Why would antifreeze be leaking from the back of the engine in a 1999 monte carlo?

Question

antifreeze is not leaking from radiator or inside of car. temp gauge is going from cold to hot to cold.what could the problem be?

Answer 1

Intake gasket..

Answer 2

I am not familiar with that particular car, but engine coolant circulates through the engine block AND the intake manifold to warm the carburetor and provide heat for the car's heater. Like someone else said, check the heater hoses, but also check around the intake manifold.
Going from hot to cold to hot sounds like a thermostat problem. Usually a stuck thermostat will cause the car to over heat, but when the vehicle loses the coolant it can prevent the transfer of heat to the temperature sensor.
A blown head gasket, cracked engine block, leaking heater core or heater hose, blown intake gasket, or other hose can cause the problem. Some more likely than others. Years ago, my car quit, but I could find nothing wrong with it. When I got some help one person watched as I started the car. He called me to look while he started the car. It would start up and then die. There was a small hole in the heater hose that was shooting a tiny stream of coolant directly onto the engine's coil (which made the high voltage to make the spark plugs fire) and grounding it out. By the time I could get around to look inside the engine compartment, the water would have run off and the engine was stopped.

Answer 3

I assume your car has the 3.1 or 3.4L V6, in which case the answer is simple;

The same reason EVERY car with this engine leaks - failure of the lower intake manifold gasket.

These are notorious leakers. I have seen them start to leak with just 12k miles on them! Almost every one that comes into my shop is leaking to some degree or another.

When you have the gaskets replaced I recommend replacing the manifold bolts, distributor shaft O-ring seal, T-stat and gasket and EGR gasket at the same time. Might as well do the valve cover gaskets as long as you are in there.

If your car has the3.8L V6 then the problem is actually not the intake gasket but the plastic intake manifold.

Answer 4

OOPs- The temp gauge is telling you that your coolant is BOILING! Temp gauge is (1) reading cold because no coolant reaches it. (2) reading hot when coolant (or steam) flows past it. When you can smell coolant while you are driving, it means overheating.
First thing, top off your coolant, that will fix things for the moment, tho you should have checked long before this. The leak will reoccur, of course, but now you idle/race engine while in 'park'. If white smoke (steam) shoots out exhaust, that says "blown head gasket" because at least one cylinder is converting leaked coolant to steam. Do you have hard or rough starts when cold? Same thing: cylinder can't fire with coolant contamination. Short answer: it's leaking inside and out.
The fix is expensive- an older car isn't worth the repair: many $$$. Judge value for yourself. The problem can't be fixed with Stop-Leak stuff added to coolant, and will only get worse.

Answer 5

If its truly antifreeze leaking from the engine, not hoses, it would be the head gasket or intake gasket.

But if the temperature guage is going from hot to cold and back and forth I would think its the thermostat. Pretty cheap and easy to fix if you've got some mechanical skills. 10bucks.

Answer 6

Sounds like one of the 2 hoses that go to the heate.Check the clamps for tightness.

Answer 7

i hope its a hose but i cult be a gasket

Answer 8

Could be a freeze plug.