Replaced head gasket, Still spraying out coolant within a few minutes of running

[mach1soldier]

Well I had the head decked and a new gasket put on.

Started right up but the water starts running out of the radiator with the cap off almost immediately. If I put the cap on, it will start draining out the overflow in a few minutes.

I even had some nice steam coming from the back of the engine at one point.

If my heater core was clogged, would it cause this?

Just wondering what to check before I scrap the car. I'm not messing with another head gasket.

[SiliconSoul]

If your not going to try again you might as well torque the hell out of the head bolts and see if it seals. Could be a cracked head...

[mach1soldier]

I might try that.

I removed the thermostat and water is actually flowing now. I didn't flush the block though so chocolate milk galore. I want to flush it just to make sure it's not leftover from the last blown headgasket but at this point, I really doubt that is the case.

[Movin]

Air locked in the head will expand as it gets warm. Bleed the air out by jacking the drivers side up a bit to make the air collect on the drivers side of the engine. Bleed the air out by unhooking the little coolant hose. Pour more in until no bubbles stop.

Those cardboard colored pellets for sealing cooling systems, GM advises there use whenever engines are apart and with coolant flush service. They don't plug things up like the liquid stuff does. Water pumps seem to last longer too. They are at the zone or oreilys in a 6 pack. When surfaces are no longer perfect these help seal stuff up. As long as you have the stat out you might as well flush the thing and bleed it after you get the stat in.

The coolant should not be going by the cap so easy, it may be bad and not holding any pressure. Caps that fail to hold pressure often let air back in the system instead of sucking fluid from the jug. It could undo all your work! Replace it if in doubt.

Flush the heater core with a garden hose by unhooking the heater hoses ( both ) from the engine and back flushing into the hose above the starter solenoid.

Don't test drive it until the upper hose gets hot and the radiator fan turns on a few minutes after. Let it cool down, squeeze the upper hose. If no pressure open the cap and top the radiator,if there is pressure wait until it cools enough so that the pressure is gone. After the coolant levels are correct test drive the car.

[mach1soldier]

played with it some more last night. The thermostat couldn't have been opening. It was milky and guessing it wouldn't open. I left it out and flushed the system for 20 minutes or so. I took a 15 minute test drive and it didn't overheat and the water is clear still. Hoping that means my headgasket job was a success.

I am going to add a thermostat back in the next week.

My only question is this. There are two gauge sending units on the head. One on the thermostat housing which I assume is the water temperature and one on the head which I assume is the oil pressure. Is this correct? My water temp gauge never moved while driving yesterday but I had hot air coming from the heater.

[bhearts]

played with it some more last night. The thermostat couldn't have been opening. It was milky and guessing it wouldn't open. I left it out and flushed the system for 20 minutes or so. I took a 15 minute test drive and it didn't overheat and the water is clear still. Hoping that means my headgasket job was a success.

I am going to add a thermostat back in the next week.

My only question is this. There are two gauge sending units on the head. One on the thermostat housing which I assume is the water temperature and one on the head which I assume is the oil pressure. Is this correct? My water temp gauge never moved while driving yesterday but I had hot air coming from the heater.

The one by the tstat is for the gauge cluster. The one in the intake manifold hooked into the same wire bundle that the fuel injectors are hooked to, is coolant temp that the computer uses for fuel enrichment purposes. The one on the back block is simply to trigger the safety low oil pressure light on your gauge cluster.

[1990new]

To add info about the third temperature sensor which screws into the front of the head (just below and to the left of where the little curved rubber hose connects from
the bypass water tube).
It control your radiator cooling fan by cutting power to a spring relay that hold open the switch to the fan when the water temperature
reaches 207 degrees Fahrenheit and above. If your remove the wire to this sensor when your ignition switch is on, the radiator fan should come on even if the temperature is lower than 207F.

[mach1soldier]

Next question. What is a good thermostat? I don't want to drive without one since I'm trying to keep the car hot for best fuel efficiency.

[TominMO]

Next question. What is a good thermostat? I don't want to drive without one since I'm trying to keep the car hot for best fuel efficiency.

That is a question of hot debate around here. :-) An inexpensive but decent stat is the better of the two Stants that all the McParts places carry. Part # 45869 (or 65869). About two bucks more than the cheap one. Made with upgraded metal, as I understand it. You definitely want the one that is 195 degrees, to get decent heat. $5 at Rock Auto.

Or you can go with the open-when-fail type so that if it breaks, it isn't closed. Prevents overheating. Motorad Fail-Safe, part # 7240-192, $6.
Or get the Motorad 414-192 with the dual valves (little one goes to the top, where the jiggle pin would otherwise be). $8. On Rock Auto, do a part # search (414192) to find it.