Pre Cat Removal - Should I / Shouldn't I
Discussion
I know it's most likley been done before but I see no harm in getting the latest upto date opinions good or bad from everyone.
At the mo I've taken the exhaust manifolds off my 29,000 mile Chim 500 to replace the gaskets (and now the mounts due to heat damage, see pics) and would just like people's opinions on whether to remove the pre cats (manifold cats)or leave them in.
As you can see from the pics, the cats are a nice clean greyish white colour and in an unblocked condition, but I'd just like to know if there is any advantage / benifits in removing them now, or, due to their condition, should I just wait until the gaskets need replacing in the future and review it then.
If the general concensus (sp) is to remove them
, then how long / how much and what's involved in removing them and is it worth putting in non reversal cones? and once again how long / how much and what's involved?
A further point as the exhaust is off, I was looking at having the exhaust sleeved / cherry bombed so would it just be worth leaving the pre cats in as it wouldn't make much difference in achieving aural extasy.
ps - I'm not looking at a full ear bleeding sleeved through pipe de cat.
Many thanks.
Craig
pps - is it me, or is it a nightmare to clean up the manifold faces. Any tips?
>> Edited by crazycraig on Thursday 15th December 11:01
At the mo I've taken the exhaust manifolds off my 29,000 mile Chim 500 to replace the gaskets (and now the mounts due to heat damage, see pics) and would just like people's opinions on whether to remove the pre cats (manifold cats)or leave them in.
As you can see from the pics, the cats are a nice clean greyish white colour and in an unblocked condition, but I'd just like to know if there is any advantage / benifits in removing them now, or, due to their condition, should I just wait until the gaskets need replacing in the future and review it then.
If the general concensus (sp) is to remove them
, then how long / how much and what's involved in removing them and is it worth putting in non reversal cones? and once again how long / how much and what's involved? A further point as the exhaust is off, I was looking at having the exhaust sleeved / cherry bombed so would it just be worth leaving the pre cats in as it wouldn't make much difference in achieving aural extasy.
ps - I'm not looking at a full ear bleeding sleeved through pipe de cat.
Many thanks.
Craig
pps - is it me, or is it a nightmare to clean up the manifold faces. Any tips?
>> Edited by crazycraig on Thursday 15th December 11:01
The plugs are just screwed back in to plug the holes.
I put my hand into the manifold and checked for security of the cat and it feels well stuck in there.
As I said, I don't realy want to create extra work by removing the cats if it's of no benifit, especially as 'to me' they look in fairly good nick.
Still abit worried though about how smooth you should get the faces of the manifolds, the engine end is fine, but the manifolds aren't that great, even after using wire wool, then a wire brush, then a wire brush on drill and then finally a file. Maybe it's not so important when using a material gasket but as I was planning on putting on the later steel gaskets (part no ERR6733) I guess it's crucial! (or should I just slap on more exaust sealant?)
Craig
I put my hand into the manifold and checked for security of the cat and it feels well stuck in there.
As I said, I don't realy want to create extra work by removing the cats if it's of no benifit, especially as 'to me' they look in fairly good nick.
Still abit worried though about how smooth you should get the faces of the manifolds, the engine end is fine, but the manifolds aren't that great, even after using wire wool, then a wire brush, then a wire brush on drill and then finally a file. Maybe it's not so important when using a material gasket but as I was planning on putting on the later steel gaskets (part no ERR6733) I guess it's crucial! (or should I just slap on more exaust sealant?)
Craig
Thanks Guys. 
Gutted about my steel gaskets, there's another 8 quid down the drain, but then again, better to know now as I wouldn't want to be removing manifolds very often as it's a pain in the ar*e.
Interesting comments about the heat generated due to the cats, but thinking about how much resistance is there, I can believe it.
As I've said earlier, I've now got to replace the damaged engine mounts before the manifolds go back on so I'll have abit more time to get some of these composite gaskets and the correct size lamda sensor removal tool. Just had one delivered from [url]www.ccw-tools.co.uk/catalogue/product.asp?prod_id=2893&cat_id=81[/url] and found out 22mm it's to bloody big......Tuh
It was also mentioned about not to get the other mod (cherry bombs) done to the exhaust until the pre-cats are out due to the noise. Is there a reason for this?
