Thanks Mechanics! Now please apply your know how to my sons car?

Question

My son has a 1996 pontiac sunfire. overheating blowing back water out of reservoir, water heater core has been flushed. All radiator hoses are new, new water pump, new thermostat radiator hoses new. Any ideas what
could be wrong? My son thinks it could be a blown head gasket, it is not blowing any white smoke... and I dont think its the head gasket.

Answer 1

Is it possible the thermostat is in backwards? You would have a blockage and pressure buildup.

Answer 2

This is a classic headgasket symptom. However, the head is what actually causes the failure. It warps a fraction of a millimeter and allows the gasses to get into the water jacket. The head has to be gauged and resurfaced if needed before re-installing. I'd make sure the electric fan is coming on or working, first.

Here's a good check. When the engine is cold remove the radiator cap where ever that might be. Then start the car and see if Old Fatihful erupts. If this happens it's the head/headgasket.

It happens, sometimes, that those plastic bottles that now hold the fill cap/pressure cap will leak but it's not really obvious. The best way to check this is to start a cold engine, watch the bottle and see if it fills to the top in short time, like a minute or two. The seam where the bottle "halves" are fused together will eventually fail and let the air out of the bottle and this allows the engine coolant to not be under pressure and this allows the coolant to boil in the head(s). If everything is pressurized, as is usual around 15 PSI, then this would not occur.

The coolant will need to be a 50/50 (water/coolant)mix since pure antifreeze will make the car run hot in Summer.

Good Luck!

Answer 3

Did this come about after the flushing and hose replacement or did you do all of that because it started to blow out coolant?

You did not say but I am assuming you have a 2.2 liter engine. If you do not purge it properly, it could have an air pocket in the system preventing coolant flow and causing an overheat.
It could also be a head gasket problem or a warped head. I ran into your exact complaint on your exact vehicle where I work. It started as a blown hose, which was not shut down soon enough. We replaced the hose, filled it, purged the air and thought everything was fine. Two day later it was overheating and was low on coolant. No leaks were showing up so we filled it again and purged it and watched it and drove it all day. Two days later, phhtt!. Finally I reasoned something sinister was afoot. Pulled the head. Gasket was perfect. Head was warped.
Mind you, it ran beautifully. The leak was small and it was not a fluid leak it was a compression leak, pumping bubbles of air, tiny ones, into the water jacket. Eventually it would prevent coolant flow and overheat and spew out the overflow.

Whew! I am windy!

Answer 4

After reading the other answers submitted this is the conclusion I have come to. The first thing you check is that brand new thermostat. Take it out and bring it in the house and put it on the stove in a saucepan of hot water with a candy thermometer. Heat the water to and past the rated temperature of the thermostat and see if it opens. If it doesn't then take it back to the parts store and exchange it for a new one. Check the new one too. My father taught me to do this when I was growing up and I remember that he bought a thermostat for his 1970 Jeep pickup. He didn't get one that opened right until he had the fourth one from the parts store. If it opens correctly then put it back in and refill with coolant. Make sure you get it full because air in the cooling system can cause pressure buildup and overheating. If you have a bleeder then bleed the pressure off so you can get it full. If you get it full and it is still blowing out water and overheats then you probably have a bad head gasket or a non-functioning cooling fan. Good luck.

Answer 5

Definately a blown head gasket.

The 2.2L engines in the Sunfires were bad for that. I had a 1996 S-10 with the same engine. Same issue. The cylinder block in the center has a portion called the siamese cylinders. The head gasket pops where the water jacket goes through this thin area. If the car was overheated due to a low coolant level, the gasket will fail and cause this issue.

Mine failed because some fool at a Jiffy Jack's Lube Shack decided to add regular coolant to my Dex-Cool System. Needless to say Jiffy Jack's Lube Shack paid for that one and I have never taken ANY of my vehicles back to a Jiffy Lube since. Crap Can Sally's, (Oil Can Henry's) and Crappy Lube, (Snappy Lube) is not much better.

I would recommend that you have the car towed to the dealership and let them do this job. The cylinder head has a particular removal procedure and if you don't follow it, you are going to be buying a new one to the tune of $1400.00, because you warped it during the take down.

Good Luck!

Answer 6

Sounds like head gasket , Just because you get no smoke does always follow that you do get lots of smoke , if the head seepage is small the engine may not leak much when cold but the seepage increases when hot .,To get pressure in the water jacket it can only be air pressure from a leaking head gasket or cracked head or , blocked water system and is overheating and it is steam pressure . Have a water carbon test that will establish whether its one or the other

Answer 7

Has the radiator been checked? Was this a problem before all those things were replaced. Thermostats are really simple things that can fail, even when new.

Just trying to throw out some ideas. I doubt it is a head gasket, unless one was installed incorrectly and it is blocking water passages.

good luck.

Answer 8

if a head gasket blows in a water jacket it will blow water back through the engine and radiator in to the reservoir,and create a lot of back pressure,the don't really have to smoke to have a bad head gasket on them,a good way to tell is when its running look at the radiator hose it may be swelling up on it from pressure,or have pressure check don't on it,this will tell you instantly if it has one blown,good luck on it.

Answer 9

Hi

This sounds very much like a head gasket problem to me, but you best have a cylinder compression test carried out just to be sure, or a garage can put their emmissions tester probe into the expansion bottle and test for combustion gases.

Best regards

Geordie

Answer 10

pull the oil dipstick out and put it to an open flame. if you see smoke thats good but if you see water droplets boiling off than you have a blown head gasket

Answer 11

If bubbles are comming into the radiator it could be a head gasket.Have you changed the radiator cap?