Precat removal - How I did it...

[Steve Green]

I can imagine the average mechanic, with no real knowledge behind the need to remove the precat, would happily use compressed air to blow out any loose debris, and blow it into the cylinders through whichever valves are open at the time. Not a good idea.

Fine when it is off the car.

[Anonymous]

I wonder how much cr*p he breathed in while doing this.
Im going to try knocking some out from the top without taking the manifold off, just to see how feasible it is.
Remove main cat and sensors, run in water to damp down, knock out material from above, wash thru with water. Refit cat. Ive been looking for an endoscope to make sure all is clean first. Just bought one off fleabay, soon as it gets here Ill have a go on a spare car.

[AmeR]

Easiest way is to be able to hit it from the bottom AND use the O2 sensor holes! With the amount of dust and bits etc that comes out, I thoroughly recommend always removing the manifold and doing it away from the car, followed by a good clean prior to refitting!!

Or Che, Zero, etc as an alternative is slightly easier!

[Wabbitkilla]

Not removing the manifold sounds a bit of a nightmare happening, you will have exhaust valves open and it's obvious that material could find it's way into the cylinders imho.   s:? :? s:?

[Anonymous]

Im hoping to attach a vacuum to the bottom of the manifold and run it full time while bashing out the stuff. Got to try it just for the experience.

[rodenal]

If you were going to do it I'd actually make up a pipe of some sory and put the vacum into the o2 sensor hole - you won't remove much of the material from the top, needs a good bit of persuasion from the bottom.

[Anonymous]

I see your point. I just want to avoid breathing, or having that stuff on my skin or eyes. Just have to get a CSI suit n gogs/mask.
Tape hoover to O2 hole and have a go.

[Esinem]

Is there any chance that precat removal will bring the engine management light on? I hear this will be an MoT fail next year. The thread on garages that will do it doesn't have anyone in South/Central London. Any recommendations?

[stargazer30]

Is there any chance that precat removal will bring the engine management light on? I hear this will be an MoT fail next year. The thread on garages that will do it doesn't have anyone in South/Central London. Any recommendations?

EML light is an MOT fail but no pre-cat won't cause an MOT fail.
Removing the precat doesn't bring on the EML, unless you drop an O2 sensor in the process or the like  s:D s:D

[Esinem]

Thanks, Stargazer30. Good news.

[Chris H]

hi everyone,

                this is how you do the pre-cat removal........drive over to warrington
and have D!ck2ki remove them for you,just like i did and also picked me up a
set of mud-flaps.
               TOPMAN,thanks again d!ck,enjoyed driving the 2 back today.......  s:bounce: :bounce: s:bounce:

[Anonymous]

Sorry it took so long! I thought we were going strong at 90 mins till I found the stripped manifold/cat stud. Lesson to self, always check condition of studs before trying to refit manifold!
5 hours later, drilled out stud, fitted brand new one, Bobs your wassit!

[Chris H]

Not to worry D!ck,had the experience of driving your monster van home and
back to you today.........  s:) s:)

[Anonymous]

I bought my 2 on the 2nd Dec.

Read all about precats on this forum.

Put car up on ramps this morning at 10am.

Pre cat material now sitting in an old washing up bowl!    s:D s:D   SIMPLES!!

Honestly, found removing the bolts that attach the manifold to the cat section was the hardest bit.... very tight, needed a long wrench on em!

Apart from that it is a very straight forward procedure and I wouldn't pay a garage to do it if you are the slightest bit handy with the spanners and are not of a nervous disposition.

It is going back together tomorrow as I'm off to work now.... unless that is I replace the gaskets on it...

[onion86]

I did mine on my 1st 2 at a bit over 30k miles, the 3 amigos (as you've stated) were very difficult to get off, the gaskets were still in a pretty good condition though and I reused them. When I fitted my turbo 15k later I did buy a head manifold-block gasket as the condition was a little worse by then. I'd say it depends on the condition of the current ones, think it was around £18 for that one alone.

[onion86]

Managed to remember to get my o2 sensors off today to check out the precats on the new car, still in perfect condition after 66k miles! Think I'll leave them in until I install the turbo as I don't use the car much and that will only be about 3 months so not worth the faff.



I also had a little fish around in the rear nappy to clean it out and found the Flywheel Housing Cover   s:shock: :shock: s:shock:   Is it likely to get full of gunk/cause issues if I don't put it back on just yet?

[Anonymous]

Anyone have tips on removing the 14mm bolt hidden behind the manifold? What tools/extensions did you use?

[g5elb]

Just removed my pre cats yesterday,what a releif.Kept reading all these threads and i was getting to the stage where i didn`t enjoy driving it anymore just in case it ******* the engine up.
The job was easier than i thought it would be,started at 10.am and was done around 2.30 ish all back together no warning lights and no grazed knuckles (bonus) anyone nervous about doing the job shouldn`t be as you get the satisfaction of knowing there out and that the job is done correctly.

[AckersMR2]

Wonderful post from yours! I like your post very much.You tell about designing the MR2 Toyota went down the path of making it a Ultra Low Emissions Vehicle (ULEV). I think also you should brief  about addition facts, I mean designing the MR2 Toyota  facts.

Is it just me or has the ROC suddenly been targeted with spam posts from foreigners offering Moody Gold and learning courses   s:lol: :lol: s:lol:     s:x :x s:x    s:x :x s:x    s:x :x s:x

[Thorpeymr2]

hi guys,new to the forum and mr2 ownership i have a march 2002 model and i guess i need to remove the pre-cats? would it be ok to replace the manifold with a stainless steel one,i guess this wouldnt have the pre-cats in? thanks pete

[spit]

would it be ok to replace the manifold with a stainless steel one,i guess this wouldnt have the pre-cats in?

