Do you think Toyota would spend millions to put the same pistons & rings back in the engine? Is it worth it? That depends on the overall condition of the vehicle. Would the cost of the rebuild exceed the worth of the car?

 

Well I ask because I've seen a few videos on youtube where they say there is no visible difference between the pistons. The only difference being the construction of the oil ring. Since people claim that the defect is in the size and/or amount of oil return holes, this seems odd.

 

As @RTexasF says, they spent millions on the fix. There are new pistons, rings and oil channels (if I remember correctly), and this, as far as I can read, fixes the problems. If you are going to do it yourself, look at the TSB in detail to work out what needs to be done. If you get a shop to do it, it will be several thousands of ASD - is it worth the value of the car, only you can tell

 

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My 08 I4 engine was rebuilt with the newer designed pistons and rings a few years ago. The engine regained a little power and better fuel economy. Can't even tell if it burns oil now, if any at all.
The oil ring galleries are bigger and there is something definitely different with the pistons. If you can do the work yourself, it may be worth doing it. I think the cost at the dealership was about $5000 that I didn't have to pay.

That's very good to hear. I will be doing it myself. Since the issue won't return, I'll probably bite the bullet! I have done this sort of thing before, but it'll probably take me a few days

 

The oil rings indeed yes, and also the oil holes - it did not take much to cause the problem apparently, even with regular maintenance. I think there was something with the pistons too, but I can not remember precisely

Only you can determine if it is worth the effort

 

My 08 I4 engine was rebuilt with the newer designed pistons and rings a few years ago. The engine regained a little power and better fuel economy. Can't even tell if it burns oil now, if any at all.
The oil ring galleries are bigger and there is something definitely different with the pistons. If you can do the work yourself, it may be worth doing it. I think the cost at the dealership was about $5000 that I didn't have to pay.

 

@kevcules46 , thank you for letting us know, and glad it is sorted for you

 

Let us know how you get on

 

About the difference between the original and revised pistons, as I saw in photos the original pistons had a notch which allowed more oil to contact the oil control ring which was more than the ring could control. The revised pistons eliminated the notch.

 

That is a good piece of information, thanks for sharing

 

Is replacing the pistons and rings something a novice could do, if he follows a step by step guide? I do have a repair manual that appears to have step by step instructions but I've only done simple jobs like brakes, spark plugs, etc.

 

Not a novice type of repair, even a seasoned DIYer

 

As above, it is a difficult job - to many problems can occur if you get even one thing wrong

 

In the "good old days" when engines were much more accessible replacing pistons and rings ordinarily was not a difficult job if one had the needed tools, but with today's engines and items such as their added accessories and with FWD the situation is much more difficult. A lot of years ago in high school we did that sort of job in "hopping up" engines but I wouldn't do it now.

Also when I was in high school the school had a fully equipped auto shop which for training purposes would do all sorts of work including on engines with the only cost to the owner being for parts. Perhaps in your area there could be a school or college which does similar work.

 

The new piston and rings were a band aid fix. The 2.4 litre design was flawed and some that drove 100,000 miles on the new parts had the high oil consumption come back again. So unless you drove a lot of miles it only delayed the problem down the road. This is why Toyota ditched the 2.4 litre engine and came out with the 2.5 litre engine. Hope this clears things up.

 

Even the new pistons have problems? Really? If that's true, then I'll just get new rings and use the old pistons.

I have not done ours yet, but when I do, the oil holes are getting turned into slots....nice and big so they can't plug.
I always wondered if the piston oil squirters were partly to blame, since the oil hitting the bottom of the piston is trying to go out through the return holes. Perhaps some light porting/shaping is in order to deflect some of the oil?

ours is burning more oil and I just replaced the plugs and valve cover gasket today because the plugs were ash fouled after maybe 50,000 miles. There is some coolant missing, and I hope it's not the head gasket/bolts. I think I am going to end up rebuilding my spare motor and then just swapping them to save time. That way the motor is ready to go, I don't have to have the car down waiting for more parts, and there are no surprises. The spare has half the miles too....140,000 vs 315,000.

 

Have been here for some years and if I recall most of those 2.4 owners who had the Toyota fix (replaced pistons and piston rings) done reported that the fix solved their oil consumption problem, even after lots of miles driven on the rebuilt engines. Someone might want to do a statistical analysis . .

 

I've had the job done to my 08 and my engine acts like a new one with very little oil usage now.
If I was going into the engine that deep to replace the rings, I would certainly change the pistons as well. Toyota changed that design also, as well as the rings for good reasons I'm sure.
Investigate a little further if you like, but I would recommend changing both the pistons and rings.
I've got about 30,000 kms on the rebuild so far.
Good luck....

 

That is good to know @kevcules46

Hope you get a further 200K too

 

