Precat removal - How I did it...

Started by GSB, April 14, 2004, 09:10

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Anonymous

#25
Yeah, you're right there Mark. A family member was bitten by something similar with household appliances. I temd to be VERY careful of what these things cover nowadays.......checking both MrT's and the AA's extended warranties and won't bother with either if they don't cover that kind of thing. Thanks for the reminder........  s:D :D s:D

Anonymous

#26
beginning to wonder if i dare drive my car after reading all this

markiii

#27
drive it, enjoy it.

take what pre-cautions you can, and if it does go, it's not earth shattering money to fix.

mine gets redlined regularly thst what I bought t for and thats how it gets driven.

If it all goes the way of the pear such is life.
Gallardo Spyder<br />Ex Midnight Blue 911 T4S<br />EX VXR220<br />Ex Custom Turbo 2001 Sahara Sun MR2 Roadster 269bp, 240lbft<br /><br />MR2ROC Committee 2002 - 2009<br /><br />

GSB

#28
Quote from: "markiii"drive it, enjoy it.

take what pre-cautions you can, and if it does go, it's not earth shattering money to fix.

mine gets redlined regularly thst what I bought t for and thats how it gets driven.

If it all goes the way of the pear such is life.

Couldn't agree more. This is by no means a new problem, but its one you can manage with additional maintenance checks. Its not the end of the earth if it does go bang, but if you carry out some regular inspections, you'll at least have the oppertunity to avert disaster at some point in the future, and save yourself a few hundred quid into the bargain... Otherwise, its business as usual...
[size=50]Ex 2001 MR2 Roadster in Silver
Ex 2004 Facelift MR2 Roadster in Sable Grey
Ex 2007 Mazda 6 MPS in Mica Black
Current 2013 Mazda MX5 2.0 \'Venture Edition\' Roadster Coupe in Brilliant Black[/size]

Anonymous

#29
Beginning to think your way Mark!!! I didn't buy the thing to worry about it going bang. I bought it cos I knew the Mk1s were good (shame about the Mk2s) and I fancied something I could thrash around. Drive it mate. Worry about it later...........

loadswine

#30
Excellent report Grant, I have now got the necessary tool and will check on my precats this weekend for the first time 30k and out of warranty,its fairly certain they are destined for the bin. Just a little question: you don't mention any new gaskets or seals , did you replace them as a matter of course or was it not needed.
Whether folks agree with the procedure or not ,its about sharing information and experience.Thanks man.
No Roadster any more, Golf 7.5 GTi Performance

Anonymous

#31
That is a brilliant write up, after reading all this i would definately give it a go. After all once the warrenty is up you are on your own. Im sure if i bugger it up i can source another manifold.
Well worth doing i feel, simply erasing one component that could cause big problems.

Excellent...

GSB

#32
Quote from: "loadswine"Just a little question: you don't mention any new gaskets or seals , did you replace them as a matter of course or was it not needed.

Its good engineering practice to use new gaskets each time a joint is broken, and ordinarily I would do just that. I didn't this time purely because It was a fairly urgent job, and I know that Hayward & Scott didn't when they worked on my car last year. However I am going to put in new gaskets at the manifold to main cat joint, because I think it might be leaking... Or it might be that my ears are being unusually paranoid and hearing every single little noise that the engine makes  s:wink: :wink: s:wink:  I cant actually find any evidence of a leak though, so its probably not really needed. Just dotting the i's and crossing the t's I guess...  s:roll: :roll: s:roll:
[size=50]Ex 2001 MR2 Roadster in Silver
Ex 2004 Facelift MR2 Roadster in Sable Grey
Ex 2007 Mazda 6 MPS in Mica Black
Current 2013 Mazda MX5 2.0 \'Venture Edition\' Roadster Coupe in Brilliant Black[/size]

mrsmr2

#33
Worrying reading for someone thinking of buying a new one.

Do we have any experience of Toyota's reaction if the pre cats were showing degradation during the warranty period?