I thought by taking out the pre-cats there wouldn't be much increase in the noise.
Finally, what's the crack with these cones?
>> Edited by crazycraig on Friday 16th December 09:12
Gutted about my steel gaskets, there's another 8 quid down the drain, but then again, better to know now as I wouldn't want to be removing manifolds very often as it's a pain in the ar*e.
Interesting comments about the heat generated due to the cats, but thinking about how much resistance is there, I can believe it.
As I've said earlier, I've now got to replace the damaged engine mounts before the manifolds go back on so I'll have abit more time to get some of these composite gaskets and the correct size lamda sensor removal tool. Just had one delivered from [url]www.ccw-tools.co.uk/catalogue/product.asp?prod_id=2893&cat_id=81[/url] and found out 22mm it's to bloody big......Tuh
It was also mentioned about not to get the other mod (cherry bombs) done to the exhaust until the pre-cats are out due to the noise. Is there a reason for this?
I thought by taking out the pre-cats there wouldn't be much increase in the noise.
Finally, what's the crack with these cones?
>> Edited by crazycraig on Friday 16th December 09:12
Hi Paul.
The pre-cats or manifold cats are the ones I'm talking about.
I wouldn't dream of consider myself as being in the same league as a full time mechanic, but I'm fairly competant with a set of spanners and 8 hrs sounds to be a fair time for someone at my level, 1 hr per manifold to remove, 1 hr per manifold to remove the cats, 1hr per manifold to put back on and 2 hrs for cleaning, filing, swearing, cursing, struggling and putting on plasters where you rip you hands and forearms to shreads, so 8 hrs (or a days work) for a mech is doable, especially with a post lift, but at a cost of £200.00, it sounds well worth it, I'd hate to imagine what a cuffufel I'd be in if I'd have sheared off a bolt or 2.
Anyway, comments taking in about having the non reversal cones fitted, the exhaust mod and how the look of a cat doesn't nescisarilly mean it's not blocked, so a de cat with non reversal cones maybe the way to go ?????
So just the gaskets to deal with.(oh, and the exhaust mounts and the refiting of the manifolds)
I've posted another pic below of the ones I've got at the mo and the hole in them are the same size as the manifold ports.
I've looked at other topics and people seemed to have used them no bother so I think I'd better give ACT or V8D a ring just to check.
The pre-cats or manifold cats are the ones I'm talking about.
I wouldn't dream of consider myself as being in the same league as a full time mechanic, but I'm fairly competant with a set of spanners and 8 hrs sounds to be a fair time for someone at my level, 1 hr per manifold to remove, 1 hr per manifold to remove the cats, 1hr per manifold to put back on and 2 hrs for cleaning, filing, swearing, cursing, struggling and putting on plasters where you rip you hands and forearms to shreads, so 8 hrs (or a days work) for a mech is doable, especially with a post lift, but at a cost of £200.00, it sounds well worth it, I'd hate to imagine what a cuffufel I'd be in if I'd have sheared off a bolt or 2.
Anyway, comments taking in about having the non reversal cones fitted, the exhaust mod and how the look of a cat doesn't nescisarilly mean it's not blocked, so a de cat with non reversal cones maybe the way to go ?????
So just the gaskets to deal with.(oh, and the exhaust mounts and the refiting of the manifolds)
I've posted another pic below of the ones I've got at the mo and the hole in them are the same size as the manifold ports.
I've looked at other topics and people seemed to have used them no bother so I think I'd better give ACT or V8D a ring just to check.
David H said:
This socket does the trick:
www.tooled-up.com/Product.asp?PID=123278
Pull off the plastic protector, grind or cut a slot down it for the wire and bob's your uncle.
Or try this one - www.ccw-tools.co.uk/catalogue/product.asp?prod_id=5233&cat_id=81 from these people.
Come highly recommended, especially from me as I've bought most of my tools from them and 30% cheaper.
