I just replaced my cracked OEM radiator with an aluminum Mishimoto. I also replaced the foam air filter in my Comptech Icebox with an AFE filter. After an hour of trying to bleed the air from the cooling system per the service manual with no luck, I decided to try jacking up the front end. With the radiator cap off, manifold bleed screw open and the bleed cap by the firewall removed, I started it up. Coolant spits out of the bleed screw and it looks like its working but after maybe 3 minutes, the intake starts to make a heavy drone that gets louder and bogs the engine. I shut it off just before it choked itself off and noticed the check engine light is on.

After taking it down off the jack stands, it cranked up and ran fine with no drone or bogging. There's still no heat so the air is still in the system. But now my worry is why wouldn't the car run normally while jacked up and have I hurt anything? The angle wasn't severe(jack stands on lowest setting) and the car ran for an hour beforehand on flat ground with no problem.

 

did you use the rad overflow tank? you need to have that hooked up even with an aftermarket rad. also i would just bleed the system with it level. i did mine that way and it worked fine. not sure y you jacked it up. I know you got the bleed screw by the firewall, there is also one next to the intake maniold by the throttle body. that is the one i used.

 

The overflow is hooked up but that wouldn't have anything to do with this situation. Jacking the car up gets the radiator filler tube up higher to help the air bubbles find their way out. Both bleed points were open.

But I'm not asking about getting the air out. I'm asking why the car bogged and made a terrible droning noise while running with the front end elevated about 18" and if I've possibly done any damage. Sorry if that wasn't clear.

 

I just replaced my radiator and the air intake has also started to make a droning noise, it's like a constant humming that wasn't there before.

The idle was also bogging but I cleaned the IAC valve and that seems to have fixed the bogging problem.

Does your car make the droning noise constantly now? Or just while it is jacked up and bleeding the air system?

 

The droning only started after I jacked up the front end. It was much deeper than any intake noise I've ever heard and got louder as the revs dropped, like shop vac loud.

I'm about to go make another attempt to get the air out(on level ground). Hopefully nothing blows up.

 

it's hard t tell what the problem could be so your intake is sucking in more air then it's supposed to be? and i thought the air was part of the problem as you bleed it and then it came back. it shouldn't do that.

 

Did you try removing the heater bypass rubber nipple and add fluid from there. Use a turkey baster.