My daily driver has become a headache-its a 93 sunbird with 120K on it with the 2.0 SOHC. I've been having problems with it leaking coolant lately-it needs 1/4 of a gallon a week. I know head gaskets are notorious on these things and i am getting a little more white smoke then usuall every now and then when i start it when it is cold-but it is completely random the majority of the time it is not excessive.

Anyways, I figured I would put the coolant pressure tester on it to see where it is leaking-so i do that and the system holds pressure fine forever! So now I am completely baffled-doesn't appear to have oil/coolant mixing-it holds pressure fine-yet the damn thing is steadily leaking somewhere and i have no idea where-there are no visible signs. Pressure cap, thermo, water pump have all been replaced in the past year. I don't even know where to go from here? What should I check? This is becoming a pain cause the thing runs hot now and just cycles from right before the red @ 235 (when the fan comes on-don't ask me why they wait so late) to 190 (when the fan goes off) and just goes back and forth cycling between there.

Any thoughts? Thanks for the help guys in advance.

Nick

I think there is a dye test to check for combustion gases in the coolant. Sometimes these things only leak when they're hot, especially a hairline crack in the head.

If it’s the same engine as the 89 gt, it’s leaking water in to the last cylinder on the driver side. The heads are crap, the cooling system is inadequate and if it gets down pint or so on water the head will warp or crack and keep overheating… If you replace the head, the water fill neck will probably need replaced too. The fill neck is kind of over priced for what it is and within a very few months it will rust thru, and leak enough water out to overheat the engine, warp the head, and blow the gasket…. I wanted to donate mine for artillery practice. But that's just my .2.

Along with Geezer's suggestion, remove the cylinder's spark plug and check for cleaniness and a slight green color, if using ethylene glycol.

If plug is green tint, as said, it may be the head gasket.

It would make an excellent tax deduction for 2006 taxes at your local Goodwill or Salvation Army.

Also when pressure testing the system, how long are you leaving the gauge hooked up and fully pressurized? You should be leaving it on at full pressure for at least 15 minutes, if not longer.

Here is another test you can try.. Drive the car until it is at full operating temperature. Then park it.. Wait 10 minutes or so, then raise the hood, and with a glove on, or with a rag on the upper radiator hose-squeeze it. If it is rock solid, you probably don't have a leak, or a very, very, minor one if you do. If the hose is already squishy-you are definitely loosing pressure somehwhere.

As mentioned above, there is a way to test the coolant for combustion gasses. That will eliminate the guesswork. Having to add coolant is a dead giveaway that it is going somewhere. I also think checking the plugs is an excellent idea as well.

Good luck with your project.