Precat removal - How I did it...

kanujunkie · March 26, 2006, 09:59

yep what Mark says, the pre cats only control emissions in the first 5 mins or so from cold, once the main cat warms up it takes control of the emmisions. I firmly beleive that Mr.T's people can sometimes be as thick as 2 short planks, saying things without thinking s:roll: :roll: s:roll:

Anonymous · March 26, 2006, 12:49

Ok thanks very much, thats put my mind at ease.
I wanted to thank GSB for the info on how to remove the pre - cats its excelent. I would advise anyone who wishes to carry out this work to use the instructions on this forum. s:wink: :wink: s:wink:
p.s. I f anyone in the Kent area is looking to remove pre- cats I am only too happy to help/advise, pm me. s:)

s:)
Andi

Anonymous · March 26, 2006, 13:21

No one in my neck of the woods then.

Several garages have refused to do this work.......

My 2 local Mr T's wont do it either.........

I wouldnt be able to do this myself, but am really worried about this. I dont think mine are damaged, as the car drives wonderfully, and doesnt use any oil at all, but I still want them out. I have a warranty on the car anyway, although not a Mr T one, and I have checked that this does actually cover engine failure - as long as its not through my own fault, in not caring for the car i.e driving with no oil in it :-) :-) :-)

Anonymous · March 28, 2006, 21:54

Evening all - went back to Mr. T today and actually spoke to a guy at parts who was really helpful. Ive now ordered all the gaskets required for replacement after pre-cat removal as follows -
Gasket Manifold 1 off T17173-22010 £14.05
Gasket Exhaust 2 off T90917-06065 £2.76 each
Gasket Exhaust 1 off T17451-22060 £7.57
Don't forget to add VAT to this - it may be painful for a few gaskets but its much less painful than buying a new engine any day. s:shock: :shock: s:shock:

You will probably find that most Toyota dealers have to order these in which takes 48-72 hours.
Just thought this may help some of you who are planning this work.
Bear in mind my car is a 2000 import (not sure if there are any differences with later or GB spec models ?) s:wink: :wink: s:wink:

As an aside I have come up with a design for a twin exit st. steel system (cat back) which exits just to the right hand side of the rear number plate.
Obviously the rear grille infill would have to be modified/ replaced and I plan a metal replacement grille. s:idea: :idea: s:idea: The exit pipes will be 76mm diameter and positioned one above the other as per VX220 (but better). s:D

s:D Before I start playing with the welder does anyone know if there is a maximum height from the ground that an exhaust can be or envisage any probs?1?
Thanks
Andi s:lol: :lol: s:lol:

Anonymous · March 28, 2006, 22:09

my apologies for going off topic. sounds interesting. are you planning on making these to sell? also ( s:cry: :cry: s:cry: shows TOTAL ignorance s:cry: :cry: s:cry: ) what does cat back mean?

Anonymous · March 28, 2006, 22:23

Hi Nelix,
I will see how this turns out first, I have made a few systems in the past but only for my own vehicles. Watch this space!!
Cat back means from the catalytic converter backwards i.e. the last section of the exhaust if that makes sense. s:wink: :wink: s:wink:
Andi

Anonymous · March 28, 2006, 22:26

yes thanks, good luck, and first bags if you go into production! s:)

s:)

edward.carter · March 28, 2006, 22:50

Quote from: "saftmadred"whey hey s:D s:D i'm now pre cat free thanks to edward carters recommendation of an excellent garage in aldridge wasall and a very nice mechanic called bob
s:D s:D

all ok then, thats at least 2 he has done now, be doing them with his eyes closed soon s:)

s:)

Anonymous · April 16, 2006, 18:59

Gutted mine on Good Friday... everything came off smoothly. s8)

s8)
Pre-cats were perfect (thank god)

hour and a half to remove the manifold.
half hour destroying the pre-cats.
half hour putting manifold back.

Cheers to everyone who's posted advice and tips on doing this...i feel like a great car has just got better. s:D

s:D

Downside, while also changing the front pads and disks I found a screw stuck in one of my tyres. s:cry: :cry: s:cry:

markiii · April 16, 2006, 19:57

thik positive, good you found it, a high speed blow out would not be good

heathstimpson · April 16, 2006, 22:11

Quote from: "markiii"thik positive, good you found it, a high speed blow out would not be good

Too right as I experienced one of those many years ago and its a frightening experience to say the least s:? :? s:?

ash1809 · April 27, 2006, 15:50

Had my precat removed yesterday s:D

s:D

leon_in_uk · May 26, 2006, 11:45

while my new engine is in the garage. the bloke removed mine for me...

it was so easy to do when the manifold was already out my car.

just did it with a screw driver/drill and washed, air blasted out.. in no time at all.

quality...

Anonymous · May 27, 2006, 18:50

Removed the pre cats this morning, the only problem I had was heavy corrosion on the nuts and bolts, I soaked them in plus gas for about half an hour before starting, which did the trick. I took a gamble on re-using the gaskets and got away with it, no leaks. My only suggestion to anyone thinking of doing this job is to get your self 10mm, 12mm & 14mm 3/8 deep drive single hex sockets ( saves rounding of the nuts & bolts ). s:wink: :wink: s:wink:

kanujunkie · May 27, 2006, 19:53

just as a point for anyone that has them, DO NOT use bi-hex sockets, you will round them. As AJP says use hex sockets only

Anonymous · June 18, 2006, 20:50

Hi all im new to forum and have joined as iam going to buy a roadster in the next couple of weeks, here is my prob having read these post iam now very worried about buying one, mainly due to the fact that iam not in any way mec minded, i live in the south east (near Stansted Airport) does anyone know of a place that removes the precat in or around that area?

