Turned 100,000 miles today & still with pre-cats!

[ChrisGB]

I have 109k and never used any oil

Not up to that sort of mileage yet, but have always run on the best available oil and have never had a car that drank oil, even out past 170,000 miles.

Chris

[Anonymous]

I have a face lift 2004 mr2 covered 40k no issues to date, having taken advice of both Silverstone Racing and Toyota Mech, the de cat proceedure is a total waste of time and money on a facelift model

They both however stated would recommend on a pre 2003, even if the Toyota chap was somewhat hesitant in actually recemmending as such

A straight answer at last, facelift cars leave the pre cat well alone unless you want to waste money for the sake of it?

Really? Please explain then why we have at least one member with precat/oval bore failure on a facelift model?

The correct statement is that facelift models are far less likely to suffer it, not that they are immune.

[Anonymous]

I don't believe there is a precat problem, I believe its an oil control ring problem, after all that is the problem Toyota fixed, they haven't ever changed the design of the precats. If you get a pre 2003 engine to 100K you're doing well.

I agree with you 100% on that Rob, why else would Toyota change the piston design in 2003.

Precats as a individual component do very little except to reduce your emission during cold start - good old yanks hey, so when they fail, it's either as a result of someone hitting them or taking a heavy knock or another component failing which in turn causes the precats to fall to pieces. Those people who decide to run and ignore this, run the risk of either total oil loss or bearing failure due to precat dust - you take your chance I say and good luck with your decision and if you do achieve over 100K good for you.

Another problem that people are facing is the previous owner history, cars are becoming more affordable but if the car as not been treated right - buyer beware.

Rob.

With over 30 years workshop experience I like to think I know a little bit about the internal combustion engine and have to hold my hands up in agreeing with the above from day one of joining this wonderful forum many years ago.

I like to give advice when I can and have on many occasions acted on advice that has reaped benefits, unfortunately  things have gone the other way  sometimes, where it hasn't worked out according to plan - but at the end of the day that is all it is........advice.

It will always be up to the individual which direction to take, the bias towards damning you to hell for keeping pre-cats in has always been prevalent here and the horror expressed by new members when reading about their ticking time bomb cars is an unfortunate prequel to their introduction.

Thank you to the OP for being proud of this achievement and giving some of us members confidence in our own beliefs without needing to berate positive reports.

[blobb]

I got 160,000 out of my pre-facelift. It drank oil at an alarming rate but I kept it topped up. No matter what the reason I was more than happy with the miles per £ spent. Head gasket went in the end. I never bothered checking the pre-cats and never failed an MOT on emissions (odd windscreen wiper though) so presume the main cat held out to the end. It never missed a beat till the day it died and I worked it pretty hard. Fantastic car, even with all these terrible design flaws that are supposed to be dealt with urgently or woe betide. Just my experience of "pre-cat failure". Note to OP though, check your radiator, it's probably in pieces by now.

[mrzwei]

I hated driving my MGF because I was so worried about K series head gasket failure; Unfortunately, I crashed it and wrote it off before it happened   s:lol: :lol: s:lol:

[uktotty]

With over 30 years workshop experience I like to think I know a little bit about the steam engine

Fixed that for ya  s;) s;)

[Two's Company]

I have a face lift 2004 mr2 covered 40k no issues to date, having taken advice of both Silverstone Racing and Toyota Mech, the de cat proceedure is a total waste of time and money on a facelift model

They both however stated would recommend on a pre 2003, even if the Toyota chap was somewhat hesitant in actually recemmending as such

A straight answer at last, facelift cars leave the pre cat well alone unless you want to waste money for the sake of it?

They are wrong - there do seem to be less pre cat failures on post 2003 cars following the changes to the engine but I have seen the pre cats breaking up on a 2003 car that had just had a new manifold.  Dan's car I believe.

[Silverman]

I admire your style, but with a pre facelift car you might be heading for the big engine crunch.  I hope not, but as you, say, 100k sports car engine miles ain't bad.

This topic always brings about (understandably) loads of interest and yet the Club will not raise the matter with Toyota ?    s:? :? s:?

[uktotty]

The problem does not exist with Toyota!
They will give you a free engine for something which is not their fault but there is and never has been a precat issue.
Recalls are very expensive you know

[mrzwei]

Good point that because the issue which  they replace the half engine for is the failed oil ring / oval bore thing which is for up to 7 year old cars with a full Toyota service history consuming more than a litre of oil in less than 1000 miles. Precat's what the fuck are precat's  s:D s:D

[Mike68]

Decided against replacing pre-cats 2 years ago on recommendation of Toyota specialist as car had done 80,000miles already and all the bolts looked as if they would disintegrate if I tried!
 
