Manifold Assembly Exhaust (LH/RH) DBS 2010

[Scottsanders]

Hi,

Hoping I can get some advice before I make a decision on some works suggested by Aston Martin during the last service. I have had an 'Emissions System Service' warning light on for some time, but when I took it in to get it checked about 10-months ago, AM told me it was a leak in vacuum harness, and therefore wasn't urgent, as may just mean that it fails the emissions checks.

Fast forward to the service, and although no new warning lights have come on, they are now saying that the CATs need to be replaced, as the honeycomb is disintegrating, and this could damage the engine - they showed me a video that they'd taken and there were particles bouncing around in the CATs by the looks of it.

They are suggesting that I replace the LH and RH Manifold Assembly Exhaust at a whopping 4900 GBP each, and whilst I'll of course get the work done if it's necessary, it wouldn't be the first time that AM have suggested replacing something that doesn't need to be replaced in its entirety, so wanted to check:

a) do you need to replace the entire exhaust when replacing the CATs; and
b) would anyone suggest an alternative to AM doing this work? i.e. can this type of work generally be done quite safely by a specialist garage who won't have the AM price tag?

Any advice gratefully received!

Regards,

Scott

[Caslad]

The cats you’re referring to are an integral part of the manifold so if you want to replace with OEM parts the whole manifold needs to be replaced. The front subframe has to be split to allow room to get them out so it’s an expensive job unfortunately. You should get this sorted asap. Catalyst ingestion is a notorious cause of serious engine damage.
The cheapest option would be Bamford Rose’s decat option where they remove the manifolds, open up the cats & remove the honeycomb then weld back together & refit. They will likely offer to replace the rear cats with 200 cell high flow options. They cut & weld a flange on the manifold allowing them to be removed & refitted in 2 parts avoiding the need to muck about with the subframe.
The second option would be aftermarket manifolds, again BR offer their own or you can go with Quicksilver of Velocity AP for example.
As it happens I have some almost new Quicksilver manifolds & cats in the garage which I could do a deal on. PM me if interested.

Edited by Caslad on Thursday 23 March 13:51

[LTP]

Hi Scott,

I can't comment on the DBS other than to encourage you to find out why the cats are disintegrating. If you go for the decat option outlined by Caslad then there would not be an ongoing problem, but if you go for new cats/manifolds without understanding why the originals failed then my limited understanding is that there's no reason why the replacements wouldn't start breaking up as well. One reason given for cat disintegration (and possible ingestion) is misfires, which can be hard to detect on a 12-cylinder engine.

[Scottsanders]

Hi Caslad - thanks for the advice! I'd heard about the decat option, but I'm not based in the UK, so I'd need to find an alternative to Bamford Rose in Dubai who could do this type of work. Same with the Quicksilver manifolds - I'd need to ship them here, so not sure how economical it would end up being. I'll look into it though.

[Scottsanders]

Hi LTP - thanks for the advice too! The reason given by AM is misfires caused by a faulty engine fuse box, so I'll have that fixed first to ensure that the misfiring is also resolved. I might change the coil packs and plugs too.

[Jon39]

Scottsanders said:

... they are now saying that the CATs need to be replaced, as the honeycomb is disintegrating, and this could damage the engine - they showed me a video that they'd taken and there were particles bouncing around in the CATs by the looks of it, ...

There is some irony involved here.

Bamford Rose often suggest that it is wise to remove the V12 manifold cats, because if an unnoticeable misfire begins, unburnt petrol can reach one pair of cats, ignite, then the loose burnt cat particles can be sucked into the engine, result a ruined V12.

Some on here have then posted, never known that to happen, BR are scaremongering to drum up business.

Anyway, leaving that aside, I just wanted to make one suggestion.

As you have described, main dealers routinely replace entire parts, in this case at considerable cost.
When Bamford Rose do a manifold decat, I think they simply cut the cat containers, remove the 'honeycombs', then reweld.
Manifolds are perfectly good, so why replace them.

Perhaps doing it that way would save you a lot of money.
Don't think BR would want you to risk driving your car to them though. Can you arrange transport?

Hope that my thought might become a money saving suggestion. (Worthy of a Trussell Trust donation perhaps?)



EDIT - Sorry I have just seen that you are not UK based, so my suggestion is of no help.

Edited by Jon39 on Thursday 23 March 16:58

[LTP]

Jon39 said:

There is some irony involved here.

I thought the same

[LTP]

Scottsanders said:

Hi LTP - thanks for the advice too! The reason given by AM is misfires caused by a faulty engine fuse box, so I'll have that fixed first to ensure that the misfiring is also resolved. I might change the coil packs and plugs too.

Again, based on what I've read and heard, I wouldn't drive the car at all until the misfire is fixed

[Caslad]

LTP said:

Again, based on what I've read and heard, I wouldn't drive the car at all until the misfire is fixed

Seconded.
There’s quite a bit of valve overlap in these engines which as I understand it is to allow some of the exhaust gases to be returned to the cylinder to be re-combusted to aid emissions. If there are bits of catalyst bouncing about only inches from the exhaust ports they could easily be ingested along with said exhaust gas.

