Hello, I have a Prius 2010, 300.000 kilometers, working fine. But during winter cold start, sometimes I got that shaking and knocking sound. This typical for headgasket or clogged EGR. I do have new spark plugs, EGR and all air intake manifold is cleaned same as throttle valve. With oil change I do change air filter as well. I havent noticed any coolant level drop. Coolant seems very clean, same as oil. No oil consupmtion, or if so, minimal. I do not add any oil during the interval of 15.000 kilometers. I did have the headgasket leak test (blue colour of the liquid did not change colour at all). But still, not everytime, but time to time, (mostly when battery level is low after start) I get this typical shake and rattle/knocking which is sometimes quite heavy. After some time or slight rev up it goes away... Only during cold start, after, lets say freezing or nearly freezing temperatures... Do you have any tips to solution, or if I can 100% diagnose wheter it is or it is not headgasket? PS.: I am sorry for bad english, not a native speaker
There's other reasons for rough running when cold with this type of engine (Atkinson) so as long as you aren't low on coolant you've got nothing to do worry about (for now).
thanks for the reply. Well I am new with hybrids, I do own the car from April 2023. From that time coolant dropped maybe one centimeter below FULL mark. (35.000 kilometers run from that time) I guess that is not any significant drop, is it? On and one thing more, passenger side vent blows definitely colder air than rest of the vents and the stream is also lower...? and what are the other knicking reasons with the atkinson engines during cold?
That tests specifically for exhaust leaking into coolant. 3rd Gen failures are typically coolant leaking into combustion chambers, usually starting with cylinder one, and sometimes two. Try boroscope inspection with cooling system pressurized, and/or leak down test.
Well thanks, as soon as i have time i will try to check it. But gotta get the cam amd weather has to get better but I also heard it can really be the condensation, when you shut the engine off in bad moment, is it true? Like when it is cold and did not finnish the warming up cycle or even when it is after longer drive, but at the end of travel it went on battery, so the engine got a bit colder and you drained battery. Which i remember last time it did I did have this case, 2 bars in battery meter and I shut the car off before it started engine to recharge...?
