Head Gasket?

[brody302V8]

Hello all,
My 2000 Ford Explorer is having an issue. Recently I had a shop put in a heater core last year, I dont drive this car that much. Since then I have noticed bubbles in the reservoir, however I was thinking there was probably just alot of air in the system from them replacing the core. That has been about 3000 miles ago and there are still air bubbles in the reservoir. My first thought was a head gasket, but there are no other symptoms. It is not overheating, not steaming out the tailpipe, not losing coolant, and no oil contamination, the engine seems to run just fine. I also bled the system, taking the cap off and letting the engine run until the thermostat opened. This truck was my grandmothers that she bought new in 2000, and has about 170,000 miles with the 5.0 V8.

 

[410Fortune]

5.0 not known for head gasket issues but anything is possible

No loss of coolant and still
Bubbles indicates one o two things

Blown head gasket allowing combustion gasses into the cooling system
Or
An air leak in cooling system

I would pull spark plugs and have a look, any of them look washed? Like steam cleaned

 

[brody302V8]

5.0 not known for head gasket issues but anything is possible

No loss of coolant and still
Bubbles indicates one o two things

Blown head gasket allowing combustion gasses into the cooling system
Or
An air leak in cooling system

I would pull spark plugs and have a look, any of them look washed? Like steam cleaned

Okay, I will check the plugs, how would air leak into the cooling system other than a head gasket?

 

[wollimann]

If there is a head gasket issue then you should be able to smell the exhaust gases.
There are C02 tester on the market which detects exhaust gas in coolant.
If the water cools down, maybe the vacuum sucks air through the radiator cap
insted of sucking water from the reservoir. Just an idea...

 

[410Fortune]

An external air leak with no loss of
Coolant is pretty much not gonna happen so usually when you have air bubbles in the coolant we know where it’s coming from

That is assuming that all air or purged from the system during initial burp of the system
And the thermostat

The radiator Cap And heater hoses are the highest point of the system this is really the only Place air can enter without coolant leaking out, but not likely since the system is pressurized to at least 13-16 psi

You can rent a coolant pressure tested to check for leaks

But head gasket is highly suspect if the bubbles continue to good idea to test
Coolant for combustion gasses