2015 Prius C Two 36k miles I reside in WNY My car sat for a few days in our garage. Last I drove it was a short trip (2-3 miles) and I *think* I turned it off while the ICE was still running. Start it up today after a huge snowstorm and temp drop and I got the dreaded engine knocking for 5-7 seconds. I've read a bunch of threads and am trying to determine the next best steps: I'll watch coolant levels Wait until ICE stops to turn off the car Could I actually have a head gasket failure at 36k? ✌
All Prius by nature run rough after not being started up for a while, especially in inclement weather. It's the nature of the Atkinson Engine... Nothing to be concerned about unless it gets way worse.
1 this will cause all kinds of rattling on next start, consistently 2 yup, but it's it the engine knocking, or the planetary , +trans just raising hell ? 3 check oil, coolant, brake, etc levels at every fuel stop .. this is always a good idea 4 very good practice 5 highly unlikely, but possible of course.
You should be ok. Honestly I cannot remember my C ever starting with the knock, but in my Gen3 after the shutoff while running it knocked while restarting I think twice. As far as I can remember, it was like first or second year of owning it new, and after learning that (shutoff w/running) never happened for the next 4-5 years of owning it. I did have some funny acting in my C while really cold out 4-5 years ago, but since then I added an engine block heater and no such thing nowadays. 2014c with 55k miles
How did I drive 150000 miles in my C with frequent (daily for quite a while) visits to this forum and this is the first time I have seen it recommended to not turn the car off with the ICE running? Just a guess, but I suspect that 70% of time I have turned the car off with the engine still running. Never had a knock or any other engine issues. What's the theory behind this recommendation?
I can't remember the exact reasoning but I found a handful of threads that recommended it while searching about the engine knocking. People mentioned head gasket failure, spark plug replacement, fuel injector cleaning, and condensation on the intake manifold(?). I could be wrong but I think condensation on the intake manifold was more likely if you turned the car off while the ICE was running. Again - I'm drawing from memory here. Sounds like you've lucked out with no engine knock!
Quick update: Car sat in our garage for ~36 hours. ICE wasn't running when I turned it off. Started up this morning (13℉) and had no knock! I discussed this all with my wife and we figured that the car had sat for 5 days (previous to the knocking) without running and also while the temps dropped from 35-40℉ to close to 0℉ and during a snowstorm. I'll occasionally update this thread for posterity and in the event something pops up. We have a run of below-freezing days coming up here in WNY and I occasionally work from home, so the car could sit for a day or two. Thanks again for the help! I'm not a big car guy but damn I love this 'lil hatchback and now I get it!
