Changed heater core hoses...Now Need to get air out!

[robcarync]

So I changed out both heater core hoses tonight...pretty easy...tedious though. Used a razor to get the old hoses off the fittings. Problem being that after the lowest end of the low hose popped off, a good bit of coolant was lost from the engine before I managed to get the other end of the hose on.

Seriously...I left a puddle of coolant the size of almost the entire parking space at my apartment complex...ooops.

I let the car idle a bit with the heater mode on, but (of course) the engine begin to overheat.

I know that I need to burp the system....but even after searching I couldn't quite find a clear cut explanation of what to do. I have a gallon of antifreeze 50/50 mix, but I'm not sure how to properly go about getting the air out and refilling the system...I'm pretty sure I found a good thread last night while searching but I can't freaking find it anymore...

The FSM said to use some fancy tool using pressure gages etc...commmmmon gimme some help guys!

[xtacular]

Just loosen the bolt on the top of the intake plenum- it's near where the intake tube attaches- while it idles. As soon as coolant starts coming out you're golden!

Edit: Maybe not with the engine on, not sure. I think you can do it with it off if you pump the upper rad hose. But that screw is your key to happiness.

[intender]

You will probably have to burp the system a few times to get all the air out. After I replaced my radiator it took me about 2 weeks to burp all the air out. Granted I more or less drained the whole system so I had more air in it than you will, but I would suggest checking it every few days until the air stops and then check it again in about a week. you will have at least as much air in the system as the heater core can hold if not more.

And the best time to do it in my opinion is when the car is idling after it has been driven for a while. The coolant will be hot, but the extra pressure in the system from the heat seems to help push the air out of the system easier. Just loosen the bolt up a bit until you hear the air start coming out and then be ready to crank it back down tight as soon as the coolant comes out.

[robcarync]

that the one?

So i drive the car some...let it idle...then loosen that bolt? Radiator cap and expansion tank cap still on while idling? Is it OK to loosen that bolt while the car is warm? Is it pressurized or anything?

[xtacular]

Looks different than mine... I can grab a picture tomorrow but it looks like Nissan changed the intake design at some point.

[robcarync]

it's a bolt right above a rubber hose going into the intake manifold...I assume it is a coolant hose right below it...it was the only thing that looked like part of the cooling system.

Got the temp stabilized at least now...no hot air blowing though...

[robcarync]

well that bolt was too tight...every wrench i tried just started to round the head...

but after a test drive my truck didn't over heat, and I did have heat blowing...I basically just let it idle and kept pouring coolant in the radiator....

never saw a change in level in the expansion chamber....but I have heat, no over heating of the engine, a funnel, and 1 1/2 gallons of 50/50 mix in my truck so I should be good to just drive and keep an eye on it

[irishprodigy]

I've always burped the system at the radiator cap when I filled it and never had an issue so far. Thats unusual, but if mine ever does that I will know where to look.

Oh, thread jack but if we dont get the storm it looks like we will I'll have a mod done that also looks familiar

[robcarync]

well all I did was let it idle for a while with the radiator cap off....kept pouring coolant in the top of the radiator. No leaks....no overheating...warm heat. Only thing is the level in the expansion tank didn't move one bit...I figured after the driving that level would adjust? The min and max lines are on the side of the expansion tank...how would I know when it is full? Typically, I would expect to see gargling and bubbles as coolant goes down....air comes up...didn't see that though...not in the expansion tank or in the top of the radiator.

As much as I have worked on cars before...I have always been...very awful at flushing radiators and working all the kinks out of cooling systems...

[RacerXXL]

Air relief screw location