Using oil on an increasing basis but probably less than an Mazda RX-8 and I just check regularly and top-up every other weekend but cheaper than replacing engine!

I think it's strange that you are suprised of the response of fellow forum members to be honest. The toyota specialist has given you wrong advice and I'm not sure of the reasons for his/her advice. If it's purely down to getting the studs out then they will have to come out when you replace the engine, the oil burning will continue after the pre cats are removed so the replacement engine will be on top of the oil. As for the comparison with a mazda, they may not have pre cats so the issue is not critical as with the MR2 roadster.

Above all, your statement may sway others who are considering taking out pre cats to keep theirs in only to have engine failure in the future. There is enough evidence on here to show this is a problem and so far you have been lucky but you must realise that the engine could go at any time with no warning, it only takes one small fragment and game over for your engine. Sandmanmr2 has an 06 mr2 which had signs of pre cat breakdown at very low miles.

If you're concerned about the manifold studs why not try the Diddy method (may not be the choice of methods but it worked for him) by removing the O2 sensors and the cat and knock the pre cats out in situ.

Go and bury your head in the sand if you want but dont have a go at forum members who are only trying to save you heartache and further expense.

[frogger]

Whilst I completely agree with the rest of the above post, I don't think the OP was in any way having a go at any forum members - the only comment that could possibly be taken that way was the lighthearted sentence "Thanks for the doom and gloom to add to my day!".

The rest of this thread has just been other existing members in agreement with each other mixed in with just a little bit of the usual political biccering midway   s:lol: :lol: s:lol:

[Gif]

A straight answer at last, facelift cars leave the pre cat well alone unless you want to waste money for the sake of it?

It cost me about £30 for the gaskets, £5 for some exhaust bolts and about a day of graft.  I think that's damn good insurance against pre-cat failure even if there is only a one in a million chance of it happening   s:D s:D    "Waste money for the sake of it", oh no, it's call risk management!

[mrzwei]

No wonder marketing and advertising work so well, we all just bite so easily   s:lol: :lol: s:lol:  .

[ChrisGB]

I think that with a standard facelift car, I would (did) not bother taking out the precats but did replace the lot with a PPE setup. The evidence points to precat failure usually being down to excessive oil use. As for Toyota not recognising it as a precat problem, that is because they have the same issue of excessive oil use on other cars using the same engine, where precats are not fitted.

However, oval bores caused by blocked oil control ring returns are not the only possible cause of precat degradation. A misfire will quickly overheat the precats, as will anything else that leads to too much combustible material in the exhaust side (overfilling, very poor quality oil shearing down and burning off, dribbly injector, marginal o2 sensor or MAF etc.) Then there is engine wear, has the engine been abused from cold, fed on cheapo oil, had a poor quality filter fitted, missed a drain interval, suffered from fuel dilution issues due to only being used for short runs?

If you are mapping, running too rich could cause problems as well. Potentially, because they are ceramic and relatively brittle, alterations in vibration modes could cause problems too. If you run too much advance, this could cause knock and change the vibration modes (I have seen this kill several gearboxes before it was figured out) or an aftermarket exhaust could potentially change the way the manifold resonates (though it is unlikely because of the flex couplings, a change in return pulse form could cause issues).

At the end of the day, for a pre facelift car, it is a no brainer. To go hand in hand with this, I would also advise using a high detergency fully synthetic oil from new to help keep those oil control ring lands clear. For a post facelift car, the probability of a failure are much lower if it is running properly. It is down to the individual to decide, maybe when the miles or oil use start to climb would be a good time? Or just whip 'em out for peace of mind anyway.

Chris

[mrzwei]

Just reading the June 'Car Mechanics' mag (the one with the roadster service shedule in it, thanks Roger) and page 81 lists an 'Engine Restorer and Lubricant ' product basically designed for high miles engines. Obviously take it with a pinch of salt but basically I think these sorts of additives are thick goo temerature resistant substances which will help reduce oil consumption, particularly in conjunction with a thicker oil. I used STP, a similar sort of product, many years ago to good effect.
Again, only if it's the daily commute and you don't want to rev the nuts off of it   s:D s:D  
 m http://www.AmericanTechnology.co.uk m