Noisy startup? (55k miles) 2018 prime

You're overanalyzing it. The ICE makes a lot of racket when cold and when working hard. It also jerks the car if it starts when you are stationary. I imagine it's especially noticeable in the Prime where you spend a lot of time in smooth and silent EV mode.

 

some the earlier years of Gen 4’s (2016-2022) have had coolant leaks in the exhaust heat recovery system. May or may not be a factor, but worth checking. Engine coolant level in reservoir is stable? Just note where it is, cold, then check again, say in a month.

 

congrats and welcome! all the best

 

Exh cam phaser set to send flames to b1s1 air:fuel ratio sensor triggering closed loop sooner. Normal operation. You're listening to raw flames shoot out the exh valves. Camry and rav4 do it too

 

If the engine has been off for a long time there may be a second or two of dry start as the oil fills the galleries to the moving parts. If yours has the cartridge oil filter, from my short experiences, some aftermarket oil filters do not align correctly on the center tube. I would stick with a Toyota filter carefully installed. My Prime is very quiet as the engine starts and stops, no vibration, no big engine noises. I find it to be a pretty quiet engine. On the highway, cruising, the engine is going on and off frequently and imperceptibly. I wouldn’t notice except for the screen icons showing the engine going on and off. I don’t put any sound on when driving.

 

The 2018s use a "normal" non-cartridge oil filter.

The engine on my 2018 definitely rattles a bit on startup, but after warmup its reasonably quiet. Definitely no ticking noises - if this is happening while the car is moving, its possible the brakes may be dragging a little. Just apply them a few times and it should go away.

If you hear ticking noises while the vehicle is stationary and the engine is running that is another story.

 

Cars are under stricter emission regulations than motorbikes. Most(all?) cars run the engine at a higher idle on start up to warm itself, and the catalytic converter, up to reduce the start up spike in emissions from a cold start up as soon as possible. That will make usual engine noises more pronounced even without considering noises that are start up only

0w16 viscosity is actually really close to 0w20 that most other cars use. Maybe motorbike oil is thicker, but the numbers on the label are specification numbers. Beyond higher being thicker, they aren't reflective of actual viscosity measurements. A 75w90 gear oil can have the same viscosity as a 10w40 motor oil. The different operating environments require different properties elsewhere. Since adding gear oil to an engine can be very bad, the SAE went with label numbers far apart to reduce such errors.

 

Have you tried different oil filters? I don’t seem to hear any startup rattle on the one I have now, except when the engine wasn’t used for about two months. The first Prime I had seemed more prone to it, and I “feel” it was worse after the N1 was installed.
Looking at the oil filter adapter there is an in and out port that goes to the oil filter. When the engine is turned off all the oil galleries are full. If there is any leakage at the filter anti drain valve the galleries will empty. But it seems when the emptying reaches the levels of the adapter in out holes the oil would stop draining. Maybe the chain tensioner drains and there is noise until it is pressurized again. That wouldn’t be so harmful like the engine bearings. I don’t know if siphoning could occur through the oil pump to oil filter. It’s pretty complicated.
I’m defining start up rattle as like one second.

Using Wendells excellent links references in his posts, he shows pictures of the oil filter adapter mounted. The lower pipe would be the inlet to the filter. The higher pipe is from the filter center tube up into the engine. So if the oil does drain to the lower pipe seeking a common level, it looks like the main bearings would drain. But it would have to drain down through the oil pump. Toyota filters seem to have excellent anti drain valves, but that’s by looking at them.
The oil filter adapter is much better than on my 96 where a single oring inside the adapter separates the in from the out sides. There is virtually no way for this to happen with the two separate orings on the Prius filter adapter. But it could leak out of the adapter which us easy to see.
Whew, my goal in this is to not have any start up rattle in the Prime as it does go periods of no engine use. I would say the anti drain valve in the filter is key.

 

@Mr.Vanvandenburg - I would be cautious about introducing any types of adapters where the engine oil is concerned. One leak and it could be a very expensive repair. The last quote I received for engine replacement on my 2017 after the oil pan was punctured was north of $20k.

 

The oil filter adapter I’m talking about is what comes on the car from the factory. The anti drainback valve in the oil filter stops the oil from draining down. If oil drains down there can be start up rattle until the oil gets back up in the engine.
See the posts on oil filter conversion for pictures of the adapter.

 

It took it more as a warning about doing after the car was made. Factory parts can still be installed wrong with leaks.

 

Does the Prime have variable exhaust cam timing? My Gen 3 can only vary the intake.

But I think it does use late ignition timing during early warmup for a similar effect.

 

Depending how your Prime was driven the last 4 winters, it's possible that the EV to HV switch over never settled down. Other owners, including me, have noticed that the engine switch on from EV mode can be rough, especially if the engine is under load during the switch over. Without the full history of the Prime, it's not going to be easy to pin down exactly what you are noticing and if it's related to how the car was driven the last 4 winters, but yes engine shake in the EV to HV switch over is real. It most noticeable when there is no EV range left and the engine has to do all the work of moving the car while it's in the warm up cycle.

 

Yes