NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10

[QUOTE=" hThe technician wrote up for the TSB and they ordered the parts.[/QUOTE]

 

welcome,

exactly!

 

I have a 2010 Prius, milage is around 140 000 km.

I got the same issue recently when moving the car and running the ICE for a short while so it was interesting to read this thread and get some ideas on what is going on.

Otherwise, I have had no major issue so far and I think HSD is a brilliant drive train.

BTW, I have an electric engine heater and cabin heater that I use most of the time during winter. Maybe that could be a tip for some.

Another thing I was thinking of. I live in Sweden and here we have E5, i.e. 5% ethanol in our gas. Ethanol is great in binding water, so I was thinking that could be a help if the problem is related to that?

Also, I would like to see anybody trying to switch the gear to neutral as soon as the ICE starts and when the problem occurs. If the saftey clutch is activated as somebody suggested, and it makes that bad noise, I think neutral would at least help with that and maybe prevent any damage to the drive train. And as neutral will help off loading the engine from charging the hybrid battery I guess it could shorten the time the ICE is not running on all four cylinders.

 

Believe it or not this knocking issue is still happening on the 2018 Rav4 hybrid. That's what I'm driving now. Toyota still hasn't fixed the underlying problem in their hybrid vehicles!

 

Oil catch can?

I’m considering the same for our 2017 RX450h.

 

I have a 2010 Prius with 95k miles that just started knocking when the ICE starts up. It has happened twice so far, both times after running the ICE very briefly (5-10 seconds while moving the car out of the garage), then letting the car sit overnight in moderately cool temperatures (35-40F), then starting it. Here's a video of the issue:

I brought it to my local Toyota dealership this morning to see if they would replace the EGR valve under warranty (I'm covered by the California Emission Warranty for 10 years/150k miles) but they're still trying to diagnose the problem and can't provide me with further info yet.

From reading threads here it seems like this is a very common problem, that the original fix (intake manifold) doesn't work, and that the real fix is to clean the EGR pipe and install an oil catch can (or alternatively just clean the EGR pipe immediately and then continue cleaning it at regular intervals). Is that correct? Really I'm just trying to figure out what to do from here - even if the dealership is willing to replace the EGR valve it sounds like that won't actually fix the issue. I have an independent Prius mechanic that does most of the work on my car and has been very helpful over the years, so I would prefer to have them work on the car rather than the dealership. The only reason I took it to the dealership in the first place was because I thought this might be covered under the California Emission Warranty, and of course I'd prefer to have it fixed for free if that's possible

Or should I just accept that this is normal on the next start after running the ICE for very short periods of time (like moving the car out of the garage) and avoid doing that? My main concern is that this could indicate a bigger problem that would require expensive repairs down the line (like a head gasket replacement).

Any advice is appreciated Thanks so much!

 

The fix is supposed to be a redesigned intake manifold which is available for the Prius. Don't know about the Rav4 though. I'll have to take it in to the dealer. It has less than 2000 miles on it so I doubt oil build up is an issue.

 

The redesigned manifold doesn’t work.

An oil catch can does.

Root around in the gen3 forums and you’ll find that the catch can stops lights from entering the combustion chamber, leading to less to no knock.

That’s what I was referring to.

 

If that's true, why does the knocking problem only happen in cold weather after the engine runs for a short time then is shut off and is cold started hours later?

Also it seems to diminish over time. I never got the manifold replaced on the Prius because the knocking happened less frequently after a few years. It seems to be worse when the engine is new.

 

The engine never gets up to temp and the condensables are there.

They get sucked into the engine and ten cause what you are referring to. The catch can is the wife spot in the line or knock out pot which prevents them from getting back into the intake manifold.

 

Are Atkinson cycle engines more susceptible to this issue? Most modern cars don't have this problem and they don't have oil catchers.

 

You sure about that?

Camaro’s come with an “oil separator”.

So they’re out there and not unique.

 

Not talking performance cars, which the Prius is not.

 

I would consider the issue "normal". If it happens again, please try switching gear to neutral directly when the ICE has started and the knocking sound occurs (then back to parking when it runs ok). Because it seems the knocking sound is actually a safe clutch engaging when one or more cylinders misfires. That is to protect MG1. But using neutral I think you will achieve the same thing, i.e. MG1 will not be enabled (and the hybrid battery will not be charged).

Starting an ICE on any car and switch it off after a short while (when the ICE is cold, especially in winter) is really bad. So is not just Prius at all. Instead HSD has the advantage that it will under normal condition cold start more easily than any other car. That is because the high voltage hybrid battery is used to start the ICE (not the 12 volt battery), and it is done using the powerfull MG1. Also the ICE will get warm faster than on conventional cars. The HSD system is not perfect though but I personally think the good easily outweights the bad. But of course it helps to know how the system works and the weak points.

 

That is not good as it really scares people when that knocking sound occurs. It sounds as if the engine is about to break. But it seems this is not a big problem, not more at least than that the engine misfires on one or more cylinders. And that could happen to any car where you have started the engine for a short while. It will get flooded with fuel I think, which will make it hard for the spark plugs next engine start.

Anyway, it would be great if somebody in this thread, once and for all, could confirm that the knocking sound stops if the neutral gear is activated. Then the theory of a saftey clutch engaging when in "P" would hold true.

Also, as on any car, never run the engine for a short while. I would say you should at least give the engine five minutes, so it gets a chance to complete the warm up cycle.

 

Could someone point to the "safety clutch" in an engine diagram? And explain how it is engaged and disengaged?

 

Yes!.....i would like to know for fact, what ACTUALLY makes the noise.......it scares the crap out of me!......I'm of the belief that you cannot bang two pieces of metal together without causing wear/damage of SOME kind!......

 

From another thread;
"The "clutch" is there as a torque limiter. It will slip in the unlikely occurrence of excessive toque stress in the drive train. There is no mechanism to disengage it, it is always engaged. "


Anyway, if the theory is correct of a "saftey clutch" engaging to protect MG1 (or stop MG1 from charging the hybrid battery), when the engine misfires, then it would be logical that you would not hear that grinding sound if you put it in Neutral gear. Normal behaviour is for the system to charge the hybrid battery directly when the engine has started and you have it in Parking. When you put it in Neutral the engine will keep running but it will stop charging the hybrid battery.

 

Thanks HSD-fan for the clarification. I was quite aware of the safety clutch in the drive train. It is just a simple mechanical pressure plate that, as stated, is there to protect the drive train. It was the "engaging" and "disengaging" statements that made me question what clutch was being discussed.

 

Ok, thanks gliderman!

Anyway, Toyota and Lexus are selling an enormous amount of HSD drivetrains today, and we are here talking about generation three of HSD. I feel that some posts here exaggerate this issue. My understanding is that the HSD drivetrain is even more durable and reliable overall than Toyotas more conventional drivetrains, and that is saying a lot! And gen3 is the first gen that is totally beltless.

Still, I am curios about switching to Neutral as a better solution, I may try to reproduce the issue soon myself, just to test that.