My concern is if I do 20k miles in years 1 and 2, and the pre-cats start breaking up, the engine would probably go after the warranty period.  Would Toyota act during the warranty period (replacing the pre-cats) or would they refuse to accept it as a problem?
04 Astral Black, hard top, air con, black leather, Corky\'s MSMB; FSB;  RMB; RLCB, empty exhaust manifold, cg-lock.  Warranty: new wheels @ 20k, new pads and discs @ 21k, new wheels @ 26.4k

Anonymous

#34
sorry to be simple but i thought that the cats were on the exhaust side of the engine not on the intake side so how does the pre cat break up get into the inlet side and  go into the bores and damage them.ok on a turbo the exhaust gasses are recirculated but not on a normal asperated engine.  s:?: :?: s:?:

Tem

#35
Quote from: "dsr"sorry to be simple but i thought that the cats were on the exhaust side of the engine not on the intake side so how does the pre cat break up get into the inlet side and  go into the bores and damage them.

Please check the thread called "How does broken pre-cat get into bores?"
Sure you can live without 500hp, but it\'s languishing.

markiii

#36
Quote from: "mrsmr2"Worrying reading for someone thinking of buying a new one.

Do we have any experience of Toyota's reaction if the pre cats were showing degradation during the warranty period?

My concern is if I do 20k miles in years 1 and 2, and the pre-cats start breaking up, the engine would probably go after the warranty period.  Would Toyota act during the warranty period (replacing the pre-cats) or would they refuse to accept it as a problem?

once they start to go they go quick.  if you can show them a problem within warranty they have to fix it.
Gallardo Spyder<br />Ex Midnight Blue 911 T4S<br />EX VXR220<br />Ex Custom Turbo 2001 Sahara Sun MR2 Roadster 269bp, 240lbft<br /><br />MR2ROC Committee 2002 - 2009<br /><br />

mrsmr2

#37
It's seems that the only way to truly check is to remove the exhaust.
Therefore, if Toyota found out someone had been removing and checking the pre cat on regular basis, would they pass the blame on - a la "I think you must have dropped it sir", or would they be reasonable about it?
04 Astral Black, hard top, air con, black leather, Corky\'s MSMB; FSB;  RMB; RLCB, empty exhaust manifold, cg-lock.  Warranty: new wheels @ 20k, new pads and discs @ 21k, new wheels @ 26.4k

SteveJ

#38
Quote from: "mrsmr2"It's seems that the only way to truly check is to remove the exhaust.
Therefore, if Toyota found out someone had been removing and checking the pre cat on regular basis, would they pass the blame on - a la "I think you must have dropped it sir", or would they be reasonable about it?

The part of the pre-cat that we are interested in is only visible through the O2 hole, so there is no need to remove any part of the exhaust - just the O2 sensor.

Anonymous

#39
I recently gutted mine.  Check this out for further opionions http://www.spyderchat.com/phpBB/viewtopic.php?t=46,

As far as I'm concerned this procedure is a must-do.  And I'm not immensely mechanically inclined either.  The hardest part is just reaching some of the upper manifold bolts, and breaking some heavily rusted lower bolts.  Thanks GSB for this concise "how to".  And thanks to Spyderchat for the warnings.

As for performance afterwards maybe it feels faster and is clearly a little louder (throatier) under throttle.  If you look at the removed honeycombed remains of the precats they obviously have to have some sort of restriction.  And if you feel how brittle it is you wonder how it could survive the exhaust pressure along with sportscar jarring for any period of time.  This was a Toyota mistake.

mrsmr2

#40
Under the post "Buying second hand HOW DO I" - it says
"you can get a fair idea, on someones drive by getting an 02 tool, 22mm and a ratchedt. pop the o2 sensor out and shine a torch in.

this won't tell you if there is damage to the bottom of the cat, but thats a drop the downpipe job.

It will however mean that if you see a great hole you may want to pass on that particular car.
"

I interpret this as meaning that doing a proper check requires the removal of the full pre cat assembly.

Am I correct or is the removal of the O2 sensor sufficient?

Thanks

Jason
04 Astral Black, hard top, air con, black leather, Corky\'s MSMB; FSB;  RMB; RLCB, empty exhaust manifold, cg-lock.  Warranty: new wheels @ 20k, new pads and discs @ 21k, new wheels @ 26.4k

GSB

#41
Removing the 02 sensor gives you access to the upper side of the precats. Pieces broken loose here are the pieces that will be sucked into the engine. If something breaks away from the lower side of the cat then its more likely to migrate down to the main cat, where it has the potential to cause a blockage and not much else. This is still bad, but nothing like as bad as having lumps of the stuff floating around in your cylinders. Arguably then, its the upper side we're more interested in, as it's exposed to the greater mechanical and thermal stresses, and has the potential to cause the most damage in the shortest amount of time.

