Precat Inspection - a worthwhile excersize!

[GSB]

Just inspected my precats, (killing time at work) and have found signs of slight degradation since my last inspection, which was roughly 2000 miles ago.

Last time I checked, they were perfect, now it looks as if the matrix on both precats has started to degrade, with tiny parts of the 'webbing' on the tops of a few of the individual cells starting to recede. Its nothing like as bad as some that I've seen, in fact its barely noticable at all, I had to get a better torch to be able to see it clearly, so I've caught it very-very early on.

Just for info, the oil is perfect, the engine is as strong as ever, and it shows no signs of any other problems at all... The car is a 2001 model, with 32,000 miles.

The degradation thus far is that minor that I'm fairly confdent a Toyota tech will tell me its normal... So next week the manifold is coming off for a de-catting session. I'll take a few reference photos for you all.

[Anonymous]

any pics would be great. i want to check mine but havent got round to it yet.

do i need an 02 socket to be able to check the pre-cats??

[Slacey]

Nice one Grant. I'm still waiting for the 'how to' from the States, so this could prove very useful.

[Slacey]

do i need an 02 socket to be able to check the pre-cats??

Yes, as the wire prevents the use of  standard 22mm socket.

[Tem]

do i need an 02 socket to be able to check the pre-cats??

Yes, as the wire prevents the use of  standard 22mm socket.

I vote for no  s8) s8)

If you open the manifold cover bolts, you can twist it just enough to open the other sensor from under the cover with a normal "open" 22mm wrench. Then you can slide the cover off and get free access to the other sensor.

O2 socket just makes things easier  s8) s8)

[Anonymous]

its ok ive ordered myself a 02 socket now. for £8.66 i thought i may aswell get one.

[Anonymous]

its ok ive ordered myself a 02 socket now. for £8.66 i thought i may aswell get one.

[topic drift]
Crankshaft should be on commission  s:lol: :lol: s:lol:  
[end of topic drift]

  s:oops: :oops: s:oops:

[GSB]

Well, they're out... and just in a nick of time too. The 200 or so miles I did over the weekend had caused further very noticible deterioration. Frankly, I'm shocked at just how quickly these things go bad. I should think that my engine will now give a very good indication over the coming months as to weather the problem of grenading 1ZZ's begins or ends with the cats breaking down.. Watch this space...

As for the job itself, its actually pretty simple, provided nothing goes wrong... I've just spent 2.5 hours drilling a sheared fu*@ing stud out of my manifold.  s:evil: :evil: s:evil:   Actually removing the pre-cats is a doddle, simply a case of getting happy with a hammer and screwdriver until they fall out, and then I rinsed everyything out with high pressure demineralised water. Not a commodity everyone has I know, but tap water will do just as well. I'm wary of using any kind of cleaning chemical as I dont know what effect it'll have on the O2 sensors.

The ceramic cat material isnt something I'd like to have floating around in my bores, in a wear contest of steel versus this stuff, the ceramics going to win every time, it might not be very strong, but mechanically speaking the particles are as hard as nails. God knows what Toyota were thinking when they put them in there...

I've taken a load of pictures, which I'll upload somewhere and then post a little write up with them tomorrow.

[Anonymous]

looking forward to the write ......

[GSB]

looking forward to the write ......

 m http://www.mr2roc.org/forum/viewtopic.php?p=44840#44840 m

[GSB]

Well, the cars done about 2000 miles since the de-cat, and all is fine. no increased oil consumption (doesn't use a drop between services) and no odd noises, or dodgy performance...

[Anonymous]

im going to check mine again tommorrow as ive nearly 100 miles since i last checked them and one of them looked a bit dodgy  s:? :? s:?  ...