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The Idiot Guide to Precat Removal (Lotsa pics!)

89K views 226 replies 51 participants last post by  Stu UK 
#1 ·
From the first moment I got my Spyder, the first recommendation from everyone was "gut your cats!" But hey, that manifold is like right next to the motor! That's mechanical stuff! How am I supposed to deal with that? Well it turns out, that with the proper tools and a lot of time on your hands, its not that difficult.

Tools and consumables:

From my little precat removal experience, I've found out that the following is essential to an stress-free experience. I strongly suggest not starting this little project without:

1) deep and regular hex sockets (esp 12mm and 14mm)
2) breaker bar
3) PB Blaster
4) socket extension
5) lots of daylight

The essential tools that are required are:
1) ramps
2) 14mm, 12mm and 10mm sockets and ratchet
3) 2 gaskets from MrT (see diagram below)

Optional but nice to have are:
1) new studs
2) new bolts

Procedure:

Here's a diagram of the entire disassembly process. Please refer to this often:

For more diagrams, check here.

The first step is to put your car on ramps. Remember to have someone always spot you when using ramps. Also, keep your handbrake engaged for more control:


Access to the nuts that need to be removed from underneath the car is hindered by the rear diaper. You will have to remove this with a socket wrench. The screws are easily removed:


You can see the spots where screws need to be removed here:


It is also eases access if you remove the mid-diaper. The screws and poppets that need to be removed are highlighted:


From underneath the car, take a gander at the "3 Amigos", they will be your biggest challenge in this project. Refer back to the diagram to see where this is in. It's in Area 4 in the lower left hand side of the top diagram, near the 2 gaskets:


Use PB Blaster or similar product and drench the 3 Amigos. PB Blaster is cheap, frustration is expensive. Let sit for a couple of minutes (or hours, or days). Using a breaker bar, 12mm DEEP HEX SOCKET, and socket extension, pry the nuts loose by rotating counter clockwise.

It is essential that your socket is HEX shaped, as any other shape will easily make the nut lose it's thread due to the amount of force being applied.

You will need a DEEP SOCKET, as the studs extend past the end of the nut, making it difficult for your socket to have sufficient grip.

You will need a socket extension, as the location of the nut is very difficult to get at (maybe even impossible) without a socket extension.


After removing the 3 Amigos, you will need to remove 2 bolts that brace the manifold to the frame. They are directly to the top of the 3 bolts you just removed. Use PB Blaster to loosen. The left bolt is 14mm, the right is 12mm. There may not be room to use the breaker bar.


You're done with removing the nuts and bolts from underneath the car! Yay! Now to deal with the bolts on top. Pop the lid off the engine bay, and remove the rear strut bars. Instructions for this can be found here:

http://spyderchat.com/forums/index.php?sho...c=44014&hl=

Now to remove the top heat shield, which is held down by 4 bolts. Refer to the 1st diagram, this will be Area 2, top left hand side. You will see 2 bolts. Use PB Blaster to loosen the bolts, and use a 12mm socket and the breaker bar to remove the bolt by rotating counter clockwise:


Refer to Area 6 on the diagram. This is where the last 2 bolts that hold down the heat shield are. Use PB Blaster to loosen the bolts, then remove with a 12 mm socket and ratchet. There will not be enough room for a breaker bar, but the bolts will hopefully give before the bolts lose thread or snap



The heat shield is now loose, but the 02 sensors need to be remove first. Refer back to the diagram. This will be in Area 1. Left side:

Right side:


The 02 sensor harnesses can be disconnected easy, by pressing on the tab to unlock, then pull apart:


Now to remove the 02 sensors. You will need an 02 sensor socket. This is looks like an ordinary socket, with a slit on the side for the sensor wire to pass through:


Soak the 02 sensor in PB Blaster. Wait a couple of minutes. Place the 02 socket on the 02 sensor, passing the wire through the slit, like so:


You can now remove the 02 sensor using a ratchet, or a breaker bar if space allows:


Here's what it looks like removed:


After taking off the other 02 sensor, you're now free to take off the top heat shield:


You've now exposed the manifold! See Area 3 in the diagram on top for reference. There are 5 12mm bolts that connect the manifold to the engine. Use PB Blaster to loosen the bolts. Use 12mm DEEP SOCKETS and the breaker bar to remove the 5 bolts.


Pull out the manifold, and remove the heat shields from it. You're halfway there! Now to re-assemble everything!