The Toyota fix is no fix at all.
You post is very important: this is a technical issue so I have a long response. I went as hard as possible trying to find the answer and could not find it. The cause is gumming up and blockage of the oil rings and oil drain holes.
(a) I followed all the part number changes for pistons through 2001 to 2018 trying to find the defective pistons. I have seen no side by side comparison of the defective versus "corrected" types, except one suggestion by a youtube commenter that the defective pistons have a notch under the oil ring. This notch was introduced when oil squirters were added. Many performance pistons have such notches, so it is an unlikely cause. Even the Toyota tech guy (car care nut) on you tube could not show the difference in his video on the oil problem.
(b) I followed the low tension ring story (low tension to decrease friction and improve milage). No direct comparison between standard tension and low tension rings is available. I could find no standard tension rings for the 2AZ-FE and there is no tension information on performance rings, such as Wiseco.
I followed production sites, originally thinking that only Kentucky pistons were defective. Kentucky made standard size "B" pistons but the other sizes (A, C and D) came from Japan for US made engines. These different piston sizes are not the cylinder bore size, but refer to accomodating variation in the crank manufacture to save cranks that are out of spec. 95% of pistons are B, so rare engines have a mix of types.
(c) I followed up on US-made versus Japanese, hoping that only US were defective. The oil problem happens at a low rate in all 2AZ-FE regardless of where they were made. The 1AZ-FE has the same pistons and can have the same problem, but was not included in the US TSB (a recall that is not a recall and only in the US).
(d) Oil change interval, synthetic or non-synthetic: no consistent outcome came from this investigation. Some who adhered strictly to the rules had trouble, others who abused their engines with dino oil and long intervals had no trouble. Anecdotal reports of seafoam and other additives having positive effects suffer from reporting bias.
(e) Oil drain holes: number, diameter of hole and angle of hole in piston. I have seen claims that this is part of the new design, but I cannot find a direct comparison that verifies this claim. A proper technical paper should be published if this is the case.
(f) Piston heat hypothesis: it is claimed that the 2AZ pistons run hotter than planned. Compared to the 1AZ, with more fuel, the 2AZ will produce more heat with essentially the same cooling system. The 1AZ does not have the donut oil cooler that was added to the 2AZ. I also think people drive the 2AZ differently: having driven both the 2AZ is more satisfying with the low end torque. Its more fun to lead-foot the 2AZ.
It seems convincing that the notorious head bolt problem is caused by a foam insulator between the block and the plastic intake manifold, causing excess heat. Cooling is clearly an issue. In 2006 oil squirters were introduced to aid cooling as well as an insert in the water jacket to direct the coolant differently. As far as I can tell, these inserts and squirters are absent in 1AZ and 2AZ prior to 2006. Excess heat causing oil gumming could be a cause of a sporadic problem. Toyota tech scientists should publish their data. Small defects in cooling system maintenance might be a cause.
(g) PCV valve and carbon. Oil vapour from crankcase ventilation leads to carbonising of intake valves and piston heads. A bore scope camera down the spark plug tube shows carbon on most piston heads. There is no harm and maybe great benefit from adding a catch can between the PCV valve and the intake manifold. It should have been standard. It is notable that the new 2AR-FE has a built in oil separator (basically a catch can), so Toyota agrees.

Conclusion. I eventually reached the conclusion that the Toyota fix is no fix at all. Just imagine, if you replaced the gummed up old pistons with brand new pistons of exactly the same design what would happen? The engine would be returned to normal and you would have at least 100k miles before the problem might come back. This puts you way out of warranty and one step closer to the junk yard and no longer Toyota's problem. Since I cannot find any reasonable design explanation, that should be all over the internet, this is the only sensible conclusion.

Are there super redesigned pistons? Probably not, since even Toyota wont show us the difference. If your engine is burning oil, then get new pistons. Add an aftermarket oil cooler, keep coolant levels up and get rid of any air in the cooling system.

 

I have been thinking the same thing for a while now. I thought the difference was a 3 piece oil control ring vs 2 piece.

 

All these theories are nice, but let me throw out some fact. That two peice oil ring design Toyota used , is a High performance racing piston design for motors that see oil changes every 15 hours and piston replacements every 135 hours, which avoids the oil ring cloggage issue. When you start running these oil rings more than 500 hours, cloggage starts happening.
By the way, its not the piston oil return holes that clog, its the tiny oil ring holes that clog, That notch they did away with, does nothing, as pistons with out the notch will still get a clogged oil ring with that 2 peice oil ring design once you start going over 500 hours.

 

Thank you very much for that very useful information. I did not know that the 2-piece oil ring was a racing design. That makes sense. I suppose Toyota was trying to meet ambitious mpg mandates and so used a design that the engineers must have known would clog. Care Care Nut on youtube states that the 2AR-FE avoids the problem by using thin 0W oil and a built in oil separator (catch can). The 2AR pistons look the same as the so-called defective 2AZ pistons.

 

Every vehicle made has at least one big flaw and eventually causes it to be traded off or scrapped. It drives the market and the makers know it. If there was a car that handled great, drove real nice, got real good mpg, and ran forever, they would not sell much of anything else. Toyota has oil problems, dodge has trans/electrical problems, ford has turned into crap, and chevy can't get it right for anything. I have replaced windshields on all of them, and that lets you see stuff that only the builder ever sees. The metal on the new cars is literally paper thin. I grabbed the metal that the windshield is glued to on a ford today and could have balled it up like crumpled paper. It was that thin.

There was an f350 next to it that was in for exhaust warranty. The frame looked like crap. Thin, multi-piece, and not something I would ever expect on a truck. The front arms are pretty much card stock. That truck would never hold up to any kind of truck use.

Corrosion is designed into modern vehicles. Body guys will tell you the same thing. All the new vehicles are half-assed and over priced. I replaced a windshield today that was glued to the roof at the factory. I never thought I would be able to say that, but I can. I have zero interest in a new vehicle.

I'll get some 3 piece rings and fix it myself. Screw that toyota recall/warranty crap.

 

Ike, are you chasing kids off your lawn again?
(LOL!)

 

I just did a complete rebuild on my 08 Camry LE. The difference in the pistons is just the weep holes are slightly bigger. The biggest difference is just the over kit in itself. New pistons w/ larger weep holes, upgraded rings (different compression ring style) and larger oil nozzle diameters for juicing the pistons.