Valve lifter ticking

In older, more traditional engines, option 1 was pretty easy. You could just take off the oil pan and the crankshaft and rod ends were right there, you could even hear of leaving the crank in place, rolling out an old bearing half and rolling the new one in.

The 1NZ engine with its two-piece bottom is nothing like that. The small stamped "oil pan no. 2" that you can take off easily doesn't give you the access you need, and the "oil pan no. 1" aluminum casting that needs to be removed is bolted both to the block and to the transaxle, and its seal to the block is with FIPG, and the semicircular opening at the back is one half of the rear main seal bore, so of course you have to drive in a new seal after reassembly, which means the flywheel must be off and you need room to work there.

I have trouble picturing any practical way to do the bearings with the engine in the car.

Another thing I was surprised to learn is how small the specified bearing clearances are. They are below the accurate range for the two usual colors of Plastigauge that are easy to find; they are right in the range for PL-X, which seems to be more common in motorcycle shops, and isn't as widely sold.

-Chap

 

Yes, thanks everybody this helps me

Posted via the PriusChat mobile app.

 

OK guys, I see a lot of folks have had the Prius Tick problem and a lot has been said about it, most of which seems to be speculation. About a year ago, my 2007 Prius joined the Toyota Tickers Club. Like many of you, I immediately thought valve lifter adj. I listened with my mechanics stethoscope but could not pinpoint where the noise was emanating from. I really don't want to embark on this kind of adjustment procedure if I'm not certain it needs it. I did this procedure on my old Saab 99, and it was not fun or cheap. One thing I've noticed that no one here has said anything about is that the ticking noise occasionally goes away, usually just before the engine shuts down. This leads me to suspect that it is not anything worn or stretched in the valvetrain even though it certainly sounds like it. It can't be anything too serious because it's been doing this for many thousands of miles now, but I'd like to figure it out and fix it. So if any of you have been through this already, I'd really appreciate a nudge in the right direction.

 

A sticking VVT solenoid or a clogged VVT filter is all that comes immediately to mind.

 

Thanks dolj. My VVT valve is a new OEM unit, replaced about 1 year ago for just this reason, and it made no difference. Also, I inspected the filter screen and it was spotlessly clean. A few days ago I was topping off my A/C refrigerant and noticed that when I switched on the A/C the ticking noise went away for about 5 seconds, then came back. It came and went about every 5 seconds for quite some time, all the while at idle speed. When it wasn't ticking it sounded perfectly normal, but when it is ticking, it sounds like the squirrels are trying to beat their way out with little pick axes.

In an unrelated note, I think, but then one never really knows what's related to what with these cars, every now and then I have been hearing a ree-raw-ree-raw-ree-raw noise. Well this was not alarming since this car has made more strange noises than a alien spacecraft. I finally went after it and discovered it was the coolant flow control valve oscillating back and fourth with roughly a one second period. This could explain why I replaced it twice now. I did an autopsy on the last one and discovered that the feedback potentiometer had failed. I'm not certain if the oscillating was the cause, but it only lasted about a year and a half. Is this normal operation for this valve or is my car an epileptic?

 

That could be an important observation. Have you checked for those?

The potentiometer goes flaky first. So it sends back to the ECM a jumpy signal for what the valve position is, and the ECM of course wants the valve to be in one position, so it keeps sending opposite motor voltages back to the valve trying to get the position back where it wants.

This seems to be the main reason coolant control valves get changed out in Gen 2. Actual mechanical failures of the valve or motor are a distant minority. It's usually that pot.

Gen 2 actuators in the HVAC use potentiometer position sensing the same way, so if you ever hear what sounds like rhythmically-minded mice trying to escape from the dash, it'll be the same kind of thing happening.

Be thankful you don't have a Gen 1, which also used pots in the accelerator pedal (see: Big Hand Syndrome) and in the steering torque sensor (see: steering wheel shakes like wet dog).

 

Thanks for bringing this into focus Chapman. I actually did go a little further into the examination and discovered that the center pin on the pot lost continuity to the wiper ring and the cheap molded construction meant there was no way to repair it. Any attempt would destroy it. Any replacement pot must fit into the rather small and exacting space molded into the valve assembly, and finding that exact pot is proving difficult. I did find this panel mount version for $2.37 or 10 for $20.80 Since the one used in the valve is not a panel mount, one would need to push out the rivets and swap the green portion onto the old shaft assembly, but it's not difficult. It beats $100 for a new valve.

 

In my quest to solve the infamous Prius tick, I went at it again today. It is starting to look like dolj's last post in this thread has come closest to the mark. My gen 2 is now at 210,000 miles and has been ticking like a sewing machine for the last year and a half. I would think if it was something really serious it would have self destructed by now. My fuel economy has been around 34mpg average.