I found that when my cats started to go the lower side was like new, with only the upper side showing signs of degrading.
[size=50]Ex 2001 MR2 Roadster in Silver
Ex 2004 Facelift MR2 Roadster in Sable Grey
Ex 2007 Mazda 6 MPS in Mica Black
Current 2013 Mazda MX5 2.0 \'Venture Edition\' Roadster Coupe in Brilliant Black[/size]

mrsmr2

#42
Thanks, that is much clearer now.

Excellent information by the way.

Jason
04 Astral Black, hard top, air con, black leather, Corky\'s MSMB; FSB;  RMB; RLCB, empty exhaust manifold, cg-lock.  Warranty: new wheels @ 20k, new pads and discs @ 21k, new wheels @ 26.4k

Anonymous

#43
just noticed on that spyderchat thread that some guy is on his FIFTH engine - talk about being unlucky!!

do you think it could be down to the lower octane fuel they use over there that's braking up the cats?

Tem

#44
Quote from: "Tomr2"just noticed on that spyderchat thread that some guy is on his FIFTH engine - talk about being unlucky!!

do you think it could be down to the lower octane fuel they use over there that's braking up the cats?

When I read those, it seemed like the dealer tried to replace as little as possible...only causing the same to happen again. I don't remember anyone actually going through several engines, if the dealer replaced the whole engine, manifold and cat...
Sure you can live without 500hp, but it\'s languishing.

loadswine

#45
I checked on my precats yesterday and to my amazement! found that there was no sign of deterioration of the matrix visible. I had a really good look and was a little concerned at first when I saw that they were not completely flat across the surface and did ,in fact have a slightly dished shape in the central area. First I thought PANIC, but when I checked both sides I noticed that this shape seemed to be there on purpose to allow for the O2 sensors to sit close up to the surface of the honeycomb. Please tell me I'm right or my car has immediate surgery.  s:x :x s:x
No Roadster any more, Golf 7.5 GTi Performance

Anonymous

#46
the monkey is now (pre) catless, MAF sensor cleaned and ECU reset - the 2 is now a different car   s:D :D s:D  
just to say thanks for the write up and hey if a monkey can do it anyone can  s:lol: :lol: s:lol:

GSB

#47
Quote from: "loadswine"I checked on my precats yesterday and to my amazement! found that there was no sign of deterioration of the matrix visible. I had a really good look and was a little concerned at first when I saw that they were not completely flat across the surface and did ,in fact have a slightly dished shape in the central area. First I thought PANIC, but when I checked both sides I noticed that this shape seemed to be there on purpose to allow for the O2 sensors to sit close up to the surface of the honeycomb. Please tell me I'm right or my car has immediate surgery.  s:x :x s:x

Thats a new one on me. As new mine were completely flat. No dishing or anything.
[size=50]Ex 2001 MR2 Roadster in Silver
Ex 2004 Facelift MR2 Roadster in Sable Grey
Ex 2007 Mazda 6 MPS in Mica Black
Current 2013 Mazda MX5 2.0 \'Venture Edition\' Roadster Coupe in Brilliant Black[/size]

Anonymous

#48
I'm sure that manifold i had looked like the pre cats were slightly dished, by this i mean the centre looked higher than the sides, convex rather than concave.(i think)

If you have mine yet, take a look at it and see can you?

GSB

#49
For your information:

The manifold to main cat gaskets are really non-reusable items, they seem to be held in stock by most main dealers, and at teh grand total of £5.22 for a pair, its a worthwhile investment.


Part number is T90917-06065
[size=50]Ex 2001 MR2 Roadster in Silver
Ex 2004 Facelift MR2 Roadster in Sable Grey
Ex 2007 Mazda 6 MPS in Mica Black
Current 2013 Mazda MX5 2.0 \'Venture Edition\' Roadster Coupe in Brilliant Black[/size]