolant, unless you're one-ina-million to shear the shaft, but what they do is leak from the shaft seal.

Change it.......bleed the system completely of air.

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transamtom

iTrader: (8)

If your car overheats at highway speeds your air dam under the car may be damaged not allowing air up into the rad.

Check the black plastic piece under the front end and make sure its not damaged.

Peddero

maybe you could take your car to service stations as by further heating they would cause radiator to stop working

LS6427

iTrader: (2)

what?

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DaytonaBlues

i had this EXACT problem in a 98. car was FINE temp wise at idle, but as soon as i got on the hiway, the car would start overheating. the problem was nothing more than what someone i think already mentioned...air flow at speed. since our cars dont have a direct path to the radiator, all the air has to come from UNDER The car..that big black airdam under the car can sometimes be loose or broken so when a 70 mph hiway wind speed hits the air dam, it flexs and doesnt push enough air up unto the radiator/ condenser my 98 air dam was broken at the top and flexed so much it was not staying curved enough to get air up into the radiator. i basically had someone make me one from aluminum and problem solved....but..your water pump is leaking...hence i would imagine its allowing the pressure in the cooling system not to build up, causing overheating or air into there.