This morning I put a 45 degree PVC elbow between the air filter assembly and the throttle body to allow access to the injector connectors while running the engine. I put the car in Maintenance mode, ran the engine and unplugged each injector one at a time to deactivate each cylinder. The ticking did not stop. The fact that the frequency of the tick is half the crank speed pretty much places the origin in the valvetrain. I then unplugged the VVT valve and the tone of the tick changed as well as the rpm's. I repeatedly connected and disconnected the VVT valve and the ticking stopped while at idle but came back with much less intensity during throttle up. My engine has dark oil residue visible through the filler cap so I am now suspecting an obstruction in an oil passage of the VVT circuit. Engine ticking is listed as a symptom of VVT problems for all cars with it. If this turns out to be the cause, a thorough cleaning of the VVT system may do the trick. That means removing the valve/cam cover and possibly the VVT drive sprocket. Thoughts anyone?

 

If you've seen that listed in more than one place, which place had the best explanation for how that would be?

As I understand it, the VVT's job is to change the rotation angle between the cam sprocket and the cam shaft.

I get how that would change the precise timing of the ticks relative to crankshaft position, but more than that I'm not sure I see.

 

None offered an explanation, but my own observations were that the tick disappeared when I manually cycled the VVT control valve. That's pretty conclusive in itself. Also, last month when I recharged the A/C the tick came and went with a period of about 10 seconds starting as soon as I engaged the A/C. I suspect that the computer raised the engine throttle and changed the VVT in response to the load the A/C compressor applied as it cycled until the refrigerant charge was adequate for continuous operation.

The ticking has disappeared occasionally but has always returned before very long, also my fuel economy bounces from 42-48 mpg average to 24-34mpg, most of the time being the latter.

I am hoping that the VVT is just sticky and I will be able to loosen it up. I am wondering if there is an internal engine cleaner that is safe for use in these tight tolerance engines. I have been using Mobile1 5w30 and have a fresh change in it now. I'm considering a cleaner/flush when I return from an upcoming run to Orlando. Any product suggestions that are known to be safe for a Prius engine?

 

Update: Since no one seemed to have a definitive answer for this problem. I decided to ignore it and if the engine g'norked, I'd just replace it. Well it's been over 2 years and more than 15,000 miles. I would think that if it was anything mechanical, I'd have a new engine by now. Recently I started thinking "exhaust leak" but haven't taken the time to investigate yet since it still goes. However, a few months ago I was in the parking lot of a Publix supermarket in Florida when a cute blonde haired gal altered her course to the store's front door to come tell me to "put some oil in that damn thing!". So now that I'm back in Michigan, I went at it again thinking exhaust leak.

A couple hours later;

Well. I just crawled out from under and found no exhaust leaks and a nice clean, nearly rust free exhaust header. I put the car in maintenance mode and ran it while I listened to everywhere I could reach with my mechanics stethoscope. The tick seems to be coming from everywhere and definitely gets louder when load is increased, as in going from neutral to drive. I then removed the air cleaner and reconnected it with the PVC 45 deg elbow again so the MAF would still work. Then, with the engine idling, and ticking, I unplugged the injectors one at a time again, and low and behold, when I got to cyl #3, the ticking stopped. I plugged the connector back in the tick came back. I repeated this multiple times with identical results. This is a classic indicator of piston slap. Yes, I know no one wanted to hear that. The almighty Toyota succumbing to piston slap. So it's not only the junky Jeeps and failing Fords whose pistons slap harder than the world's best bass players. The good news is, most engines will slap for a long time, like my Ford 302 did.

Worst case scenario for the future, the piston crumbles and the rod reconditions the cylinder. Then here comes the junkyard engine. I had that happen in a Ford 300 straight 6. I replaced it with a Chrysler 400 v8. Ah, the good ole days when we didn't need 50 mpg.

I do have a bigger problem revisiting me, my New Prius Battery is not cutting the mustard any longer. It was half the price and it lasted roughly half the life of an OEM. I'm still using it but I have an old cell phone with Torque Pro permanently hanging on the storage compartment door under the radio so I can reset the Hybrid Battery OBD codes on the fly to keep it out of limp mode. It doesn't happen much while running at highway speeds, but as soon as I slow down they pop one after another. Aggravating, because it happens most when in traffic. It's a solid rust free Florida car so I'd hate to junk it. I'm back in Michigan and looking for a used pack from a wrecked or rusted northern gen 3, any tips are appreciated.

 

How many years and months old is it? (Our OEM battery is still working at 16 years, albeit with much less capacity.)
What does Dr. Prius or Techstream indicate is wrong with it?
Probably best to start a new thread on that.

(I never thought the NPB's would last long due to previous unhappy experience with Chinese NiMH cylindrical cells.)

 

I didn't use Dr. Prius or Techstream, just Torque Pro. I have balanced the pack a few times, and that helped, but it didn't last long. I also load tested the modules and have had a couple of them do a solid nosedive. Thankfully Nick sent me a couple new modules. That's the only reason I can still use this pack at all. These were supposed to be premium quality Chinese batteries. Well, I knew it was a gamble going in.