[phumy]

Caslad said:

LTP said:

Again, based on what I've read and heard, I wouldn't drive the car at all until the misfire is fixed

Seconded.
There’s quite a bit of valve overlap in these engines which as I understand it is to allow some of the exhaust gases to be returned to the cylinder to be re-combusted to aid emissions. If there are bits of catalyst bouncing about only inches from the exhaust ports they could easily be ingested along with said exhaust gas.

Its nothing to do with aiding emissions, its all to do at high revs creating a vacuum in the cylinder during its cycle so that when the inlet valve opens it can draw in more air/fuel mixture, its called the scavenging effect.

[Jon39]

phumy said:

Its nothing to do with aiding emissions, its all to do at high revs creating a vacuum in the cylinder during its cycle, so that when the inlet valve opens it can draw in more air/fuel mixture, its called the scavenging effect.

If it is to increase the inlet flow, could it also have a draw in effect through an exhaust port ?

[phumy]

Jon39 said:

phumy said:

Its nothing to do with aiding emissions, its all to do at high revs creating a vacuum in the cylinder during its cycle, so that when the inlet valve opens it can draw in more air/fuel mixture, its called the scavenging effect.

If it is to increase the inlet flow, could it also have a draw in effect through an exhaust port ?

Yes it is a possibility but very small on the exhaust side, the overlap has much more affect to the inlet.

[Jon39]

phumy said:

Jon39 said:

phumy said:

Its nothing to do with aiding emissions, its all to do at high revs creating a vacuum in the cylinder during its cycle, so that when the inlet valve opens it can draw in more air/fuel mixture, its called the scavenging effect.

If it is to increase the inlet flow, could it also have a draw in effect through an exhaust port ?

Yes it is a possibility but very small on the exhaust side, the overlap has much more affect to the inlet.

Thank you phumy.

One particular cylinder (presumably one on each side of the V) seems to be mentioned as the risk.
Think that one is said to have the shortest distance, between exhaust port and manifold cat.

[Caslad]

phumy said:

Caslad said:

LTP said:

Again, based on what I've read and heard, I wouldn't drive the car at all until the misfire is fixed

Seconded.
There’s quite a bit of valve overlap in these engines which as I understand it is to allow some of the exhaust gases to be returned to the cylinder to be re-combusted to aid emissions. If there are bits of catalyst bouncing about only inches from the exhaust ports they could easily be ingested along with said exhaust gas.

Its nothing to do with aiding emissions, its all to do at high revs creating a vacuum in the cylinder during its cycle so that when the inlet valve opens it can draw in more air/fuel mixture, its called the scavenging effect.

Here’s an expert’s opinion.

https://youtu.be/kiCerrUQRGM

[Scottsanders]

Gents, tell me if you think I’m being paranoid here, but I asked for the video that they had taken that demonstrates the honeycomb debris, as it wouldn’t be the first time that AM in Dubai have suggested work that doesn’t need to be done, (very different to the UK!) and the videos look suspicious, mainly because the debris is

a) obviously near the exhaust outlet passed the secondary Cats, and nowhere near the engine, and;
b) seems to be moving towards the outlet very quickly, so unless there is about half a kilo of debris passing through the exhaust on a daily basis, this might be BS!

I can't find a way to share the videos on here, but I think I’m going to ask them to show me the issue in real-time through an automotive endoscope!

[Jon39]

Scottsanders said:

I can't find a way to share the videos on here, ...

The video would be very interesting to view.
I don't think videos can be placed on this forum.
Can you upload it to YouTube ?

Presumably from your description, the engine was running when the video was filmed.
I wonder how/where they fed the endoscope in ?

[Scottsanders]

That was something else that wasn't clear, as they decided to film it without sound :/ They may just have been banging the exhaust from underneath, as on further inspection, it doesn't seem to be a rhythmic movement of the debris

I'll try to upload them, and send a link

[Caslad]

Scottsanders said:

Gents, tell me if you think I’m being paranoid here, but I asked for the video that they had taken that demonstrates the honeycomb debris, as it wouldn’t be the first time that AM in Dubai have suggested work that doesn’t need to be done, (very different to the UK!) and the videos look suspicious, mainly because the debris is

a) obviously near the exhaust outlet passed the secondary Cats, and nowhere near the engine, and;
b) seems to be moving towards the outlet very quickly, so unless there is about half a kilo of debris passing through the exhaust on a daily basis, this might be BS!

I can't find a way to share the videos on here, but I think I’m going to ask them to show me the issue in real-time through an automotive endoscope!

Hi Scott
Forgive me, I’m a bit confused now. I assumed that they had seen damage to the primary cats by looking at them directly with a borescope. (Aston1936 has a YouTube video showing how to do this) but it doesn’t sound like that’s the case.

[Scottsanders]

No, they haven’t shown me any direct evidence of the cat issue!

[Scottsanders]

No, they haven’t shown me any direct evidence of the cat issue!