Hi, my car started overheating the other weekend and I had to replace a radiator fan motor (passenger side). I lost a little coolant when the car got hot the first time, and now I am still overheating when I drive around. I burped the coolant system once but might not have been thorough enough. Do I have air in my system or should I be worried about a blown head gasket? Has anybody blown a head gasket or warped a head?

 

I'm sure many people have pegged the thermometer and blown a head gasket or warped a head. Check out a leakdown test, basically you're screwing a air compressor fitting into the spark plug hole, rotate piston to TDC, put in air, check for bubbles at the radiator. There's a few more steps as well so Google it. Coolant dye works too, milky colored oil is a dead givaway.

If you're still overheating after working out the bubbles then your thermostat might be toast, radiator as well. Pretty basic mechanical system with a few simple components.

 

The chances of blowing a head gasket are minuscule so no need to worry.

I'd recommend bleeding again. Try this method:

Car cold
top off overflow tank
Jack up front end so radiator fill is highest point and radiator is at an angle to promote bubbles rising out of the fill neck
Buy funnel with taper on it. Cut funnel so you can tap it into the radiator fill cap and it will stay there/not leak as you fill it up higher than the radiator. (Or buy a lisle spill free funnel if you have time for amazon shipping). This is the secret
Fill radiator and funnel almost to top (distilled water or nissan coolant mix)
Squeeze lower and upper radiator hoses repeatedly to agitate the air bubbles out. Start with lower then upper and repeat. Fill funnel as necessary.
Start car with heater on 90 degrees but fan speed down low
Continue squeezing radiator hoses as it warms up for first 1 minute. You will see more air come out now that engine is running. Remember start at lower radiator hose.
rev engine quick a few times to about 3000rpm to agitate fluid in engine block
revisit and squeeze radiator hoses some more
Run car until radiator fans kick on. Don't run it much past this with the radiator open or it will suck a lot of coolant from your overflow when it cools down since the fluid is expanding at this point. I'd say 3-5 mins if it's warm outside.
Squeeze around some more and fill funnel as necessary
turn car off
remove funnel
top off radiator once more, don't squeeze around this time or you could suck air in
install radiator cap
verify overflow still full
drop car
start car
idle until radiator fans kick on
rev engine once more a bit
Verify that pressure is building in coolant system by squeezing upper radiator hose. You should not be able to flatten it completely
crack bleeder on passenger side, might get one last bit of air

DONE

Check overflow the next morning and top off if necessary.

It's a pain in the butt. is this process NECESSARY? No. Does it make things easier? Yes.

If this doesn't work let us know and we'll take it from there. I wouldn't get into a leakdown test just yet, plenty of easier ways to diag without compromise for now.

 

I printed out these instructions and keep them in a plastic bag in my new no spill funnel in case I need to do this again. Good stuff thanks!

 

Hey that's awesome man!

So it worked?

 

It worked perfectly.

 

I usually do all of the above and an additional final step, I wouldn't recommend doing unless you're familiar with working on cars.

After feeling the hoses and seeing they are within within similar temps or not too far off, I usually will still have cold air in the cabin. I take the car out for a drive on the freeway and go at highway speeds for a few minutes. It will get those last few remaining bubbles out of the heater core that can be a real PITA to get out sitting in your driveway.

I've done cooling on Toyota, Volvo, Audi, and my Infiniti is the only one that causes me grief...

*I did purchases an AirLift recently though, but haven't had to use it yet. It uses an air compressor and venturi affect to refill the coolant system.

 

I am very familiar with auto service in general, I worked as a technician in my early 20's. When I originally installed my motor last year I was able to easily bleed all the air out of my system without the no spill funnel. I was worried about my car overheating because it was getting hot very fast and it appeared that the radiator was full when cold. I have a pathfinder mod done to my motor and was loosing coolant very slowly through that and it was evaporating on the hot motor with no telltale signs of a leak. I will be resealing that whole ***** of an assembly this weekend.