Pre-cats: The Official MR2-ROC Information Thread

[Carolyn]

Until the very last few cars, the oil control problem in the basic piston design was never fixed.  So, in a way you're right, the Facelift engine is no better than the pre-facelift engine.  Yes they did 'upgrade' the rings, but the basic piston design flaw remained.

Trust me, I've had quite a few engines in bits.  If a car has always had regular oil changes, it can dodge the bullet.  Many do.

Sounds like you've got one that has always been properly looked after.  I came across one car that was one of the first sold in the UK.  Over 130,000 miles and one owner.  Engine was mint.  Mind you, the sub frame and gearbox weren't.

I don't think you'll find many of our members 'dissing' any of these cars. We're enthusiasts, not journalists, and we know a lot more about them than any journo.

[Ben]

I agree - my 'dissing' comment related to the buyers guides - Autocar, Pistonheads etc. - which tend to say 'buy the facelift - you won't have a problem'. We know it's not that simple but it would be good if the club was clear about when engines specs were changed - i.e. make it clear that it was well before the facelift.

I know I've got lucky (so far) with my car. It's got a full service history and both the sub frame and gearbox are good.

[shnazzle]

I have a long outstanding task to revisit the buyers guide I wrote on here. So that note is something worth adding.

However....

There is also evidence to suggest that the oil control ring changes as well as the newer piston design was introduced long before we think.
Just not in the UK...

So going off part numbers may not show all.

There's even evidence that cars who had warranty rebuilds by Toyota before 2006, already have the latest pistons, which reportedly only came out in 2006...in the UK....
Blame the US litigation culture for that one,or rather the UK's lack of it.

The main reasons for going to facelift (especially post-2004) are more around safety and bracing, as well as the styling (taste-dependent).

The pre-cat story is, as written earlier here, fraught with half-truths.

It's important we don't scare away people who want to, get, or can only afford pre-facelifts.

[spit]

Had a quick check today on the pair of mani-cat gaskets part number. It seems to have been misquoted earlier in this thread - post edited as follows:

CAT gasket £4.15 T90917-06066 X2, three amigo nuts T90179-10070 £1.85, burrows Toyota doncaster

[Mod]a quick heads-up - crush gasket part number is 90917-06065, not 06066 as stated.

06066 relates to a gasket used elsewhere in the Toyota range.

Can someone cross-check this for me and confirm? If I'm wrong I'll dive in and re-edit the edit!
Ta

[SteveJ]

Had a quick check today on the pair of mani-cat gaskets part number. It seems to have been misquoted earlier in this thread - post edited as follows:

CAT gasket £4.15 T90917-06066 X2, three amigo nuts T90179-10070 £1.85, burrows Toyota doncaster

[Mod]a quick heads-up - crush gasket part number is 90917-06065, not 06066 as stated.

06066 relates to a gasket used elsewhere in the Toyota range.

Can someone cross-check this for me and confirm? If I'm wrong I'll dive in and re-edit the edit!
Ta

toyodiy says you are correct -  m http://www.toyodiy.com/parts/p_E_200208 ... ?hl=17410B m

[Bossworld]

Can someone cross-check this for me and confirm? If I'm wrong I'll dive in and re-edit the edit!
Ta

Might as well remove my post remove it, I literally C&P'd from Facebook after a Google Search   s:? :? s:?

[DanThrax]

Quick one folks,

I've been to view a really nice mr2, well, much nicer than my current one at least.

It has had a lot of work done to it and is well look after but has a fairly decent mileage on the clock, trouble is the fella doesn't know if the precats have been removed or not.

Now, I'm no mechanic so I think trying to find out is above my level, but the car needs an o2 sensor replacing, would this be related to precat removal?

Cheers!

[Carolyn]

You'd have to take a spanner to a car that you don't own, to find out.  If the sensor that needs to be replaced is on the manifold (not the main cat), you will be able to see the top of the catalytic matrix when it's removed.

If the owner of the car doesn't want you to do this, it's not a big deal as you'll find out soon enough and (if the pre-cats are still there) getting them out is not a deal-breaker.

Odds are if it's had lots of work and been well looked after, the pre-cats will be gone.