I order most things before 3 and have it on standard delivery and still get woke up by posty the next morning banging on the door at 0730hrs.
Shouldn't moan, at least they deliver prompt. As for the heat, I've spoke with a few people today on this subject and they all mention how the heat doesn't drop in the sense, it just moves more forward from the manifolds towards the main cat, which in turn can have effect on the main cat by breaking it down quicker and at worst, cause it to come free and drop to the bottom of the dustbin (housing) that it's in.
>> Edited by crazycraig on Friday 16th December 16:06
Thanks everyone.
Just to keep you all upto date, spoke with Shaune at V8 Developments (great guy, very helpful) and explained about the thread and the issue with the gaskets and how they were the same size as the head and manifold.
For a moment I thought I'd opened up a can of worms when he told me he thought that the gaskets that I have (part no ERR6733) were for a smaller V8 lump and wouldn't fit a 5 ltr worked head, (unless I've got a different head and manifold) but he'd never came across it yet.
So as the nice chap that he is, he clicked onto everyones fav site, and checked out the photos and could tell instantly that I had the correct head and that if the gasket opening is the same size as the opening on heads then they would be suitable.
Once again, the power of Pistonheads comes up trumps.
Craig
Just to keep you all upto date, spoke with Shaune at V8 Developments (great guy, very helpful) and explained about the thread and the issue with the gaskets and how they were the same size as the head and manifold.
For a moment I thought I'd opened up a can of worms when he told me he thought that the gaskets that I have (part no ERR6733) were for a smaller V8 lump and wouldn't fit a 5 ltr worked head, (unless I've got a different head and manifold) but he'd never came across it yet.
So as the nice chap that he is, he clicked onto everyones fav site, and checked out the photos and could tell instantly that I had the correct head and that if the gasket opening is the same size as the opening on heads then they would be suitable.
Once again, the power of Pistonheads comes up trumps.
Craig
LATEST UPDATE
Right, got home on Friday and found out I was wrong
. The gaskets as shown, are to small for a 5 ltr head by about 2-3mm, so I guess I'll be giving ACT or V8D a ring for some composites.
Iv'e cleaned up the surfaces of the manifolds and heads with no damage / scoring so all's well.
As for the cats, they're now gone. I started off by getting an old long reach spartplug box spanner and cut a hole in it 100mm up it and cut a slot out the side. I then opened the end out so it fit around the lamda and hey presto
a .99p lamda sensor removal tool. Yes I suppose a nice socket would have been better, but as the grinder was at work I didn't want to be cutting away at a socket for the next 3 hrs with a hacksaw.
Next came the removal of the cats and I can say it is a pain. Mine were fairly well stuck in but I found by putting around 10 small pilot holes with a 450mm long possi drive and then going at it with a 10mm SDS drill bit on hammer soon gets them out, well........soon as being and hour each.
As you can see, the cats themselves are made of a radiator matrix type material except very tightly packed, so I can see why it would make the exhaust alot more free flowing and reduce the back pressure..............aw well, to late now.
I then cut down a cheap wire brush and put it inside the manifold where the cat was and cleaned up the inside surface as I was left with the od bit of vain still stuck to the inside surface and dont fancy them coming loose in the future and geting blown into the main cat and plugging that up.
Guess now it's just a case of putting the manifold back on and seeing what it sounds like. (hopefully minus the ticking)
>> Edited by crazycraig on Monday 19th December 09:02
Right, got home on Friday and found out I was wrong
. The gaskets as shown, are to small for a 5 ltr head by about 2-3mm, so I guess I'll be giving ACT or V8D a ring for some composites. Iv'e cleaned up the surfaces of the manifolds and heads with no damage / scoring so all's well.
