The root of the oil issue

[Petrus]

Old drain holes design and the 2004- design.

[shnazzle]

Old drain holes design and the 2004- design.

Been covered quite a few times indeed but always good to see a reminder of how rubbish the original design is


Carolyn likes to drill the holes a bit wider and overlapping the groove a bit as well which seems to work rather well

[Carolyn]

The first revised piton design form Toyota had the same size holes and the same number (four) but they were moved don in the groove to overlap the lower land.

Much later on a new design was released (too late for almost all MR2s).

When modifying a piston, I add extra holes, make them bigger and overlap the bottom land.

Below is a pic of the first revision and the later revision (which I put in my MR S engine).

The year 2004 has no particular significance when it comes to 1ZZ pistons, btw.

[m1tch]

The one of the spare engines I took apart for my project, I couldn't actually see the oil holes with the rings off, had completly varnished up.

I think only the very very late engines had the new pistons - still not sure why people go for the facelift model and think its got the 'better engine'.

[shnazzle]

The one of the spare engines I took apart for my project, I couldn't actually see the oil holes with the rings off, had completly varnished up.

I think only the very very late engines had the new pistons - still not sure why people go for the facelift model and think its got the 'better engine'.

I had a whole argument on Youtube with a mechanic who worked for a Toyota garage and he was absolutely adamant that the latest pistons were available and introduced into ALL 1zz as soon as they were available (in 2002 I believe he said).

This is obviously not the case at all. Evidenced many times. 

He argued about the Toyota factory model and that things can go from design lab to factory within hours, not years and called me all things under the sun. I deleted my posts and apologised and declared him lord and master. No point arguing with the thick 

... Well, I wonder what went wrong then Unless they had already built like a million 1zz engines ready to be fitted whenever and then didn't retrofit.

[Joesson]

The first revised piton design form Toyota had the same size holes and the same number (four) but they were moved don in the groove to overlap the lower land.

Much later on a new design was released (too late for almost all MR2s).

When modifying a piston, I add extra holes, make them bigger and overlap the bottom land.

Below is a pic of the first revision and the later revision (which I put in my MR S engine).

The year 2004 has no particular significance when it comes to 1ZZ pistons, btw.

Carolyn has the know how and the equipment
I believe that machining was done on a vertical milling machine with a cutter not a drill. So for anyone thinking that they can improve the oil flow by drilling the existing  holes out to a larger diameter, don't do it. This would encroach on the "land" each side of the groove and you would then have oil getting to the parts you don't want it to.
Drilling new hole in the same relative position would likely help the oil flow situation but would need a very stable and accurate bench drill and I have doubts about that being successful.

[Carolyn]

I DID do one by hand in the bench vice, with a hand drill.

I enlarged the existing holes and added two more (one between the original holes on each side).  I then took a needle-file to them to create the notch in the land. The holes don't have to be round, you know!

Here's a pic (not pretty), but should work just fine.

Also here's the original piston>>>

[Petrus]

... Well, I wonder what went wrong then Unless they had already built like a million 1zz engines ready to be fitted whenever and then didn't retrofit.

It is most likely a case of both being correct.
Th JIT system of the Toyota factory means the engineer is correct: Évery mod is implemented on áll production just about instantly.
That does NOT mean it all ends up on the shop floor simultanuously nor instantly.
The difference between common parts production and specific car model assembly can vary significantly.
The MR is a perfect illustration as US production would have lagged significantly behind Japan production for the parts bin shared with other cars, the pistons being thé perfect example.
Next we get the distribution to the various markets from the US which agaín is slowed down according to sales numbers in the various countries.
The allotments for the various markets are extrapolations by marketing and are not persé in line with the sales for the periods.
The bottom line difference is that a customer in country x can get a car produced over a year before a customer un country y for a niche model like the MR with weird sales fluctuations per year per country.
Over here in Spain cars produced in the US, thus parts spec lagging behind Japan, early 2002 were imported in 2003 and sold sloooowly even into 2004. As such hardly any FL models were imported/sold here.
The RAV however went to the customers as fast as it could be rolled from the production line onto their driveways. The engine of the RAV having the latest parts, the MR2.... not.

Bottom line is that the MR2 production was for the Toyota factory an odd duck. For the large part is was outside of mianstream model flow. The parts shared with different models were: Any update to parts from the parts bin like pistons, would be instant but... Next we get a rubber band effect mismatch. The MR2 production line would not have ordered engines from the engine production line till the various markets needed next years cars.
So basically yes Carolyn, there would have been many thousands of Spyder sitting sómewhere waiting to be delivered, with no new ones produced till old stock was sold.
I stand corrected on the FL observation.
It is not a secret that the production had to turned down way earlier than marketing expected and that the last of the ´production line´ was not even availeble to all markets, so likely at least partly a sell off of dressed up old stock.
The engine serial numbers should be the give away, the only guide.

[Ardent]

There is a thread somewhere in here that covers this. Been a while since I've seen it, but from a foggy memory, I'm reasonably sure, there was never an outright definitive answer.
Probably for all the reasons mentioned above.

[Carolyn]

The engine serial numbers should be the give away, the only guide.

And what serial number would my 2005's engine have to have to have the improved pistons?

It would almost certainly need to be a 2006....(around the 1ZZ238..... range.)

But worry not.  If it's not using oil and it gets very regular oil changes, it will be fine.

[Ardent]

Are you based in Norway?
I know someone is, but cannot recall who.
Just your ref to temps, reads like now in a permanent state of freezing.

[Petrus]

when I received it the dip stick was showing up to full

That is one up on many; me. I had to mod the end a bit to be able even to gét a poper reading ;-)

Make sure you use sufficiently THÍN and fully syntetic only; this has the most chance of flowing through the holes.

[Beachbum957]

A good source of parts information is toyodiy.com.  Digging through the various 1ZZ engines, there appear to be only 3 piston part numbers, car manufacturing dates in parenthesis.

13101-22030 (12/1999 - 11/2001)
13101-22031 (12/2001 - 07/2002)
13101-22032 - superseded 13101-22031

Their parts list are usually correct, and based on that data, the last piston may not have been put in any MR2 engine, but would be the one you would get today as a replacement.

We bought a 2003 from a person who worked for Toyota when he bought the car new.  He was told by a factory tech rep that Toyota was aware of potential ring sticking problems, and he should only use synthetic oil. He only used Toyota synthetic, and we have used Mobil 1 since we bought it.  At 135,000 miles it uses no oil in 3,000 miles, and when we pulled the cam cover to check clearances, the valve train looked brand new with no deposits or discoloring and the clearances were perfect.  It was completely stock with pre-cats until 134,000 miles, and they were still perfect when the header was changed.