Loud ticking, battery only charges halfway, with slightly elevated coolant temp.

A few days ago, my 2008 Prius developed a loud ticking sound, which is apparently coming from the gas engine as it only appears when the gas engine is running. Around the same time, I noticed the hybrid battery wouldn't charge more than halfway, no matter what driving pattern I used. I also notices engine coolant temp was a bit high.

Normally, engine coolant temp rarely goes over 190 for any reason. But I since the ticking, it has started floating a bit high when at a stop, with or without the gas engine operating. It's not much, with 199 being the highest reading I have registered, but that is still unusual in my experience.

Otherwise, the car still drives mostly normal. No indicator light of any sort. My OBDII reader is a super simple thing, but it registers no codes.

Has anyone encountered this before, or have any ideas what it might be?

 

What was a misfire like on yours? I'm not really sure what a misfire would feel like on my Prius. My only experience with misfires are on previous vehicles, usually with much larger engines. On those cars, misfires really seem to shake things and were hard to miss. The Prius right now is a bit rough, but nothing like I am accustomed to in a misfire scenario. Also, no misfire code.

This is an excellent suggestion though. It could very well be ignition related. Probably worth a compression check too, if the plugs and coils check out.

It's possible, but I don't think so. The hybrid battery was replaced one year ago, with a new unit, and the issue started almost exactly as the loud ticking sound appeared, with no symptoms at all leading up to it. As for the coolant, the reservoir is fine, but I haven't checked inside the radiator yet. Every time I think to do it, the coolant is too hot.

I didn't know there was such a thing. Thank you for the suggestion.

I did have my Toyota dealership look at it. They thought it was a main bearing. Maybe they are right. But I have a feeling they missed something. I am lucky in that I have a dealership does good work, but they can be hit and miss on the diagnosis side of things sometimes.

Oil starvation has not been a problem during my tenure with the engine, but it was a used engine put in about five years ago. And while it has been a trooper these last five years, I have never had the impression that it was well maintained by the previous operator. So yes, a worn down engine is definitely on the short list of possible problems. However, the last 6 months or so, it has performed better than it ever has since I took possession of it. So it would surprise me a little if turned out to be a worn engine. But it is certainly on the table.

The belt is still on there. It was replaced one year ago, so I am sure it's fine. I will try to get a good recording of the ticking as soon as time permits.