Getting to the bottom of oil control rings

[Carolyn]

I just love my little MR S.  Having lavished various bits on her (leather seats, front spots, chain and belt tensioners , all-round brake overhaul, face-lift rear wheels and new tyres.....), I was a a little miffed to find she uses oil (far too much) when driven hard.  This car exists to be driven hard.
As a long time mechanic and engineer, I knew I just could not live with serious oil consumption, it's just plain offensive.
I've read all the stuff on 'oval bore's, pre-cats and oil-control rings, and done some research amongst knowledgeable (professional) colleagues.
Let's first look at symptoms.  There are few to none when the car is driven.  No smoke, good performance and a blast to drive.  Ok, do a compression check.  190 psi across all four cylinders, so no problems with the bores. (No way all the bores would be equally oval or giving 5psi above manufacturer's ideal top pressure).
BUT... this is an engine with 80,000 miles on it and it's 13 years old.  The compression should not be that high.  One should be just as suspicious of high compression readings as low ones.
"I've got really good compression" can mean... the compression pressure is just to high for a healthy engine.
This engine has a decat exhaust that has been on there a long time and has really good power, so it's not pre-cat damaged.  What is does have is a manufacture date of 2002.
So why the high compression?  Wet rings - a result of the oil control rings not doing their job.
My colleagues also said that, apart from problems with the piston design, the original oil control rings lacked the tension needed to do a proper job over time.  Worse... there is a fundamental design flaw in other oil-ways in the early 1ZZ.
I could rebuild the engine...parts.gaskets,,, timing gear (silly not to do it) add up to quite a few hundreds of £s, many woman-hours of graft and my toy off the road for quite a while.
Solution... buy a low mileage 2005 engine. swap all the new bits from the old engine to the replacement one, and swap out the engines. I was very lucky to find one for $420.  I had considered a 2ZZ, but I just won't use the high-end power very much and she's a JDM, TRD loaded original... So I decided to stick with the 140 bhp motor.
As this car is a keeper, I'm taking the opportunity to do all the little detailed bits that a commercial engine swapper wouldn't do, like sealing and painting the cross-member, cleaning the engine compartment, straightening out a couple of bent body parts and making her sweet for the next few years.
Now replacing drive shaft boots and she can go back together...

[Ardent]

Please keep us updated.
Will be good to know what you find regards the piston rings once you have stripped it down.

[Carolyn]

I hadn't intended to bother with doing anything to the old one.  On second thoughts, I'll put it up on the engine stand and dismantle over the next few weeks (low priority..).
No doubt I'll end up feeding it some new parts and putting it back together.  I'm sure somebody can use a good 1ZZ.....

[1979scotte]

It always nice to have members with real practical knowledge.
Keep up the good work.

its so interesting to hear you say that the compression is too good for an old engine.
First time ive come across it. Well done.

[cptspaulding]

Very interesting, thanks Carolyn. I'm in a similar position, considering my options. Alas I don't have the skills nor the facilities to do the work myself so I'll be paying all the labour costs myself.
Thus I dunno which option is likely to be the cheaper...

[Tomo70]

That's a very interesting way of dropping the engine and gearbox with the crossmember and the hubs. I know when I swapped my engine over removed all drive shafts undid all the linkages on suspension and had real problems with lower link arm after reassembly.

I too went for option of engine of low mileage rather than faf with rebuild. Mechanic told me these engines are built by robots, you will struggle to replicate there work in a garage to the same standard, unless you have plenty of time.

[Carolyn]

Very interesting, thanks Carolyn. I'm in a similar position, considering my options. Alas I don't have the skills nor the facilities to do the work myself so I'll be paying all the labour costs myself.
Thus I dunno which option is likely to be the cheaper...

The challenge is (probably) finding a good face-lift engine, with a known history, for the right money.  If you add up the extra labour and parts for a re-build, I think a swap will cost quite a bit less.

[Carolyn]

That's a very interesting way of dropping the engine and gearbox with the crossmember and the hubs. I know when I swapped my engine over removed all drive shafts undid all the linkages on suspension and had real problems with lower link arm after reassembly.