 
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#203 ·
<div class='quotetop'>QUOTE (darkday @ Jan 12 2009, 05:19 PM) <{POST_SNAPBACK}></div>
Ok but when you put the goop on remind me what you're doing with that gasket you have on there now again? :p[/b]

Reusing it. :icon_redface:
 
#204 ·
2 ded kittys

Had my 2001 spyder for about 2 weeks now. Was reading about de-badging and fun stuff like that on THIS forum when I read about the pre-cat issue. I HAD heard that issue before, but had been under the impression it was not a big deal until I was "up there" in miles. This forum made me re-think that advice. I have 12,000 miles on a show-room quality silver MR2. It has an extended (third party) warranty for 36K. I decided to kill the pre-cats. I am fairly mechanical, but a recent divorce left me in a condo, so no good garage, and really no good tools. I had never pulled a manifold before. SO, I hired a well-recommended fellow who has done lots of work on toyotas (owns a scion, same engine???) to "hold my hand" and let us use HIS tools and lift. He wound up doing 95% of the "work" but I could certainly do it now. (North colorado mechanic if anyone needs him, just PM me) The entire job took under 3 hours. The 3 amigos came right off with a spash of PB which sat for 3 mins, everything went VERY well. This car, again, is showroom quality, hasnt seen much weather, so corrosion on the bolts was probably a LOT less than normal. The only slow part, and not all that slow even, was gutting the header. Gutted, 6HP shop vac to clean, brushed it inside with a metal brush, blew it out with air hose. Reassembled. Sounds good, SEEMS to run better, not sure on that...wish there was a definitive take on that issue. Oh, used all new gaskets and bolts. Had back-up studs/ bolts from MRT, will return the studs etc which was unused tomorrow. Total (before any return) was 200 for labor and about 70 for ALL parts. No Bombs under the bonnet...NOW is it OK to play with badges and emblems?????? (darkday?)
 
#206 ·
SEEMS to run better, not sure on that
Thank you for taking our advice on the precat thing. No guarantee that you wouldn't have dodged the bullet and been OK, but now we can totally guarantee that your motor will not suffer precat death syndrome. Anything else could happen, but that won't.

Badging and stuff is a plan, but availability of the parts you'll want is the critical issue. See which vendors are selling now and get anything you think you'll ever need. No build can be replicated now, given this problem, so each attempt is a one-off.
 
#208 ·
Six in one hand, half dozen the other. You are accomplishing the same thing either way. If you go with a header swap you won't have to break out the pre-cats from the stock manifold, so it will save a little time. It will also cost more because breaking out the cat material is free, buy a header is not.
 
#209 ·
Six in one hand, half dozen the other. You are accomplishing the same thing either way. If you go with a header swap you won't have to break out the pre-cats from the stock manifold, so it will save a little time. It will also cost more because breaking out the cat material is free, buy a header is not.
Agreed. Personally I say gut the stocker because it's cheaper. I've done both routes and prefer a gutted stock header for sound with my borla exhaust. It's a very minor difference between the two but considering I made money selling my aftermarket header AND improved the sound I'm quite happy. :)
 
#213 ·
Price to gut Pre-Cats

Hello,

Just wondering what is the most I should expect to pay to have my Pre-Cat's gutted and also if the 2 02 sensor that plug into the manifold (I think that's what it is) go bad, will the CEL automatically come on? Sluggish acceleration and I have changed the air filter, spark plugs, oil every 3,000 miles and returned to using 87 fuel. Already changed out the one 02 sensor that plugs in under the car.

Thanks
 
#214 ·
Hello,

Just wondering what is the most I should expect to pay to have my Pre-Cat's gutted and also if the 2 02 sensor that plug into the manifold (I think that's what it is) go bad, will the CEL automatically come on? Sluggish acceleration and I have changed the air filter, spark plugs, oil every 3,000 miles and returned to using 87 fuel. Already changed out the one 02 sensor that plugs in under the car.

Thanks
Since the precats are for emissions, you will have a hard time finding a shop to remove them for you. Do it yourself.
 
#217 ·
I had my precats removed by a very respectable shop, I don't have the right equipment to do that. I was laughed at when I explained the reason and warned about probable o2 sensor errors. Took them 2,5hrs and cost me 65USD (all nuts gaskets etc. were provided by me).
 
#220 ·
This might be an incredibly stupid question, but WTH, I've never let that stop me before. I have a sandblasting cabinet in my garage for my job. Would it be workable or advisable to just stick the manifold in the cabinet and blast the remaining pre-cat media out with glass bead? Glass bead would not harm the interior (I think?) and would throughly remove every iota of pre-cat material. Then a high pressure air blast to clean. What say the sages?
 
#227 ·
Hi all
I know I'm going to get shot down with this but I need to ask! I'd appreciate answers from those who have actually gutted their precats.

So my 3 amigo's loosened relatively easily after soaking and heating.
My top shield bolts are rusted and stuck fast. The heads are very shallow and even my six sided socket is just slipping off them.
The only way I can see them coming off is by doing something extreme like welding an old socket to them or something like that and I don'y even know what state the manifold studs are in yet.

However (here's the stupid question) has anybody considered gutting the precats with the manifold still attached to the engine. If i remove the main cat I'll have clear access to the openings on the bottom of the manifold. There is still room albeit restricted to attack them through the o2 sensor holes and pretty much unrestricted access from the bottom.
I have one of those snake inspection cameras so should be relatively easy to check all the cat material has been removed.
I'm thinking i can still flush it out with a moderate flow of water through the o2 sensor holes.

So is this likely to work?
 
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