Bubbles in the upper radiator hose

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I have been very aware about how is the cooling system is working because I am going to do a long travel with my car the next month. I have noticed that when I get home and the engine is at operating temp I can feel bubbles in the upper radiator hose (the coolant is boiling), my coolant temp gauge is as normal in the middle and my cooling fan isn´t always on in this condition, I mean the cooling fan switch turns the fan on and off, it isn´t on all the time like when the engine is really overheating. I have keeping track off the coolant levels for one week and I haven´t lost any coolant.

Are this bubbles normal? Should the coolant boil at normal engine operating temp?

I am going to do a 2nd coolant flush and put a new radiator cap anyway but I would like to know if this condition is normal.
 
New radiator cap may fix it. If the system cannot hold pressure then the water/coolant will want to boil at a lower temp than normal.
 
Bubbles in coolant is not normal and if the engine is not over-heating it usually indicates a blown head gasket.

If I were you I would be looking for another vehicle to take on your long trip next month.
 
Do you know the coolant is 50/50 mix with water?

Do you have an actual gauge that provides the temperature of the coolant in Celcius?

I agree with the possibilty of a bad radiator cap if the coolant mixture is unknown but the risk of a blown head gasket is also a real possibilty.
 
If it is over-heating and also with over-heating having bubbles in the coolant then it could either be a clogged radiator, or a water-pump that is not circulating enough coolant.

But if it is not over-heating and has bubbles in the coolant then look for a blown head gasket.
 
I don't think the problem is related to not enough flow from the water pump, because the temp gauge will be higher and the cooling fan would be on all the time.
 
Another vote for a cap. If that doesn't fix it, the increase in pressure may make the trouble worse enough to make the diagnosis easy. Carry a few gallons of water and pay attention to what the engine sounds and smells like. If the coolant is mixing with the oil, that is bad. But if the oil is clear, all you need is to carry enough water. This is a manageable trouble, but you have to pay attention
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Agree with coolant cap. There are hot spots in the engine that will boil coolant if there is no pressure. Its possible you are not working the car hard enough to overheat it but this condition will usually lead to overheating.
 
Odds are it is the radiator cap, but it could also be the head gasket. I've seen replaced head gaskets fail in less than a year. I would pressure test the cooling system and test the radiator cap as well, and go from there. There's nothing wrong with playing it safe, especially in a case where the head gasket was replaced.
 
Originally Posted By: JimPghPA
Bubbles in coolant is not normal and if the engine is not over-heating it usually indicates a blown head gasket.

If I were you I would be looking for another vehicle to take on your long trip next month.


+1 That being said I would check the oil and coolant and possibly sending a sample to have it tested. Only way to be sure. Otherwise I would replace the cap and try burping the system of any air.
 
There aren´t any traces of oil in the coolant or traces of coolant in the oil, and I´m not loosing any coolant. Today I will put the new radiator cap and see
 
Originally Posted By: Bgallagher
Originally Posted By: JimPghPA
Bubbles in coolant is not normal and if the engine is not over-heating it usually indicates a blown head gasket.

If I were you I would be looking for another vehicle to take on your long trip next month.


+1 That being said I would check the oil and coolant and possibly sending a sample to have it tested. Only way to be sure. Otherwise I would replace the cap and try burping the system of any air.


Pressure testing will tell you in a matter of minutes if the HG is bad or not.
 
Originally Posted By: demarpaint
Originally Posted By: Bgallagher
Originally Posted By: JimPghPA
Bubbles in coolant is not normal and if the engine is not over-heating it usually indicates a blown head gasket.

If I were you I would be looking for another vehicle to take on your long trip next month.


+1 That being said I would check the oil and coolant and possibly sending a sample to have it tested. Only way to be sure. Otherwise I would replace the cap and try burping the system of any air.


Pressure testing will tell you in a matter of minutes if the HG is bad or not.


True but I always preferred to have it sent out and see just how much if any is being contaminated.
 
Yesterday I put the new radiator cap on the car, the upper radiator hose now feels more solid, I think that it is because it is holding more pressure than the older cap, just like it should. I also noticed that the A/C Condenser Cooling Fan wasn´t turning on, it turn out to be a dirty connector and soaking both ends of the plug in alcohol was enough to fix the problem. That may also been the cause of the boilover.

On the other side the supposedly OEM Genuine Radiator Cap turn out to be counterfeit product (this happens all the time in Venezuela), so it´s leaking in the upper seal because it´s fitting loosely. I will try to bend the lids that hold the cap to the radiator to see if I able to make it fit properly, or in the worst case put the seal of my old radiator cap in conjunction with the seal of this cap so it can seal. The good part is that it only leaks when the coolant is going to the overflow tank, but I know that it is very important to get it fixed.
 
Originally Posted By: Bgallagher
Originally Posted By: demarpaint
Originally Posted By: Bgallagher
Originally Posted By: JimPghPA
Bubbles in coolant is not normal and if the engine is not over-heating it usually indicates a blown head gasket.

If I were you I would be looking for another vehicle to take on your long trip next month.


+1 That being said I would check the oil and coolant and possibly sending a sample to have it tested. Only way to be sure. Otherwise I would replace the cap and try burping the system of any air.


Pressure testing will tell you in a matter of minutes if the HG is bad or not.


True but I always preferred to have it sent out and see just how much if any is being contaminated.


I have no problem with that, I just like to know if I have a bad head gasket now rather than a week or two later. You can also have a head gasket leaking externally and it isn't going to show up in the oil. Over the years I found the pressure tester makes finding difficult to find coolant leaks very easy, another perk. Again there's nothing wrong with a UOA.
 
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