I too went for option of engine of low mileage rather than faf with rebuild. Mechanic told me these engines are built by robots, you will struggle to replicate there work in a garage to the same standard, unless you have plenty of time.

Just about all high-performance racing engines are hand built.  As you say, it does take time, the kind of time and care a commercial garage can't invest.

[shnazzle]

Personally, from what I've seen on here, I'd be tempted for a rebuild.

Reasons I've amassed so far (including some personal choices) :

1) There seem to have been changes to the piston design up to late 2006. What are the odds of finding a good 2006 engine?
2) Knowing exactly what the state of the engine is, vs game of luck
3) vvt-i valve seems to get stuck, and is hard to notice when it does. With everything being rebuilt you'll inspect every little component and make sure it all works
4) pref: Adding of stage 1 crower cams
5) Honing cylinders, sorting out valve seats, valves, balancing pistons
6) Porting of throttle body
7) Smooth out intake and exhaust manifold and mating surfaces

With a replacement engine, I'd be less likely to do some of that work, even on parts that aren't part of the block. Because if you do, you might as well have rebuilt it.

I've taken a lot of inspiration from Nic's rebuild, jaworjawor's work on his 2zz and a work done by a few other members on here. Going that extra mile to make sure the engine is as sweet as it can be.

... And It's a project  s:) s:)   But I realise if this has been your job for years, it's not so much a project. But it is fun

[Carolyn]

Personally, from what I've seen on here, I'd be tempted for a rebuild.

Reasons I've amassed so far (including some personal choices) :

1) There seem to have been changes to the piston design up to late 2006. What are the odds of finding a good 2006 engine?
2) Knowing exactly what the state of the engine is, vs game of luck
3) vvt-i valve seems to get stuck, and is hard to notice when it does. With everything being rebuilt you'll inspect every little component and make sure it all works
4) pref: Adding of stage 1 crower cams
5) Honing cylinders, sorting out valve seats, valves, balancing pistons
6) Porting of throttle body
7) Smooth out intake and exhaust manifold and mating surfaces

With a replacement engine, I'd be less likely to do some of that work, even on parts that aren't part of the block. Because if you do, you might as well have rebuilt it.

I've taken a lot of inspiration from Nic's rebuild, jaworjawor's work on his 2zz and a work done by a few other members on here. Going that extra mile to make sure the engine is as sweet as it can be.

... And It's a project  s:) s:)   But I realise if this has been your job for years, it's not so much a project. But it is fun

You make some good points - especially points 2 & 3.  Obviously, if you're changing pistons and rings, you'll hone the cylinders.  Most seem to agree that well looked after post 2003 engines have much less of a problem with oil control rings,  A dodgy VVT-I valve can be dealt with without a rebuild.  Rebuilding is the kind of thing you'd want to do yourself, as opposed to entrusting the job to a garage mechanic.  I think many of our members would be totally unable to take on such a job, making a swap a more practical approach.  A low-mileage,crash damaged donor car that was looked after, is probably what to look for.

[lamcote]

I agree with shnazzle on this, that would be my choice too, but of course it's "horses for courses" so it won't be right for everyone.

I know the pistons were regularly redesigned but carolyn refers to the engine block redesign, does anybody know when this was applied?

[Carolyn]

I agree with shnazzle on this, that would be my choice too, but of course it's "horses for courses" so it won't be right for everyone.

I know the pistons were regularly redesigned but carolyn refers to the engine block redesign, does anybody know when this was applied?

According to my colleagues, 2002/3 with the face-lift engine.  All seem to agree that this re-design cured most of the problems, and regular oil changes made the engine reliable from then on.

[1979scotte]

From previous discussions we have had on the subject there where revisions to the pistons/rings later than 03.
From what I've been able to gather it wasn't properly resolved until the 06 model year.
Of course always happy to be proved wrong.

[Carolyn]

From previous discussions we have had on the subject there where revisions to the pistons/rings later than 03.
From what I've been able to gather it wasn't properly resolved until the 06 model year.
Of course always happy to be proved wrong.

No it wasn't, but... out of curiosity I took a look at the 'oval bore/precat failure register on this forum.  All but one were pre-facelift.  The one post facelift engine turned out to have a bad history.  Most on here have done very well with 2003 - 2005 engines, so the odds are on your side, swapping for anything 2003 on...with low mileage and good history.

