Please help, coolant problem

[me_190]

I am buying an 84 z28 from someone, and they installed a new radiator and water pump, but the car overheats really fast now, i am realatively inexperienced in cars so any help would be greatly appreciated, and by the way, there is no heater core or thermostat, PLEASE HELP ME

[silicon212]

Originally Posted by me_190

I am buying an 84 z28 from someone, and they installed a new radiator and water pump, but the car overheats really fast now, i am realatively inexperienced in cars so any help would be greatly appreciated, and by the way, there is no heater core or thermostat, PLEASE HELP ME

There are lots of reasons why a car could overheat. The water pump, hoses, radiator and thermostat are some large causes, but there's other things such as blown head gaskets, slipping transmissions, plugged exhaust (catalytic converters etc) on down the road that can cause an engine to overheat. Rebuilt engines that have been overbored substantially (i.e. .060 inch) tend to run hot. If the radiator was replaced, it could be too small for the engine. It could also not contain enough coolant (check to make sure it's full to the top with the cap off, COLD! Always keep some coolant in the overflow).

If the car has the stock fan clutch, try to spin the fan by hand with the engine off. Give it a good push - it should spin without any binding, but only for a little bit (1/4-1/2 turn). If it spins too freely or makes noise, this could be the problem.

If power substantially falls off at higher speeds and the engine gets hot, suspect a plugged catalytic convertor or other exhaust restriction. If it overheats while the car is parked and running or moving slowly, but cools somewhat with higher speed, expect a problem with the fan/clutch. If the car has plenty of power yet overheats in all ranges, with it getting hotter faster as you go faster, then expect some other cooling system problem such as too small capacity. Also check the radiator cap to ensure that it seals properly. Cooling systems are under pressure in order to increase the boiling point - if the radiator cap leaks or is left off, chances are the coolant will boil out before the engine overheats, and the lack of coolant will cause severe overheating. Don't overlook the condenser coil in front of the radiator if your car has A/C, this can be plugged with miles of road use and will prevent cool air from reaching the radiator.

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If the engine has been seriously overheated, change your oil and filter at once, if you value your engine's bearings. Overheating leads to broken down oil, which leads to things like spun bearings and the need for a rebuilt engine.

[wrightz28]

ALthough all of the above recommendations are good, let's keep it simple for a second.

First why did they replace the rad. and pump? It was overheating already? I would be looking at thermostat as cheap insurance. When the motor starts warming up and gets in the 185 range feel the upper hose to rad. if it's not getting hot there's your problem. Err, wait a senond, there is no stat, put one in!

Secondly make sure the rad. cap is the right one. And in good shape. $5, more sheap insurance

Third, hoses, make sure they are up to snuff. I would assume that since the systaem has been worked on they would have been inspected, BUT that's not always the case. AND, most importantly, the lower rad. hose shoud have a coil in it to prevent the hose from collpasing under engine vacumm. If it's not there, you're not flowing coolant through.

Finally the coolant, make sure it's mixed properly (hydrometer $2 at the store) and when the motor is cold, open the rad. up, and start the car. Check the level in the rad. do this especially after you install a thermostat, when it opens, the coolant will go down and need topped off. oh and if you happen to see alot of bubbling inside the rad, that could be an indication of bigger problems.

[abaird]

The car definitely needs a thermostat. Also, make sure all radiator shrowds and air dams are in place, believe it or not, they are there for a reason.