Anonymous · June 22, 2006, 10:39

Hi guys. New here, my joining being prompted after a conversation with a customer.

I work for a Toyota dealership(not tellin you which) in the service dept.
I was contacted by a customer who is presumably a member of mr2roc also, who asked about this apparent cat problem.
I thought Id a a bit to this thread, so Ive joined ya'll.
Ive been with Toyota for 4 1/2 years, and in that time Ive never seen or heard of a precat failure on the mr2 roadster model(fitted with 1.8vvti 1ZZ engine)

I checked all bulletins from TGB this morning and found non, I also checked product reports from dealers and found non.

There is a known problem with the 1ZZ engine with a piston and ring fault. Basically the oil drain holes in the piston are insufficient, causing them to clog, thus causing the oil control ring to also carbon up.
This leads to excessive oil consumption, and regardless of oil type(semi/full synthetic) this cannot be seen in the exhaust(thanks to the Cat!!)
This often leads to bore scuffing and wear as carbon builds up, and oil level falls(especially as owners usually have little idea of what to do with a dipstick!!) This has lead to some engines being rebuilt/replaced.
Theres now a modified short block assembly(and piston/ring set) to cure this.

I cant find any evidence of precat failure, and have never witnessed the same myself.
Guess that doesnt mean it doesnt exist tho.
Any further help I can be , let me know.
Anyway, thats my 20 cents worth

Rollazuki

Mr2's are prone to exhaust damage from rear end shunts. Ive seen several 'cosmetic' repairs done to them, and found the exhaust to have been damaged underneath, but ignored due to cost etc.

Anonymous · June 22, 2006, 11:41

Thanks for the interesting comments. I've held off doing anything with the precats on my April 2005 car because, although there is clearly a link between precat breakup and bore wear, I'm not sufficiently convinced of teh sequence of events. However, there do seem to be reports of cars which exhibited some degredation of the precats, have had them removed, and the engine has continued to run without problem.

Quote from: "rollazuki"There is a known problem with the 1ZZ engine with a piston and ring fault. Basically the oil drain holes in the piston are insufficient, causing them to clog, thus causing the oil control ring to also carbon up.

I'm guessing that this problem may be more pronounced with some types of oil (and some driving styles?).

QuoteThis leads to excessive oil consumption, and regardless of oil type(semi/full synthetic) this cannot be seen in the exhaust(thanks to the Cat!!)
This often leads to bore scuffing and wear as carbon builds up, and oil level falls(especially as owners usually have little idea of what to do with a dipstick!!) This has lead to some engines being rebuilt/replaced.
Theres now a modified short block assembly(and piston/ring set) to cure this.

Can you determine whether/when these modified parts were used in production? Can we tell whether our cars were built with the modified parts?

Anonymous · June 22, 2006, 13:06

Ill try to find out.....

As far as I can see, the oil makes little difference.
We use semi synth all the time, and have seen a.....'few'........zz engines go wrong. The pistons all show signs of the oil ring being carboned up, the oil return holes being blocked, and in most cases a lot of evidence of lacquering on the piston. The replacement pistons do have vastly different sized oil return holes.It seems to make no difference how its driven. Weve seen thrashed MR2's, pottered in Avensis etc. all with same symptoms. And non of them showed any smoke. Beware, smoke will not indicate an oil consumption fault. They all burned clear, even those doing 2 litres in 500 miles.........
Ill be honest as well, its such a good engine, that we've had em needing 3 litres of oil to top up(bear in mind the avensis holds 3.7l) and theyve run sweet as a nut after having the oil topped up. No rattles/knocks etc. Bloody good motor IMHO

OK, been checking. Seems the problem can apply to pretty much all the engines...... all the way thru to 3ZZ motors as in corolla and corolla verso, so appears that pretty much all MR2's can be affected.

The new piston is as follows. Instead of 4 oil drain holes, there are 8, with an oil drainage slit around the oil control ring groove.
This helps draining, and keeps the piston skirt cooler(apparently a problem with the early piston.
On some models(avensis etc) the sump has been enlarged to hold an extra litre of oil, inc a new dipstick. Not on the MR2, a lack of available space apparently. haha.

If this fault occurs, go see a dealer. Yes really. Even if outside the warranty age/miles, it'll be worth the trip..............................

s:wink: :wink: s:wink:

kire612002 · June 22, 2006, 14:54

[/quote]Can you determine whether/when these modified parts were used in production? Can we tell whether our cars were built with the modified parts?[/quote]

if you can tell us from which serial number started to use different pistons would be great.There are lot of rumors about that issue

thanks

Anonymous · June 22, 2006, 15:00

Dealer draws a blank there Im afraid
It would appear that the fault affects all zz motors(1 thru to 3)
as far as I can make out all MR2 models could be affected

kire612002 · June 22, 2006, 15:09

I was afraid of that.

thanks anyway

leon_in_uk · June 22, 2006, 16:03

what about my pre cat pic?

it has happened to 2 engines i have had... half the pre cat honeycomb was missing.

Anonymous · June 22, 2006, 16:23

I think what he is saying Leon is that the precat issue is a symptom rather than a cause?

Anonymous · June 22, 2006, 16:44

certainly looks like its missing dont it.
Toyota do recommend a cat check after the new block etc is fitted. Done electronically by means of a waveform scan of pre and post cat oxy sensors. The insinuation is that the excessive oil burning may damage the cat. Maybe thats the cause of your cat damage.
Did your car burn any oil Leon?
Was the engine light ever on?
did the engine light work?
was it tuned/filtered etc.