Loud clunk and loud engine noise in HV mode

I had exactly the same experience a few times when the car was not used in HV mode for a while. Now I use HV a few minutes every week and it hasn’t happened again.

 

I can’t recall having heard that, based upon your description, although I too comparatively rarely use HV mode.

The only really ... disconcerting ... noise I’ve heard, very roughly along those lines, is (I’m pretty sure) from the traction-control system. It happens when I take off a little fast around a tight right-turn bend. It’s hard to describe, but it’s more or less a simultaneous clack and crunch sort of sound. Reasonably loud. It’s not repeating like the sound you’d expect to hear from a bad CV joint.

Presumably that happens in hybrid mode too, although I can’t recall having heard it, again since I mostly drive in EV mode. So anyway, I can’t comment upon whether the engine sound changes afterward, but probably not.

Anyway, it might be worthwhile to file a warranty claim, although maybe not immediately. Reasonable of you to ask around for some data.

 

I have noted that a cold HV start is always more noticeable when stopped than when moving. When the engine starts it runs for at least 3 minutes to warm up, and the engine sounds very loud compared to EV mode, particularly when stopped.

What you describe appears normal.

 

...especially when you equate that loud clunk to the vent for the radiator opening.

 

Which vent would be opening at engine start?

 

The only vent that opens & closes feeds everything for the engine compartment. (And it really doesn't ever close entirely.) It's primary purpose is for heat retention. But if the engine needs to breath more during the startup process, opening for that seems quite reasonable. After all, you fan a fire to get the flames up.

 

I believe the shutter vents open in response to a need for cooling, not for engine air intake. You would want as little cooling as possible during engine warmup.

 

Generically, yes. But the car knows when it is stationary no air will be pushed through. And we know for a fact the shut doesn't take place until driving begins.

 

Perhaps @Elektroingenieur will have some information from the technical manuals regarding the grille shutter operation.

 

My anecdotal observations (never bothered to actually measure) is the shutter close occurs at either by a speed or time trigger. It's fairly consistent when leaving both home and the coffeeshop in EV mode.

 

I just put it in HV mode until the engine starts then switch back to EV mode. The engine will run for 3 minutes or so depending on the outside temp. Longer in winter shorter in summer. Doing so kills your ECO Scoreboard Fuel Consumption MPG but I’ve long since stopped concerning myself with that.