My daughter's '96 Cavalier is overheating. At first I thought it may be the thermostat (it still may be), if I drive the car for about a mile the gauge climbs up to H. The overflow tank is full and antifreeze comes out the top. I have heat as long as I rev up the engine. At a loss, any help is appreciated.


Thank you,

Ted

No heat till you rev it up..... You have an air pocket in the cooling system. If you didnt recently have the cooling system worked on then the head gasket is blown, Its pushing exhaust gas into the cooling system and the engine to overheat because of the air pocket. When you rev it up the water pump forces water through the heater core filling up the air pocket, giving you heat.

There may be a slim possability that the thermostat is causing it, but I doubt it. To check it , just remove it and see if it continues to over heat.


01 cav w/01 3400 gam gt 4t45e

Even if the thermostat was the problem, I dont really see it being the problem causing no heat. Doesn't the coolant circulate to the heater core without going through the thermostat?

I drove it home last night (about a mile), sat in the driveway with it running, plenty of heat, did not have to rev up the engine. As I sat there I had the hood open, I reved up the engine, the temp gauge went up a little past 1/2 way. Then I could see the thermostat open (water went down it the overflow tank), gauge went down to about 1/2 way. Then the temp started to climb, the fan came on lowering the gauge, then after about 5 minutes the gauge climbed back into the H. In total I sat there probably about 15-20 minutes, did not have to rev the engine to get heat. Could part of the radiator be clogged/blocked? I checked around the head (especially the driver's side front) and saw no leaks in the gasket.

Ok, now I'm totally confused. I started the car up today, let it run for about 1/2 hour revving up the engine, and I couldn't get it to overheat?????


Thanks,
Ted

Are You running the orange colored dexcool?


01 cav w/01 3400 gam gt 4t45e

Quote:

Could part of the radiator be clogged/blocked? I checked around the head (especially the driver's side front) and saw no leaks in the gasket.

It's possible that it has a bad radiator. I'd look into that, maybe take to a radiator shop and have them look at it. From your last post it sounds like it's fine sitting but when you drive it'll overheat? When you're driving with a load on the motor, it would naturally make more heat.

Yes, running dexcool (orange juice). Maybe I should flush the system?


Thanks again,

Ted

sure wouldnt hurt to check the water pump out, just to make sure it is moving fluid like it should

this may be a dumb question but is the fan working

Yes the fan is working, it's one of the first thing I checked.

Thanks

Just replaced the thermostat. Now I have added antifreeze, but when I try to bleed the system, I either get spurts of antifreeze, nothing and mostly steam if I rev up the engine.

Any more ideas? waterpump? radiator?


Thanks,

Ted

Sounds like a blown headgasket is pushing exhaust into the system.


----------
2000 Cavalier Coupe, 138k miles, 2.2 Auto, Silver (alive)
1999 Cavalier Sedan, 237k miles, 2.2 Auto, White (dead)

Checked around the head, I cannot see any leaks, and the oil does not look "milky." I checked the radiator, the top hose is very hot , and the bottom hose is cold. The driver's side of the radiator is hot to the touch, but I can put my hand on the passenger's side. A new radiator, maybe?

Thanks,
Ted

from what you just said it sounds to me like a warp head.
the oil doesn' t have to be milky. smoke from the cylinder could easily be penetrating the head gasket and increase pressure to the cooling system causing the thermostat not to open and the coolant not circulate.

The thermostat must be opening, I am getting plenty of heat. I am in the process of changing the radiator and water pump. If this does not help, then it must be the head gasket?

Thanks,
Ted

Well I changed the radiator and water pump, it's still running hot, but when I open up the cap for the overflow tank the gauge drops back down to half way, and it sucks the antifreeze into the system. Could this be air in the system? I am bleeding it from the bleed screw on the line that goes into the heater core. Is there another bleeder somewhere else that I am missing?

Thanks,
Ted

did you fill it back up to the full line when it went down into the system?

Don't quote me on this but I thought there was a tech. Bulletin on them for where the hose connects to the upper part of the radiator. Its really rough inside and creates problems with overheating. Needs to be sanded.

I will include the tech page for the service fill for your car.

The use of mechanical fill equipment is not recommended.

Coolant Service Fill Procedure (WITHOUT ENGINE VENT LINE)

1. Close the radiator drain valve and remove drain tube.

2. Install all engine block drain plugs if previously removed.

Use pipe sealer when installing drain plugs.