You might even want to put a decent de-cat manifold on??  Even paying a mechanic to do it might well be worth it if your really like the car.

[DanThrax]

Not a bad idea actually getting a new de-cat.

Either way, the car is an import and touching 100,000 on the counter.  So I'd like to think that the pre cats are looooong gone!  But the owner won't have a problem with me taking a spanner to it, either myself or a mechanic.

[Chase27]

Thanks for this very useful post. I, too, have a pre-facelift. Mine is proper pre-facelift, being on a Y plate. It's with the garage having the precats ripped out and a new manifold bolted into place.

[Call the midlife!]

Thanks for this very useful post. I, too, have a pre-facelift. Mine is proper pre-facelift, being on a Y plate. It's with the garage having the precats ripped out and a new manifold bolted into place.

Just to clarify your post, if you're having a new, precat-less manifold fitted then I assume "having the precats ripped out" just means they're removing the standard manifold? They're not actually removing the precats from the standard manifold as well as replacing it??


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[Chase27]

You're right. That was imprecise language. I had the old manifold replaced with a stainless steel unit, new spark plugs, new air filter, oil change.

Feels great. Rorty engine sound and a definite positive tweak power-wise.

But best of all, I can relax about pre-cat disintegration...

[Call the midlife!]

You're right. That was imprecise language. I had the old manifold replaced with a stainless steel unit, new spark plugs, new air filter, oil change.

Feels great. Rorty engine sound and a definite positive tweak power-wise.

But best of all, I can relax about pre-cat disintegration...

Good stuff! Assumed that would be the case but just checking the garage weren't trying to have you over.
Enjoy!


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[Chase27]

Cheers

[Hamezi]

Hi,

To do with pre-cats.

I have removed mine and have also fitted a new exhaust manifold and a twin pipe exhaust system - both sourced from "Mr2"  Is there any liklihood of my compromising the MOT regs re emissions?

Many thanks.

[AdamR28]

Should be fine as long as you keep the standard cat and everything else in good order.

[1979scotte]

Hi,

To do with pre-cats.

I have removed mine and have also fitted a new exhaust manifold and a twin pipe exhaust system - both sourced from "Mr2"  Is there any liklihood of my compromising the MOT regs re emissions?

Many thanks.

None at all once the main cat is up to temp it takes care of everything.
Believe pre cats where to pass more stringent emissions laws elsewhere say california

[Ardent]

What ^^^^^^^ they said.

[Mr2m3]

Hi guys, I have a 2000 MR2 and recently found out about the precat issue. The car seems to have lowish power throughout the rev range, and not sure what the issue is yet. Oil level remaining stable.
If its a precat issue that is causing the problem would it now be too late for the engine?

Thanks.

[Joesson]

@Mr2m3

Firstly, hello and welcome to our club.
Are you a recent owner? Your reference to " lowish power throughout the range ", compared to what ? The M3 in your Member name, or a noticed deterioration over a period of time?

To check the condition of the precats, that are contained in the OE exhaust manifold soon after exiting the head.
If your car is OE the manifold is covered with a heat shield, protruding from the top of this are two sensors.
These sensors can be removed, typically first requiring a dose of penetrating fluid, and the use of a sensor socket,splitto allow for the sensor cable.
Once removed a strong light into the chamber will reveal either a Honeycomb filter material that is intact or otherwise.
If otherwise you have a pre cat problem.
Some cars in this condition will run for some time, others will not , dependent on previous and continuing use.
If the honeycomb is intact then the engine is in good health. These cars have been known to achieve 250K mileage on a well maintained original, if not well maintained they can die prematurely.
Much has been said on here and elsewhere about the causes for this but at 24 years and whatever mileage and past maintenance it is not too bad a result to be finding a loss of power.
Have a look and then tell us what you've got.

[Ardent]

Hi guys, I have a 2000 MR2 and recently found out about the precat issue. The car seems to have lowish power throughout the rev range, and not sure what the issue is yet. Oil level remaining stable.
If its a precat issue that is causing the problem would it now be too late for the engine?

Thanks.

Not burning oil is a good sign.
Just a heads up. The sensors are rather fickle and just looking at them the wrong way can be enough to upset them, so do not be surprised if you get an EML shortly after.
Omlette eggs etc etc