Headgasket??????????

[speedin]

alright, a real quick run down. my sister in law borrowed my car then proceeded to over heat it and blow a hole in the radiator. i replaced the radiator and the t stat at the same time. i started it and let it idle in my driveway for a few when the reservior tank started to bubble. i assumed it was air getting in from a now blown headgasket. there is no coolant in the oil or oil in the coolant. i talked to a couple mechanics and am now confused as i got totally different answeres. mech #1 says most likely headgasket. mech #2 says probably just sensors mis-reading the temp of the coolant and it is now overheating again and not just a airflow coming in from a possible bad gasket. i am by means no mechanic but i am confident if i get some GOOD direction that i can repair it. i did not do a leak test and i am finding that i may not get a sense of what the problem is even with that test. HELP...

 

[haveahotcarl]

Your radiator will bubble no matter what if the coolant gets drained from the system. It is just trapped air in the passageways finding its way out once the coolant starts flowing. I can almost guarantee it is not bubbling from a blown head gasket. As for the "sensor issue" the other mechanic guessed...it is hard to say for certain. If the gauge is reading high right away (with a clearly cold engine), it is probably the sensor. The cooling system on an MSP in a passive mechanical system; the coolant hits a set temp and a mechanical valve opens. No sensor input needed.

As for the state of the head gasket... Overheating the engine to the point where your radiator ruptures is bad news. It could certainly cause a head to warp and/or head gasket issues (but not 100% guarantee it does every time). Your radiator cap is probably bad as well because it should have opened way before the pressure even got that high. Aside from looking for oil in the wrong places, you can also look at your exhaust. White exhaust with a distinctly sweet smell is a good sign of coolant in the cylinders.

 

[speedin]

cap was replaced with the radiator. no white exhaust at least when the car left my house although it could have during the time she had it. she had only driven it for about 15-20 miles. when the overflow bubbles the temp gauge never reads above middle (between L and H). not sure now if was really overheating now or if it was/is trapped air from replacing radiator. i tried cycling it by filling the radiator and starting the car and letting it take it as needed. it never got to that point as the overflow started to expand to the point i thought the bottle was going to burst.

 

[haveahotcarl]

The overflow should be venting to atmosphere, check that the hose isn't plugged. When you change the coolant you should fill the radiator up to the top of the filler cap and then run the engine for about 5 minutes (until t-stat opens) with the radiator cover off. This allows trapped air to escape through that opening. Then, fill it back up to the brim and put the cap on. Once that is done you can fill up the reservoir to the full mark.

If you are getting big bubbles out of the radiator fill neck with the cap off, this is normal trapped air escaping. Little bubbles that never seem to stop, that could be a head gasket.

 

[joka1]

IMO i would do a compression test- simple and cheap way to check

Rob