Pre-cat damage, how bad is it (photos 2MB in total)

Started by Anonymous, July 14, 2004, 14:51

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Anonymous

July 14, 2004, 14:51 Last Edit: July 14, 2004, 17:53 by Anonymous
I took some pictures of the damaged pre-cat.

The quality of the photos isn't great (a bit like the quality of the CAT).

I'd be interested to know how this damage compares with the failed pre-cats you may have seen... (I'm hoping to hear good news but fear the worst)...

EDITED: Please note that the server isn't sitting behind a 128kb line anymore (so you will won't need to be so patient anymore...    s:wink: :wink: s:wink:  

Close-ups:









The o2 probe from the damaged WU-CAT (Left / cylinders 2 and 3)


o2 probe from undamaged WU-CAT (right / cylinders 1 and 4)


Exhaust exit / tip (with white deposits):


Finally, the manifold overview:


Thanks for your comments and suggestions...

Tem

#1
July 14, 2004, 15:03 Last Edit: January 1, 1970, 01:00 by Tem
Quote from: "phat"Please note that the server is sitting behind a 128kb line (so you will need to be patient...   s:roll: :roll: s:roll:  

Wow...that really was slow  s:shock: :shock: s:shock:  

Anyway, yes, looks just like on other pics. Mine had already collapsed totally when I took a first look in there, so never seen them myself  s:? :? s:?

The O2 sensor looks ok and is probably just fine.

White powder in the exhaust is the cat pieces.

With a little luck, things might still be ok. The major blowup happens when the precats totally collapse. If you can't get it done by Toyota, I'd just get rid of them and see how things develop from there...
Sure you can live without 500hp, but it\'s languishing.

GSB

#2
July 14, 2004, 15:09 Last Edit: January 1, 1970, 01:00 by GSB
[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]

markiii

#3
July 14, 2004, 15:13 Last Edit: January 1, 1970, 01:00 by markiii
enought to be worried, but not somuch that your engine is a definate dod, I'd gut and pray.

any pics from teh bottom of teh manifold.
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 />

Anonymous

#4
July 14, 2004, 15:22 Last Edit: January 1, 1970, 01:00 by Anonymous
Quote from: "markiii"any pics from the bottom of the manifold.

I haven't got that far yet... I really did not expect my pre-cats to be in such dire condition after only 30k miles. Really pissed off at Toyota for fitting such a piece of useless cr*p in my car.

I'll fancy taking the whole exhaust apart this evening to check the extent of the damage but it may be better not to touch anything until the independent expert can assess it (before it's been "tampered" with).

F@@k! And now the weather is @#@@ gorgeous, I've got a new gear box I want to try out desperately, and now I dare not even start the bugger!   s:evil: :evil: s:evil:

Anonymous

#5
July 14, 2004, 17:08 Last Edit: January 1, 1970, 01:00 by Anonymous

GSB

#6
July 14, 2004, 17:49 Last Edit: January 1, 1970, 01:00 by GSB
Quote from: "phat"
Quote from: "GSB"For those of you with no patience, they've been copied here;

http://www.spydermagazine.com/files/phatcat1.jpg
http://www.spydermagazine.com/files/phatcat2.jpg
http://www.spydermagazine.com/files/phatcat3.jpg
http://www.spydermagazine.com/files/phatcat4.jpg
http://www.spydermagazine.com/files/phatcat5.jpg
http://www.spydermagazine.com/files/phatcat6.jpg
http://www.spydermagazine.com/files/phatcat7.jpg
http://www.spydermagazine.com/files/phatcat8.jpg

Cheers GSB, I've posted a message with these (much faster) links on SC too. Hope you don't mind the extra bandwidth usage.

No problem, might be good to edit your original post to include them as well?
[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

#7
July 14, 2004, 17:54 Last Edit: January 1, 1970, 01:00 by Anonymous
Quote from: "GSB"No problem, might be good to edit your original post to include them as well?

Done!

Anonymous

#8
July 14, 2004, 19:55 Last Edit: January 1, 1970, 01:00 by Anonymous
I don't understand.  Your precats don't look at all like mine (from a 2003 US model) did when I took off my header at 10-15,000 miles.  There are pics of mine somewhere on SC (sorry, not very helpful there).  I could clearly see holes arranged in a grid.  Yours look like they are totally blocked up.  This does not compute.

EDIT: I did a pretty thorough search on SC and could not find my pictures.  I have them at home, however.  Will post here if necessary.

Slacey

#9
July 14, 2004, 21:30 Last Edit: January 1, 1970, 01:00 by Slacey
Quote from: "Beanie"I could clearly see holes arranged in a grid.  Yours look like they are totally blocked up.  This does not compute.
Well spotted Beanie... mine and all the others were like yours, ie. the honeycomb was hollow and you could see light through the matrix.
Ex 2002 Black / Red Leather Hass Turbo

Bongo

#10
July 14, 2004, 21:51 Last Edit: January 1, 1970, 01:00 by Bongo
Maybe the photo has been taken so it doesn't look straight down the honeycomb?

SteveJ

#11
July 14, 2004, 22:01 Last Edit: January 1, 1970, 01:00 by SteveJ
Looking through the O2 holes you cannot get directly over the honeycomb - the only way to see through it is to look from underneath - hence it looks blocked in the photo's

Anonymous

#12
July 14, 2004, 22:08 Last Edit: January 1, 1970, 01:00 by Anonymous
SteveJ is right, but I saw circular openings inside each square, but not the grid itself.  I guess when the precat goes, what is inside the grid goes, then the grid/matrix itself begins to collapse.  Those babies are toast.  Hopefully you caught it soon enough.

Anonymous

#13
July 15, 2004, 02:13 Last Edit: January 1, 1970, 01:00 by Anonymous
A reasonably healthy precat, viewed from bottom.