[1979scotte]

That register isn't that current to my knowledge.
Engine was changed later than 03 as well 99% certain of that.
Mattperformance had seen failures in later cars.
I agree regular oil changes keep the gremlins at bay.

[1979scotte]

 m http://www.honestjohn.co.uk/forum/post/ ... m?t=101823 m

[Carolyn]

That register isn't that current to my knowledge.
Engine was changed later than 03 as well 99% certain of that.
Mattperformance had seen failures in later cars.
I agree regular oil changes keep the gremlins at bay.

I agree that later engines can fail.  But,then, all engines can fail, especially if they're not well maintained.  Looking at the odds on here. and given that nobody's going to part with a 2006 engine.....

[shnazzle]

That register isn't that current to my knowledge.
Engine was changed later than 03 as well 99% certain of that.
Mattperformance had seen failures in later cars.
I agree regular oil changes keep the gremlins at bay.

I agree that later engines can fail.  But,then, all engines can fail, especially if they're not well maintained.  Looking at the odds on here. and given that nobody's going to part with a 2006 engine.....

Exactly!
For this reason alone my preference goes to rebuild with newest of the new pistons, rings, seals, shells, etc etc. From all the reading, the block hasn't changed since at least 2003. Not even sure the pre-fl block is any different.
But you;re also right in that this isn't for everybody. I hope to do it, but only with guidance from experienced people. I fully expect it to cost up to 2k with all the things I want, but then I am 100% certain that it's as good as it can be. A 450 quid engine dropped in is all well and good but...what are the odds of finding a block from a person you trust to be telling the truth about their maintenance regime?

[Carolyn]

fair enough.  What would you advise Cptspaulding (above)?

[lamcote]

I have also heard MattPerformance talk about revised oil galleries in the block so I would be very surprised if the block wasn't altered at some point. I am hoping it was 2003!

[Jrichards20]

I know you haven't asked, but this is my advise. Take the rocket ship engine out, drop it in the mr2. Then you have a practical rocket ship that give you the best of both worlds. Plus you'll have largest powered mr2 in the world. Good Luck!  s:) s:)

[Carolyn]

I have also heard MattPerformance talk about revised oil galleries in the block so I would be very surprised if the block wasn't altered at some point. I am hoping it was 2003!

Perhaps it would be helpful to get members who do have post facelift engines to share how they're doing on oil consumption?  How's yours?  How many miles?  

Or just a topic put up by the forum on 'Oil Consumption' asking for details, year and mileage?

[Carolyn]

I know you haven't asked, but this is my advise. Take the rocket ship engine out, drop it in the mr2. Then you have a practical rocket ship that give you the best of both worlds. Plus you'll have largest powered mr2 in the world. Good Luck!  s:) s:)

Hmmm... the 10 second run time could be an issue!

[shnazzle]

fair enough.  What would you advise Cptspaulding (above)?

My humble opinion matters not haha. I think the likes of Wabbitkilla, loadsawine, Spit, jaworjawor, etc etc can provide the best answers as they've all been there and done it.

For Stuart (cptspaulding) the replacement engine is definitely cheaper. Plug and play essentially isn't it? Albeit a lot of plugs and pray for play.

As I said, I would fully expect to spend at least 2k on the steps I want and doing it myself with some help with the more precise things.

[Alex Knight]

I know I've banged this drum before, but if I was going to the effort of swapping a 1ZZ for another four cylinder, I would use a 2ZZ.

Advantages:

Reliability - despite many hundreds of *hard* track miles, it's been faultless. I do not need to check oil levels before, during or after a trackday, as it simply doesn't consume any.
Power - Obviously.
Torque - The 2ZZ has a larger area under the curve than the 1ZZ *everywhere*. This is amplified by the closer and shorter gearbox ratios.
Ease - It's such a simple swap, it can be done in a day if you know what you are doing.

Disadvantages:

Cost - If you are canny, you can do the swap for little to, or even no money. Conversely, it can be quite expensive if you're not clued on.


Overall, it's a cost effective, reliable, powerful, easy conversion. I wouldn't hesitate to jump in my car and drive half way around the world.