3. When adding coolant, it is important that GM Goodwrench DEX-COOL (orange-colored, silicate-free) coolant meeting GM specification 6277M be used. If silicated coolant is added to the system, premature engine, heater core, or radiator corrosion may result. In addition, the engine coolant will require change sooner - at 50,000 km (30,000 miles) or 24 months.

4. Open BOTH bleeder valves - one on the heater return pipe and one on the water outlet (see Figure 1).

5. Fill the cooling system through the surge tank until coolant is expelled out BOTH bleeder valves.

6. Close bleeder valves.
7. Top off coolant level in surge tank to a level even with the flat horizontal wall below the vent lines (approximately 1" below fill neck), (see Figure 2).

Important : Leave surge tank cap off.

8. Start engine.

9. Open water outlet bleeder valve and leave valve open until a solid stream of coolant is expelled, then close valve. Repeat this every 3 minutes until the thermostat opens.

Important : Thermostat is considered open when upper radiator hose is hot at radiator connection.

Important : Turn HVAC controls to "Heater", Full Hot and check for warm air during the first 5 minutes after engine start. If no hot air is present, start procedure again at Step 4.

10. Top off coolant, if necessary, to the same level as in Step 7.

11. Install surge tank cap.


Coolant Service Fill Procedure (WITH ENGINE VENT LINE)

1. Close the radiator drain valve and remove drain tube.

2. Install all engine block drain plugs if previously removed.

Use pipe sealer when installing drain plugs.

3. When adding coolant, it is important that GM Goodwrench DEX-COOL (orange-colored, silicate-free) coolant meeting GM specification 6277M be used. If silicated coolant is added to the system, premature engine, heater core, or radiator corrosion may result. In addition, the engine coolant will require change sooner, at 50,000 km (30,000 miles) or 24 months.
4. Open the bleeder valve on the heater return pipe (see Figure 3).

5. Fill the cooling system through the surge tank until coolant is expelled out the heater return pipe bleeder valve.

6. Close bleeder valve.

7. Top off coolant level in surge tank to a level even with the flat horizontal wall below the vent lines (approximately 1" below fill neck), (see Figure 2).

Important :Leave surge tank cap off.

8. Start engine and warm engine up until the thermostat opens.

Important : Thermostat is considered open when upper radiator hose is hot at radiator connection.

Important : Turn HVAC controls to "Heater", Full Hot and check for warm air during the first 5 minutes after engine start. If no hot air is present, start procedure again at Step 4.

9. Top oft coolant, if necessary, to the same level as in Step 7.

10. Install surge tank cap.






99 cav 2.2L 212,000 miles
97 cav 2.2L 110,000 miles
91 cav 2.2L 236,000 miles RIP
04 Silverado Z71 Ext.Cab 55,000 miles
01 Suzuki SV650 22,000 miles
97 Arctic Cat ZRT 600 6,000 miles

Cracked head, Those heads crack between the exhaust and intake valves which allows compressed exhaust to enter the cooling jacket.
To verify this, fill the coolant jug with the engine off, go just to the full line, run it at an idle, If It pushes more than a gallon out then wants to suck more back in, then push it back out and has lots of bubbles then Its got a crackes head.
They do make a tool that has blue liquid in it and you hold it on the rad fill while its running, if it turns green then you have exhaust entering the cooling system. Its either available at Napa or Snap on, not cheap though.


01 cav w/01 3400 gam gt 4t45e

Not pushing antifreeze out, ran it for about 10 miles, the gauge stayed at 1/2, then on the way home it went up to about 3/4, but did not overheat.

Thanks,
Ted

Are you implying that 3/4 up on the guage is over heating?
That actually sounds pretty normal believe it or not. As long as the cooling fan turns on and the guage drops to half way then there is nothing wrong.
Over heating is when the engine systems cannot control the engines heat. and things occur like forcing the coolant out the over flow.
Some simple things cause this like a bad thermostat, watered down coolant, to a cracked head.
Sounds like your daughters cav is fine.


01 cav w/01 3400 gam gt 4t45e

But the gauge does not drop back down to 1/2.

Thanks,
Ted

"But the gauge does not drop back down to 1/2."
It doesnt necessarily have to run at half way, especially in park ideling.
Depending on the temp outside, while driving it, it should go to half way, especially if its cool weather. Warmer weather not so much in the center but in that area on the gauge.




01 cav w/01 3400 gam gt 4t45e

Go outside and check the oil.
Tell us exactly what the color of the oil is and if the oil is higher than normal.