Anonymous

#14
July 15, 2004, 17:17 Last Edit: January 1, 1970, 01:00 by Anonymous
Mine looks the same, except that there is a fine crack going right through it:



More photos (sorry about the slow link... it's a kind of retro surfing experience...)

http://www.hanneken.net/MR2/precat/under2.jpg

http://www.hanneken.net/MR2/precat/under3.jpg

Unfortunately, most of the desintegration took place on the engine facing side.

I'm going to get the engine checked by an independent expert. I guess they will do a chemical analysis of the engine oil (check for traces of ceramic material), check the compression levels (if cylinders 3 and 4 are much different from the other two, that would be a sign of damage I guess). Perhaps they could use an endoscope or something similar to check the surface of the cylinders for scoring?

I guess I will find out if the engine is dying or not...

Anonymous

#15
July 16, 2004, 20:29 Last Edit: January 1, 1970, 01:00 by Anonymous
Pics of mine, out now!  No prob before but I think it's time!




Anonymous

#16
July 17, 2004, 01:37 Last Edit: January 1, 1970, 01:00 by Anonymous
Spoke to an independent expert today about the problem. He told me he hadn't seen or heard of anything like this before. Essentially because these types of pre-cats are still relatively rare. (However, collapsing ceramic *main* CATs are apparently very common according to him.)

He wasn't convinced the ceramic particles could have already entered the engine, since there isn't any classic exhaust gas recirculation system. However the main cat could already be affected by some debris. (I found a few fine debris at the entrance of the main cat.) He reckons that engine damage will only occur once the main cat is completely blocked (following a total collapse of one or all of the pre-cats) causing very high back end pressure.

If this is true, my engine could still be 100% OK. After all I haven't noticed any loss of power or excessive oil consumption. However, I don't want to get my hopes too high... In any case, I'm going to get the engine checked thoroughly next week.

My only concern is that to test the engine I may need to re-install the manifold and run the engine with the dodgy pre-cats in it  s:roll: :roll: s:roll:  

My advice to all ZZW30 owners out there (in particular those of you who don't have a warranty): check your pre-cats regularly and at any sign of deterioration, gut them out!   s:wink: :wink: s:wink:

Tem

#17
July 17, 2004, 11:56 Last Edit: January 1, 1970, 01:00 by Tem
Quote from: "phat"He wasn't convinced the ceramic particles could have already entered the engine, since there isn't any classic exhaust gas recirculation system.

Well...the pre cats are right by the exhaust valves and being just a fine dust, they will go with the flow, not just fall down. The exhaust valves aren't really a one way street, though it's usually easy to think about engines that way. But in reality the exhaust valves are still open during early intake stroke and some exhaust fumes from manifold will get in the cylinder.

So it's very possible. It might be that the dust doesn't get sucked back in before it totally collapses, I don't think anyone knows that for sure.  s:? :? s:?
Sure you can live without 500hp, but it\'s languishing.

Anonymous

#18
July 17, 2004, 12:36 Last Edit: January 1, 1970, 01:00 by Anonymous
Quote from: "Tem"
Quote from: "phat"He wasn't convinced the ceramic particles could have already entered the engine, since there isn't any classic exhaust gas recirculation system.

Well...the pre cats are right by the exhaust valves and being just a fine dust, they will go with the flow, not just fall down. The exhaust valves aren't really a one way street, though it's usually easy to think about engines that way. But in reality the exhaust valves are still open during early intake stroke and some exhaust fumes from manifold will get in the cylinder.

So it's very possible. It might be that the dust doesn't get sucked back in before it totally collapses, I don't think anyone knows that for sure.  s:? :? s:?

Well Tem, I must have been over-optimistic, but reality came back with a bang when I read Toyota's official "MR2 New Car Features" in which they explain very clearly how the VVT-i system operates. (p.41-44.) IIRC you also have that excellent book.

Well, here is just a quote from the table of operation states: "At medium load" - "Increasing overlap to increase internal EGR for pumping loss elimination" - "Better fuel economy. Improved emission control"

In fact, overlap (for internal EGR) takes place at just about all operating states except during idling; at low temperatures; and upon starting/stopping the engine.

So in effect, this is official Toyota evidence that ceramic particles from a collapsing pre-cat (or warm-up CAT or front CAT - whatever Toyota wants to call them) can enter the cylinders; especially if the main cat is blocked as the difference in pressure between exhaust and intake will be massive.

I'm starting to wonder if Toyota isn't using the MR2 Roadster as a "test bed" for this new technology... A relatively low production car (to minimise the risk of damaging their reputation if this car gets a bad name on reliability); a type of car that will be driven "hard" (not like your average Yaris driven by mum).

My wife being in New Product Development for a very large company, I have heard of cases similar to this. After all, the Toyota engineers who designed the engine and the pre-cats must be completely aware of the potential risk/problems. If they feel the technology isn't 100% safe for say a "normal lifespan" (e.g. 100k miles), they will not use them on the mass produced models. Not until the technology has been made reliable enough.

Well, all I can do now is wait until the engine gets checked out... But I'm a wee bit less optimistic now.   s:( :( s:(

Tem

#19
July 17, 2004, 13:20 Last Edit: January 1, 1970, 01:00 by Tem
Ah, I didn't know they call it internal EGR...


Quote from: "phat"I'm starting to wonder if Toyota isn't using the MR2 Roadster as a "test bed" for this new technology...

I'm sure they are for the reasons you said  s:? :? s:?  Test data from thousands of cars around the world is surely better than a ten or hundred cars in Japan. Somehow I feel the same about SMT, I'm sure Toyota will offer it for more popular models in future.
Sure you can live without 500hp, but it\'s languishing.
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