Yes. Many go for this option rather than breaking up the precats and cleaning out the original manifold.

[Thorpeymr2]

thanks thats good to know  s:) s:)

[Anonymous]

Hi I'm a new member on here. My girlfriend owns an 04' mr2, great car. I owned a mk2 and thought they would never improve on that. Anyways I removed the pre-cats today, relatively easy if your handy with your tool. The only thing I will mention be careful with the 3, 14mm nuts on the lower part of the pre-cat chamber. Use a hex socket if you can to prevent rounding the nut and as much wd-40 as you can. We shall wait and see what happens with the car from now on. The car was at 60,000miles and the cats were perfectly intact.

[Lurch]

For those of you that dont know, when designing the MR2 Toyota went down the path of making it a Ultra Low Emissions Vehicle (ULEV). Doing this meant adding a whole load of extra emmisons control equipment to the engine, chief among these being 2 additional catalytic convertors installed in the exhaust manifold. The theory behind it being that when starting from cold, these cats heat up and get working a lot faster therby reducing the emmisions that bit sooner.

The problem with these cats, is that in order to endure the very high temperatures in the manifold, they have to made of a ceramic material. This ceramic might be good with high temperatures, but is incredibly brittle and doesnt like vibration. The particles that do break free are also very-very hard, so if they manage to get into the cylinders they aren't going to be to friendly to the insides of yor engine...

I've been regularly inspecting my own precats for a while now, and they've always been in good condition, However after a recent check revealed that they were starting to deteriorate, I decided it was time they came out beofe they took my engine with them. The first signs of deterioration were noted at around 30,000 miles, 2000 miles after my previous inspection. 200 miles later, the situation had deteriorated even further. These cats go bad very-very quickly...

Heres how I removed the cats...

Note: Clearly, neither I nor MR2-ROC can condone you ripping lumps of emmisions control equipment out of your car. Its safe to say the the warranty on my manifold at least and probably my main cat as well have now been well and truly voided, so the same will go for you.  Basically, if you decide to go down this route as I have, you're on your own... On the plus side, if its not in there, it cant break.  s:wink: :wink: s:wink:

Toolkit required

Trolley Jack
Axle Stands
10mm spanner
10mm socket on 6" extesnion
12mm spanner
12mm socket and various extensions
14mm socket
Hammer
Vice
Long flat bladed screwdriver
High pressure water or air supply
Large vocabulary of swear words

In order to remove the precats, you first have to remove the exhaust manifold from the car, Care should be taken to apply penetrating oil to the various nuts and bolts some time before undoing them

1/ Jack up the rear of the car and place on axle stands.
2/ Remove the splash guard from under the rear bumper
3/ Remove 3 bolts from the forward splash guard to let it hang down.
4/ Remove the 3 14mm nuts that secure the main cat pipe to the manifold

In the engine bay;

5/ Using a 22mm O2 sensor socket, remove the 2 O2 sensors from the manifold.
6/ Remove the 4 bolts securing the manifold upper heat shield
7/ Remove the 2 bolts that secure the lower part of the manifold to the engine block. These are 'behind' the manifold and not readily visible. ! of them is 12mm, the other 14mm.
8/ Remove the 5 nuts securing the manifold to the cylinder head.

The manifold can now be lifted out of the top of the engine bay.

Decatting the precats...

Actually getting the precats out is pretty simple, here's what mine looked like from above and below before I started, you can see some of the degradation thats taken place in the first photo:



And here are the surgeons tools:  s:wink: :wink: s:wink:  


Removal is simply a case of attacking the precat matrix with hammer and screwdriver until its broken up into lumps small enough to be able to get them out through the lower exhaust port. The ceramic material gives up very easily, it only takes 1 or 2 taps on the screwdriver to do this...  s:shock: :shock: s:shock:  


After digging around for a while you will also expose the glass fibre that surrounds and supports the cat matrix, this has to come out too.



Once out you'll have a big pile of very useless, but rather expensive catalytic material left over. I beleive some places do recycle this stuff to reclaim the precious metal content, so if your now feeling guilty about your effect on the environment, this could be a way to ease your concience  s:wink: :wink: s:wink:  


Once its all out, you'll be left with an empty manifiold like this;


You now need to clean it, as there is still an awful lot of potentially damaging dust and particles left inside. I would recommend high pressure water like a jet wash or an airline for this, as an chemical residue from solvent cleaners may have a damaging effect on the O2 sensors.

Once clean and dry, re-building is simple the reverse of the process used to take the manifold out in the first place.


Happily, I've not noticed any increase in noise level from removing these. Performance certainly isnt any worse, and in fact the car may have benefitted in the form of slightly increased torque, but I cant say for sure... What is certain though, is that the pre-cats are going to have a hard time damaging my engine from the workshop bin, and I'm a lot happier now that these ticking time bombs are not a problem...MOT tests wont be a problem, as I still have the main cat in place, which is more than capable of doing the work. I dont have a ULEV car anymore, but I do have one that with a bit of luck will last a bit longer.

Can any body please send me a link or pm with these photo's attached as they no longer seem to be avaialble , i appreciate it was a few years back but i am looking at removing my precats and would like to try and find some good pic's on how to do please if any one can help.
My 2003 has now only done 7k from new but looking at all the posts would like to get them out and still use the original manifold.
Thanks

[StuC]

Here is a very similar thing over on Spyderweb with pictures