Precat removal - How I did it...

[SeanieB]

Anyone able to recommend a garage/mechanic in the Oxford/Reading area - who can do the decat job?

What sort of price are we talking about?

[Richm10]

I just rang toyota and asked if they'd do mine. They said they'd never heard of this and not sure what it is exactly. I spoke to the head technician and he was also unsure but estimated it would take 3 hours and cost £280ish.

Is this correct!?

[MR TWO]

I am planning to buy an MR2 in the next couple of weeks, an of course I am concerned about the precats etc...

I guess many of the cars have had the engines replaced with the later version which apparently doesn not suffer from this catastrophic problem (according to Spyderchat).  Anyone know if there is a quick way the check which engine is in the car via serial numbers?

Thanks,

JEZ

[Jandaw]

All Roadster engines had precats and the only way to tell if they have been removed is physically by removing the O2 sensors or if an aftermarket manifold is fitted which doesn't have precats.
Of course you could take it on trust from the seller!

Of more concern should be oil consumption, it's that which destroys the cats in the first place.

Edit
Sorry that's not what you asked.

You'll need a 2005 reg car to have a chance of having the latest pistons and it seems engine numbers alone won't neccessarily guarantee the latest ones.

Try the search bar, there's loads of related info.

[MR TWO]

You'll need a 2005 reg car to have a chance of having the latest pistons and it seems engine numbers alone won't neccessarily guarantee the latest ones.

Try the search bar, there's loads of related info.

OK thanks for that!

[Tony1977]

Reading about the damage that precats can do is very worrying, I will be getting mine removed by a local garage. How much would you say is a cheap price to get this done guys. I havent got a clue. Cheers for any help you can give.

[Jandaw]

Read a little more. Precats on there own don't do the damage. If they fail its because the engine is burning oil to an excess so the damage is already done.
Remove the precats certainly but more to the point, monitor your oil consumption.
With the precats out you may be able to live with high oil consumption and shouldn't have to worry about spontaneous engine failure.
You should monitor oil level religiously (every Sunday?)  s:wink: :wink: s:wink:   and if it's acceptable just relax and enjoy life!

[Aki42]

Precast removal. I have just removed cats, when stripped I had to push mr2 forewords about 2ft, replaced manifold &everything else, started engine up and there was a large tapping noise from the engine, has any body had this trouble be fore.  aki42

[Mightyquin]

Spent some time this afternoon de-catting a replacement stock manifold - seems like it'll take ages when you start but you just need to get a bit brutal - hammering in a long screwdriver from the bottom and top alternately seemed to do the trick for me.

My car doesn't use oil and the existing pre cats are fine, but I'll be more confident knowing they're out and there's no risk. One little tap and crumbs of the stuff will fall out so it's easy to see how they could damage the engine if they start to break down.

Bizarrely I'm missing a heat shield bolt on one side from the existing manifold, and the 'new' one is missing the other side!

It's going into the garage for an Mot and service shortly so I'll get them to swap the manifolds over then.

[beavisrules]

Done mine this week.
2 hour job made 5 hours by bolts shearing under the car - not the easiest of places to get a drill.
109k miles on it, original exhaust still.
super lazy - just reused all the nuts/bolts and gaskets. no leaks.
pre-cat perfect , sharp and white squares  - drilled out with a 20mm masonry bit and a large screw driver.
uses a fair amount of oil. has hardly any blow-by, but does look like it has 'some' oil leaks , as well as burning a bit when booted.

[Reeflodge]

I have just bought my first 2003 MR2 Facelift Roadster with 77k on the clock and did not know about this Precat Manifold problem and now I am very worried!

When I purchased it I drove it 100 miles back to my home and it drove lovely although there was a little rattle at the top of the revs which the seller said was the exhaust and needed welding but did not know where!

He did have a new cat fitted just before he sold it but not the manifold.

Do you think it might be the cat breaking up in the manifold?

Is it a DIY job capable for someone who has already dropped the front Bumper and fitted new fog light, replaced the stock radio and repaired the electric aerial?

  s:( s:(

[shnazzle]

Put it this way, gutting the pre-cats is no more difficult. The bolts are just bigger, tighter and more plentiful.

That's just it about (simple) car work. As long as you stay out of the engine block, there's little you can do wrong as long as you read up and tackle the job in a structured way.

Removing the pre-cats means taking the manifold off, so it means dismantling a fair few things from the engine bay and rear for access.

