A few months ago, the upper radiator hose (original) sprang a leak. This caused the temp guage on my dash to rise because the engine was overheating.

I took it to a shop and they wanted me to pony up $800 to replace all my radiator hoses, replace the thermostat, and replace the valve cover gasket (unrelated to radiator). Since replacing the hose and thermostate seemed pretty easy, I did those myself and had them replace the valve cover gasket. I also flushed the radiator.

My car has been running fine, but I don't drive for very long distances. What I have noticed is that the coolant in the reservoir bubbles (doesn't seem to be boiling from heat) if I've driven the car for a longer time than usual...let's say 20-30 minutes. I don't notice the bubbling until I stop at my destination and can hear it. When I open the hood (engine off) to take a look, the coolant level in the reservoir is always toward the top, vast exceeding the "fill to" line. If I watch it for a minute or two, it goes back down to its normal level.

On first impression, I thought that I didn't properly "burp" the radiator after the flush. I did this by removing the radiator cap, turning on my car and letting it get to normal temperature. Then I squeezed the upper radiator hose several times. I repeated this several times. Even after going through this process, I'm having the same issue.

So what should be my next step or the most likely cause of this? Should I check the radiator cap (how?). Is the thermostat bad? Is it likely that air is getting in some other way? I never had this issue before the upper hose failed.

Thanks in advance for your help!

 

Also try burping the coolant system by squeezing the lower radiator tube.
I do suspect that because the engine overheated, the head gasket could be blown.
On the culprit piston's up stroke it could be pushing air into the coolant system causing the bubbling and high reading on the over flow tank.

 

I'm not sure at what point an engine is considered to be "overheated." The temp guage on the dash did go up but I shut off the car before it went into the red.

I hope it's not the head gasket. That looks like a pretty involved repair and I'm not sure if it's something I could do myself.

 

To test the cap requires a testing device, try replacing it?

Best method to test for a head gasket leak is called a Block Test. This tests for exhaust gases in the coolant. Can buy a test kit for $25-50. Some auto parts stores may loan them as part of their tool loaner program.

Overheated typically means into the red.

 

Unfortunalty its probably the head gasket but it does need to be verified either with the block test kit as a poster suggested or you might get a shop to stick a gas analyzer near the opening while its bubbling and that will tell you also. There are some pretty good head gasket sealers out there but don't expect it as a permanent repair although I seen cases where it lasted for years.

 

http://www.gobluedevil.com/blog/blown-head-gasket-repair-procedure/

This one is supposed to be pretty good. Make no mistake that this is not a subsitute for a proper repair but it might buy you some time. Read up on it.

 

Thanks David. I'll give it a look.

I'm not looking to pay for any serious repairs on my car at this point. I don't drive it much and was only going to keep it around another year or two. What's the risk of not getting this fixed? Air bubbles screw with coolant getting circulated properly and can cause the engine to get too hot, right?