As for the cats, they're now gone. I started off by getting an old long reach spartplug box spanner and cut a hole in it 100mm up it and cut a slot out the side. I then opened the end out so it fit around the lamda and hey presto
a .99p lamda sensor removal tool. Yes I suppose a nice socket would have been better, but as the grinder was at work I didn't want to be cutting away at a socket for the next 3 hrs with a hacksaw. Next came the removal of the cats and I can say it is a pain. Mine were fairly well stuck in but I found by putting around 10 small pilot holes with a 450mm long possi drive and then going at it with a 10mm SDS drill bit on hammer soon gets them out
, well........soon as being and hour each. As you can see, the cats themselves are made of a radiator matrix type material except very tightly packed, so I can see why it would make the exhaust alot more free flowing and reduce the back pressure..............aw well, to late now.
I then cut down a cheap wire brush and put it inside the manifold where the cat was and cleaned up the inside surface as I was left with the od bit of vain still stuck to the inside surface and dont fancy them coming loose in the future and geting blown into the main cat and plugging that up.
Guess now it's just a case of putting the manifold back on and seeing what it sounds like. (hopefully minus the ticking)
>> Edited by crazycraig on Monday 19th December 09:02
To be honest.......no difference when running in the garage, but then I haven't had the car out on the road so it may sound different when under load.
I got the exhaust back on Wednesday from having it sleeved and temporarily fitted it last night, and it sounds quite different now.
Didn't realy give it some as I only put the manifolds back on the other day but it definatley sounds lounder and on tick over the note has changed from a deep drone to more of a deep glug, glug, glug noise.
Not sure if it'll change over time as it beds in, maybe someone could advise?
Craig
I got the exhaust back on Wednesday from having it sleeved and temporarily fitted it last night, and it sounds quite different now.
Didn't realy give it some as I only put the manifolds back on the other day but it definatley sounds lounder and on tick over the note has changed from a deep drone to more of a deep glug, glug, glug noise.
Not sure if it'll change over time as it beds in, maybe someone could advise?
Craig
Yes.
I cut the box open, removed all the packing (quite like horsehair), cut out the original pipes (which have holes in) and had some solid pipes welded in their place, then repacked and had it welded shut. All in all a couple of hours works.
As for getting deeper.
I've already had most of the neigbours looking out to see what's causing their windows to vibrate and setting off their car alarms.
Guess I'll be Mr Popular in the summer when I go out for those early morning runs.
Great. I can't wait.
I cut the box open, removed all the packing (quite like horsehair), cut out the original pipes (which have holes in) and had some solid pipes welded in their place, then repacked and had it welded shut. All in all a couple of hours works.
As for getting deeper.
I've already had most of the neigbours looking out to see what's causing their windows to vibrate and setting off their car alarms.
Guess I'll be Mr Popular in the summer when I go out for those early morning runs.
Great. I can't wait.
Must admit....................I wasn't quite sure if I should go for both and the missus didn't want it done at all as she likes the original exhaust note.
It started off by having the old ticking noise and a black soot mark from the manifold gasket so I had to have them replaced, with dealers wanted between 2-4 hrs per side for what is a fairly straight forward job, if you can get access to below as well as above and have a selction of different profile spanners to make it easier.
I decided to do one side at a time as I wasn't to confident that if I took off both sides and the exhaust I get it all to line up with the Y piece correctly. Off side I found the easiest, albeit bottom number 8 (above starter motor) is a little sh*t, with the near side alot easier, as you remove the exhaust to get access to the bottom and there's also abit more room to undo the top bolts when the AFM is removed.
After removing the manifold, cleaning off the surfaces I was time to look at the options. The cat looked in good shape, and I was quite happy to leave it in as I wanted to try to keep the car original, but as was said earlier, 'just cos it looks good, it doesn't mean it's not blocked or coked up inside'. That, the fact that it so say does not adversly effect the system by removing them and you wouldn't know by looking that they have been removed, then I though what the hell.
I knocked/SDS drilled them out and put the manifolds back on the car, run up to temp a few times and rechecked / tightened the bolts each time.
As said, personnaly I didn't notice any difference from before to after so I then decided as the exhaust was only temporarily connected to the car by the clamp at the front I'd take it off and have it sleeved.
Now it's done though, I'm more than happy and even the wife, who said she would be honest, thinks it sounds great, with the pair of us spending most of Sunday afternoon getting carbon monoxide poisoning by crouching down behind the car while the otherone blips the throttle, with both of us having silly grins on our faces and doing thumb up gestures to each other while the neighbours stare out their windows in disgust...........F'ing Great.