I'd say give it a go if you have the time and general affinity with a wrench and sockets.
I gave myself a day to remove pre-cats and install a TTE exhaust, I started at 9am and by 11.00 I was thoroughly twiddling my thumbs waiting for a delivery truck to come at around 13.00 with some bolts and a gasket.
By that time I had dismantled everything and removed the pre-cats. Never done it before. I set off installing a subwoofer and tinkering with a few other things.

Van came and within another 2hrs I had everything on, including subwoofer.

I had had a chat with my gobby neighbour, had lunch, watched TV and went out to get some wires as well.

So yeah..
Just do it haha

[CrazySX]

It's not that hard. One bit of advice. Get the nappies off and give the 3 amigos a soak in WD40 as well as the manifold nuts. Oh and the heatshield bolts. Well at least the ones you can see. If you do it a few times before tackling the job then everything should come apart a lot easier. The job itself is not that hard. It's just made hard when nuts and bolts don't want to budge.

[shnazzle]

WD40 is for the weak!
It's all about PlusGas.
PlusGas the crap out of every relevant bolt 2 days in advance. Takes 5 minutes, will save you hours.
I haven't used wd40 for anything other than removing stains off clothes and on door hinges since I got PlusGas

[Reeflodge]

Thanks I'm going to give it a go but I am going to be prepared!

Does anyone know what bolts sizes I will need as I may as well replace them as a go?
Also which gaskets do I need?

Thanks again

[shnazzle]

- donut gasket (exhaust to cat) £17
- spring bolts (exhaust to cat) £11 each
- 3 amigo bolts (pre-cat to manifold) £2 each
- 5 manifold nuts £2 each
- 5 manifold Studs £5 each
- 2 heatshield bolts £2 each

Gasket for manifold to engine as well. Although people have re-used them without issues.

That's the full list of bolts for the exhaust

[Reeflodge]

Thanks
where you getting those prices from?

[shnazzle]

They were the prices as quoted by Chris from the then-active CheapToyotaParts. They'll be slightly pricier from the dealer, but not by much.
I ended up replacing all of these bolts, but only because I had bought them and didn't want to waste them. I only really needed a couple new ones. The rest I sold onto people on here

[Reeflodge]

I have just removed my manifold and got to work with a hammer and screwdriver to remove the cat which looked like it would not have been long before it broke up!!!

Is it possible that if a very small piece broke off it could pass through the engine without doing any damage?

Before I put the decatted manifold back on would it be OK to stick the hoover nozzle in the manifold outlets just to make sure its free from any debre that might have fallen in when I was removing the manifold?

Also hoover out the 2 pipes that go down to the main cat?

[shnazzle]

I put the high pressure hose on it  s:) s:)  But yes, hoover is perfectly safe. I went for pressure wash to really make sure it was cleared out

[Reeflodge]

Sorry didn't make it very clear, I jet washed the inside of the manifold, I was talking about sticking the hoover nozzle in each of the 4 outlet holes on the block just in case something dropped in when I was removing the manifold!
Also hoover out the 2 pipes that go to main cat in case something dropped in there also.

[shnazzle]

Oh! No I wouldn't hoover the block to be honest. Nothing will be in there that can be hoovered. If you do do it, don't cover the entire port so that there's a locked vacuum in the port.

No harm vacuuming  the exhaust I'd say

[CrazySX]

WD40 is for the weak!
It's all about PlusGas.
PlusGas the crap out of every relevant bolt 2 days in advance. Takes 5 minutes, will save you hours.
I haven't used wd40 for anything other than removing stains off clothes and on door hinges since I got PlusGas

Is plus gas really that much better? What makes it so superior to WD?

[shnazzle]

WD was never meant as a penetrative fluid. PlusGas was made for that purpose; to unstuck stuck bolts.

I've also noticed that PlusGas doesn't make such a mess and it also doesn't have such a god awful smell that seems to stick around for days.

For me, WD40 is good to clean areas where metal touches metal and it lubricates a bit too.

Try it and see

[PhilzMR2]

I've just bought an MR2 roadster on an 04 plate (facelift) and I have a couple of questions regarding the precats:

If I want to check the precats, which O2 sensor do I remove? Or is it both? Left or right when facing the engine from the back of the car?

Also, presumably I could just replace the precats with one of the de-catted pipes that are available online, rather than hacking out the ceramic material from the old one?
If so, does anyone have a link to a de-catted pipe that they have used and definitely fits OK?

And finally, can anyone on here reassure me that they have removed the precats and then passed a UK MOT?

Many thanks for any comments!