Mach85

Being I'm not as familiar with the vette I ask you..... I just got the car running and was letting it idle to check out the Temp. The fan was not coming on the temp rose to 228 and I heard the water boiling in the radiator. now with the old hot rods that sometimes means alot of things what I fear it could mean is a head gasket problem or worse. I open it up to your thought's. It is a 85 completly stock I did jump the fan to kick on at the ALDL it works fine.


[Modified by Mach85, 7:55 AM 5/13/2003]

GlockLT4

you have too much water in your coolant. Shouldn't mean a bad head gasket. Add more coolant (not water) to raise the boiling temp. Also, I would burn a chip for that thing that has the fans come on at lower temps. Mine are on at 185. :cool:

CentralCoaster

Also, if you let your overflow reservoir run dry, the system can pull more air in.

If your coolant system has a bunch of air in it, it can't pressurize easily and will boil at a lower temperature.

(Water boils at room temperature if the pressure is low enough. I've seen it! in a vacuum chamber of course...)

:auto:

SBNova

just a note- coolant lowers the boiling point- it doesnt raise it, hence the term "antifreeze".

Nathan Plemons

Absolutely untrue.

some bottles used to even say Antifreeze / Antiboil

Pure water will boil much faster than a proper antifreeze / coolant mix. Go find a jug of antifreeze and read the back. It will give you freezing & boilover temps for certain mixtures.

T1Kilr

not that I am trying to :boxing

but shouldn't it read " coolant lowers the freezing point and raises the boiling point" ??

Ramanstud

Add coolant and make sure the system is completely full. You can also sometimes acquire air pockets which also create local hotspots and other difficulties.

:cheers:

Steel Blue 91

:iagree:

You may have air trapped in the system. Start the engine when cold without the radiator cap. Wait for the stat to open. Have someone rev to about 2000 rpm and hold it there. Add coolant to fill the system and replace the cap. You might have to do this two or three times to get all the air out.

PurpleC4

For what its worth ~ the first thought that came to mind is a blown head gasket. Water will boil at 212 degrees F. when it is at atmospheric pressure and at sea level. If your fans are running, the thermostat is open, and the radiator is unobstructed ~ even pure water will not be boiling in your radiator.

Have you verified that the T-stat is functioning properly? Obviously you can remove it and test it in a pan of water on the stove ~ but they are so cheap so why take a chance. The test will confirm your suspicions though. Just drop it into a pan of water and turn the burner on. The stat should start to open just before the water starts to boil (provided it is a 195 degree T-stat or close to it).

You can run a compression check on all the cylinders if you suspect a blown head gasket. The most accurate way to do this is to remove all the plugs ~ then check each cylinder while the plugs are removed. You should allow for 3 solid compression cycles for each cylinder.

~ Purp


[Modified by PurpleC4, 8:42 AM 5/13/2003]

0ski_dwn_it

Guys,

I think you all missed a key thing...I just read through the post pretty quick, but in his opening post he said That is why he is overheating! Not the amount of antifreeze etc. Alhtough I understand what you are trying to do with adding antifreeze. The bigger problem is still his fans needed to be jumped.

To whom posted the question, you need to make sure the fans are coming on! If they aren't then you need to track down your wiring problem, since its not a fam motor if it came on when you jumped it off the ALDL. :cheers:

GlockLT4

:nono: :nono:

GlockLT4

Well, he did say "fan did not come on, and temp rose to 228". The fans aren't supposed to come on until 228 and 235 anyway. (at least that was stock on my '94 - not sure about other years).

Mach85

Thank you all very much. I love this forum. When I was a teenager I did not have this forum and did everything the old fashion way. I can't tell you how cool it is to be able to post a problem and have my memory woke up to things I may have forgot.

I decided to drain all the fluids and I mean all of them and replace everything. Also remove the radiator and boil it and flush the block. Change the thremostat. Add a chip.

Thanks for all your responses.

Mark

ToddAT

Has anybody mentioned checking the radiator cap yet? The pressure in the system is the primary method of preventing boilover. The glycol coolant has some effect, but not a lot. There are alot of people that run straight water in their cooling system, since plain water is a much better coolant than a mixture of coolant and water.
If the cap leaks the system pressure cannot build up and you will get boiling at some point. Caps do go bad.
Make sure the system is full, make sure the fans are working when they should, and make sure the cap and thermostat are working like they should.

CentralCoaster

Wow, all the misinformation here makes me glad I went to college.

Most mixtures keep water in the liquid state longer. This means, the boiling point raises AND the freezing point drops. It can especially drop the freezing temp. Antifreeze prevents the water molecules from organizing into ice crystals. Kinda like how moving water prevents the water molecules from organizing into ice crystals.

Water only boils at 212 at sea level at ATMOSPHERIC pressure (1 atm or 14.7 psi). This doesn't apply to your cooling system. That's why you have a radiator cap. :yesnod: This helps maintain system pressure when its hot. If water pressurizes, the boiling point goes up. If you pop the cap off, the pressure drops, and the water flash boils, and continues until the remaining water is at 212F.


[Modified by CentralCoaster, 2:28 PM 5/13/2003]

CentralCoaster

[Modified by CentralCoaster, 2:32 PM 5/13/2003]