Q: Car heater was blowing cold air until at highway speeds, then stopped putting out any heat. Dealer says blown head gasket

asked by on

For months, car heater blew cold air until highway speed reached, then stopped putting out any heat. Dealership diagnosed blown head gasket after mechanic pressured system and found residual coolant in chamber. While saving for repair, we drove car occasionally, short trips. Heat started working again so wondering (hoping) if that indicates something other than head gasket. Car has never overheated nor has temp gauge gone high.

My car has 118700 miles.
My car has an automatic transmission.

You may have a clogged heater core which may be preventing the heater from working properly. Generally, a blown head gasket would cause the car to overheat and would eventually get worse to a point where the vehicle would no longer run. The heater core is a series of tubes that the coolant runs through that generates the heat from the warm coolant after circulating through the motor. These tubes can occasionally develop a buildup on the inner walls such that when the heater core is "flushed" this buildup on the inner walls of the lines remains and still allows the coolant to flow through the heater core. It is important to note that when the heater core is "flushed" it is possible to get good flow through the heater core while the inside walls of the heater core remain caked with buildup. As a result, the buildup on the inner walls prevents the temperature from rising to its capability due to the insulating effect of this buildup on the inner walls which will prevent the necessary heat transfer to properly heat the inside of the car. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your heater core.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Car heater was blowing cold air until at highway speeds, then stopped putting out any heat. Dealer says blown head gasket

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: What kind of modification/performance can I do to my car?

Hello - the best way to keep your Altima running like new is "attentive maintenance". Keep fluids (oil, transmission fluid, coolant) topped off and changed at recommended intervals. If your timing chain and associated components (tensioner, idler, chain guides, etc.)...

Q: Car just won't move forward or reverse.

Hi there. When your vehicle cannot move, put the transmission in park and then in drive. See if the engine is loading up and the rpm's are dropping. If they are then check the brakes and see what is causing...

Q: code is p0340 i change camshaft position sensor but still shows same code .any help or advice

Hi there: The problem with changing out the camshaft position sensor is that sometimes the issue is actually due to the sensor wiring harness; which might be the reason this OBD-II error code was triggered initially. The P-0340 trouble code...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...