Recurring Engine Clank and Coolant Sound Behind Dash Screen

[Drew89]

So I have a 14 Edge SEL 3.5 FWD, my issue is that when idling with the heat ON, no matter if the engine is warm or cold, every 32-42 seconds, the engine will sort of jump making a sort of clunk noise causing the revs to slightly increase and come back down. It could do it as I'm driving as well, but theres really no way for me to tell. The sound is as if you have worn motor mounts and you accelerated quickly from a red light, you get that unpleasant pop/bang. Every time that happens, it's followed by a liquid sloshing/gurgling sound that comes from behind the screen on the dash, which usually lasts 2 seconds.

 

If I turn off the power to the heat controls, the liquid noise and engine bang goes away. I have no clue if it happens when the A/C is on as its winter here in Canada and I haven't tried it yet. I don't believe it's the a/c sloshing/drain issue as this is with heat on, and the engine makes the bang/revs raise which I haven't heard of anyone else experiencing.

 

I did a coolant drain and fill (3 times) back in July. My only guess can be air somehow in the system, but would that be enough of a factor to cause the engine to make that noise/ behave that way? My coolant level has been consistently in the same correct level since the drain and fill.

 

Any help is greatly appreciated.

Edited January 17, 2021 by Drew89

[enigma-2]

I'd recommend checking for codes.

 

My initial guess, based on the reoccurring frequency and related to heat on, is the a/c compressor is kicking on/off and doesn't have time to unload (there's liquid in the compressor).

 

As an experiment, try pulling the fuse for the compressor and see if it still occurs.

[Drew89]

I checked for codes, there are none. I followed a youtube video for bleeding air from coolant system (Fordtechmakuloo I think its called). This morning it seems to be fine, lots of opening/closing sounds now from behind dash, but I believe your theory is right, it has something to do with the a/c compressor always coming on/off. 

 

I am afraid to even change the heat vent setting as I dont want to cause it to start again, I will check the fuse next chance I get.

[lildisco]

sounds like your A/C drain tube is clogged.  Had this happen on my In-Laws CX9 a few years ago.  I'm not exactly sure where it's at on the Edge, but On the CX9, it was on the passenger side, by the exhaust, behind the heat shield.  All you need to do is to stick up something kinda hard, but some what flexible to stick up the drain tube & clear the blockage OR used some compressed air & blow up the tube.