I haven't had the car on the road yet so am not sure about the new volumn or tone, but from what I've heard already..............it 'will' be worth it.
Worst case.................on a long journey and it gets to much.........We'll just have to look a pair of t*ts and wear ear defenders, but it'll still be worth it.
>> Edited by crazycraig on Tuesday 10th January 12:30
It started off by having the old ticking noise and a black soot mark from the manifold gasket so I had to have them replaced, with dealers wanted between 2-4 hrs per side for what is a fairly straight forward job, if you can get access to below as well as above and have a selction of different profile spanners to make it easier.
I decided to do one side at a time as I wasn't to confident that if I took off both sides and the exhaust I get it all to line up with the Y piece correctly. Off side I found the easiest, albeit bottom number 8 (above starter motor) is a little sh*t, with the near side alot easier, as you remove the exhaust to get access to the bottom and there's also abit more room to undo the top bolts when the AFM is removed.
After removing the manifold, cleaning off the surfaces I was time to look at the options. The cat looked in good shape, and I was quite happy to leave it in as I wanted to try to keep the car original, but as was said earlier, 'just cos it looks good, it doesn't mean it's not blocked or coked up inside'. That, the fact that it so say does not adversly effect the system by removing them and you wouldn't know by looking that they have been removed, then I though what the hell.
I knocked/SDS drilled them out and put the manifolds back on the car, run up to temp a few times and rechecked / tightened the bolts each time.
As said, personnaly I didn't notice any difference from before to after so I then decided as the exhaust was only temporarily connected to the car by the clamp at the front I'd take it off and have it sleeved.
Now it's done though, I'm more than happy and even the wife, who said she would be honest, thinks it sounds great, with the pair of us spending most of Sunday afternoon getting carbon monoxide poisoning by crouching down behind the car while the otherone blips the throttle, with both of us having silly grins on our faces and doing thumb up gestures to each other while the neighbours stare out their windows in disgust...........F'ing Great.
I haven't had the car on the road yet so am not sure about the new volumn or tone, but from what I've heard already..............it 'will' be worth it.
Worst case.................on a long journey and it gets to much.........We'll just have to look a pair of t*ts and wear ear defenders, but it'll still be worth it.
>> Edited by crazycraig on Tuesday 10th January 12:30
Hi Paul.
As I said, I don't think the removal of the pre cats made any difference, but then again, maybe I'm abit deaf from all the live firing I've done in the past and couldn't notice.
Sleeving, is like I said above. All it is, is you remove the original pipes with the holes in, that were inside the back box which allow the exhaust gases to flow into the back box and deaden the sound, and replace them with solid pipes that are welded inside in their place so in essense making a straight through from the front to the back of the box.
In reality, because most places only cut open the box on 1 side, you can only weld part way round those pipes, I guess thats 1 of the reasons why they repack the back box as you probably still get some gases flowing into the box and if you didn't you'll get this hollow boxy sound. (think that's correct????)
Anyway, the car won't be making it again this weekend, full chassis blitz at the mo, give us a bell and pop round if you want.(no. in back of Sprint)
Speak to you later.
Craig
As I said, I don't think the removal of the pre cats made any difference, but then again, maybe I'm abit deaf from all the live firing I've done in the past and couldn't notice.
Sleeving, is like I said above. All it is, is you remove the original pipes with the holes in, that were inside the back box which allow the exhaust gases to flow into the back box and deaden the sound, and replace them with solid pipes that are welded inside in their place so in essense making a straight through from the front to the back of the box.
In reality, because most places only cut open the box on 1 side, you can only weld part way round those pipes, I guess thats 1 of the reasons why they repack the back box as you probably still get some gases flowing into the box and if you didn't you'll get this hollow boxy sound. (think that's correct????)
Anyway, the car won't be making it again this weekend, full chassis blitz at the mo, give us a bell and pop round if you want.(no. in back of Sprint)
Speak to you later.
Craig
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