is this a blown head gasket ?

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nicoles

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I have a 66 barracuda with a 273 2bl carb. after it warms up i've noticed that I have pressure built up in the radiator .I'll take the cap off and the water boils out . I checked the water temp and it said 185 .also the gadge read normal. I'm thinking that I have a blown head gasket? There is no water in the oil ,or on the dip stick ,filler cap. I've replaced the water pump last year and put a new thermastat in at that time and all was good till about 2 weeks ago . What do you guys think head gasket ? I'm a car guy but the more info the better old tricks are the best tricks. Thank for the help
Don
 
Check your cap before anything.Is there any rhite smoke out of the tailpipe? most times if its putting compression in the coolant it will suck coolant in the cylinder. Mark
 
I've have no white smoke or water out the tail pipe. I checked a couple of 180 thermastats that I had on the shelf and put in a different one that was drilled and ran the car in the drive and nothing so I'm getting ready to take it out and see what happens.
 
Took the car out for a short run and it seemed to do ok .I'll flush it out and redo the antifreeze and keep my fingers crossed.
 
It's perfectly normal for pressure to build up after the engine warms up because coolant expands as heat is applied. It is also normal that if you remove a radiator cap from a hot engine to have it spew the antifreeze out so it's not a good idea at all to do so. I've seen guys get major burns doing that. If your car runs good and doesn't loose coolant you have nothing wrong. If it builds too much pressure it'll puke it out of the overflow hose/tank. That's when it's time to check things.
 
I have seen some of those cheap t-stats not work correctly...make sure you get a good one....and get a new cap too...I run a 7 lb one on my car
 
nicoles said:
I have a 66 barracuda with a 273 2bl carb. after it warms up i've noticed that I have pressure built up in the radiator .I'll take the cap off and the water boils out . I checked the water temp and it said 185 .also the gadge read normal.
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I'm just wondering.....what ever made you think there was a problem?......unless it was blowing coolant or steam out of the overflow......(?)
 
Sounds normal to me. I would burp the system just to be on the safe side, top it off then drive the wheels off.
 
fishy68 said:
It's perfectly normal for pressure to build up after the engine warms up because coolant expands as heat is applied. It is also normal that if you remove a radiator cap from a hot engine to have it spew the antifreeze out so it's not a good idea at all to do so. I've seen guys get major burns doing that. If your car runs good and doesn't loose coolant you have nothing wrong. If it builds too much pressure it'll puke it out of the overflow hose/tank. That's when it's time to check things.
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Will puke out of overflow sometimes too is normal. I agree with all. If temp gets too hot, take out thermostat and check with boiling water on stove then drop in after boiling starts. If it opens its good. All cheap thermostats suck. We have gotten 3 bad ones in a row and took them back. Pay the extra $ if you have to get one. We went back to the original brass on from 69 after CLR cleaning! Good Luck. Also you could put on aftermarket overflow bottle and you would not have to take cap off.
 
The car was blowing water and steam out the overflow tube and the gage wasn't reading all that hot. I would run about 12 -15 miles and when I would get to where I was going and park the car would puke out a bunch of antifreeze and water .I would refill it be for comming back home .This happened 3 or 4 times .before I had time to work on it. Now it seams to be doing OK .I do have a overflow bottle on the car and it filled it and still puked out a half a gal or so .Don
 
also you need to remember when running a pressure cap it will rasie the boiling point of the water so when you releave the pressure by takeing the cap off it will go right into a boil because the water temp is higher i hope i explained that all so you could understand it (not much for words here )
 
also stop adding water everytime you stop the water level will keep purging remember cold when you fill it expands when it get hot which make the over full so it purge itself then it cools and looks low but it isn't as soon as it gets hot again it will expand and be full again i hope you understand
 
proper filling of the over flow botlle is a 50/50 mix of antifreeze and water and should only be 1/4 full or just barley covering drainhole in bottom of overflow tank. As engine gets hot overflow bottle will fill and it may puke a little. When it cools the coolant will draw back into the engine and appear empty when cool. I would still shoot for bad stat first, then go for cap. Most overheat problems can be tracked to a small leak. How is your heater core? I always end up having to rplace them on all my 60's Darts. Is there fog or a smokey like skum on the winsheild that you have to clean at least once a week? Sweet smell in when the heater is on. When you are running "Hot" does running the heater change anything? Please advise.
 
Just a thought. Check your lower rad hose and look for a colapsed section that might restrict water flow. Make sure that hose has one of those long springs in it. They keep it formed to an open condition. Your rad will produce a small amount of pressure in a normal situation. Sounds like you may have had a bad T stat.
Keep us posted
Small Block
 
Some of the new hoses you buy now have the reinforcement inside the rubber and do not have the wire spring in them anymore.
 
If it were mine, I would probably install a new radiator cap (correct pressure rating for your car) and go from there.
 
I've changed the thermastat, put a new cap on. Fluched the radiator and motor.then cleaned it out before I replaced the anitfreeze .every thing seams to be running cool now ! Thanks for all the insite and help .Don
 
Like was said... these older cars were supposed to puke a little until the correct level was found. Filled to the top they will spit up when they warm up, even with no air trapped in them...lol.
 
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