E51 E51 Cats (Newbie panics...)

Charisma

Newbie
E51 Owner
#1
Apologies in advance as I know there is an extensive background under the need to know thread, which I have reviewed.

But I have a few questions that I appreciate the vast experience within this group in keeping me right. Regarding the:

* "average" life span of the Cats with general wear and tear?
* Reliability of the Cats for the E51?
* How much do they cost to replace, etc?

I am just about to take receipt of my E51 this Saturday with a mileage of c 45,000 miles, MOT passed two weeks ago etc.

All of the detail posted in the previous threads has been incredibly helpful. But I must admit it is leaving me in a cold sweat and I would welcome any guidance to ask the dealer on the day to help calm my initial fears and allow me to enjoy the van without a pending sense of doom!!

Thanks in advance and all the best.
 

spuddyo

Well-Known Member
Premium Member
E51 Owner
#2
I removed the rear CATs from my 2009 E51 when it had 76,000kms on it, Cats were like new, no signs of blockage or damage. Better safe than sorry even though it's only a relatively small number that reportedly get clogged. Just remove them to minimise risk.
 

Baz L

Well-Known Member
Premium Member
E51 Owner
#3
Mine's an 03 which had 45000m on the clock. Drove mine for a year before I removed them and were spotless but as said above get them removed for peace of mind. Do you have any recalled paperwork which may of been done in Japan?
 

Karl

Founder
Staff member
E50 Owner
Premium Member
E50 Expert
#4
Average lifespan - you can't put this in years or miles. It's to do with the amount of times they have heated up and cooled down. Unless you know how many times the engine has ran long enough to get them hot, you won't know. A high mileage car might have heated and cooled less often because of long trips. A low mileage car might have done lot's of little trips, and therefore the cats have been put under more pressure. Also depends on how it's been driven etc. So you cannot put a figure on this.

Reliability of cats - same as any other car. But MOST of them don't have a quad cat set up. This issues is not limited to just the Elgrand E51/52. It's the same with any car that has a pre and a secondary cat, where the second cat has a mesh to prevent bits getting through. If the secondary cat has an opening for debris to fall through, then the risk of blockage is limited.

How much to replace - cats are usually expensive. I don't know anyone who has bothered replacing them. By removing the secondary cats, you allow the primary cats to fall apart and blow out the back, but this means that at some point you will be left with no cat. This will throw an EML light as the sensors will not pick up a change pre and post cat. I would think at this point most people replace with second hand parts, but I don't know much about this as I don't own a 51 and there hasn't been much discussion on replacing the primary cats once they have shit themselves out the back.

Just get the secondary cats decored for now. They are not needed for UK MOT and will put your mind at ease.
 

Alan Morgan

Here for life
Premium Member
E51 Owner
#7
@Charisma Get the rear cats de-cored. Costs should be 2hrs labour.

On your soon to be vehicle, check the tyres. Jap tyres need replacing soonest.

Plenty of posts on decoring and jap tyres
 

feeney33

Member
E51 Owner
#8
Is this a job that your average exhaust centre would be able to do , or even willing to do.
Or is it a job for a specialist, maybe elgrand expert like BMR.
 

SQUIZ

Member
Premium Member
E51 Owner
#9
Any half decent local garage should be able to discretely de-core both your rear cats.There's nothing specialist involved.It should take them no more than two hours (if they are slow) and cost almost zero in materials (maybe a bit of welding wire and an odd nut and bolt)
 

nobby62

Well-Known Member
E51 Owner
#12
Dont panic, the cats wont block as soon as the car reaches our shores.....just plan to remove or decore them as soon as you can get round to it purely for peace of mind due to the fear of the posibility of failure. But as most above have commented the cats are perfect when eventually removed. I will be having a stainless system fitted to mine in a few weeks for peace of mind and to improve looks / exhaust note etc but i expect the cats to be ok and i will report on here once i get a look at them. I have owned mine a year now and taken her from 25 to 34k miles in that time without any issue... I have a theory that most cat failures are probably high milage cars that have been brought over here, lpg'd and driven hard but its just a theory as there appears to be no statistics on milage or anything else, just horror stories. I'll probably get shot down in a few minutes but as i say its just a theory and i hope I haven't just cursed myself
 

Lpgc

Well-Known Member
Premium Member
#13
I de-cored cats from a customer's E51 about 5 hours ago, this 07 plate only had around 57kkm, I've decored cats on several Elgrands with various mileages, haven't seen hint of a problem yet.
But this forum holds testament that problems do occur...
I wonder if cat problems have been caused by other issues that the owner hasn't been aware of. A failed O2 sensor could cause rich running that could cause premature cat failure.

Usually if cats fail (block) it is very apparent to a driver who is used to driving the vehicle because engine power will be down.

Simon
 

Lpgc

Well-Known Member
Premium Member
#14
I missed the bit in Nobby's post above that mentioned LPG conversion in the same sentence as cat failures... I'll just get this bit in - A properly installed and setup LPG system won't cause cat failure ;-)

Ways that cats can be damaged include if the engine burns oil (oil contamination), if there's been a head gasket failure (antifreeze poisons cats), very rich fuel mixture (regardless of which fuel the engine is running on) causes cats to overheat and fail. If an engine sensor is broken this can indirectly lead to the engine getting a mixture that is too rich (again regardless of petrol / LPG). If the LPG system isn't installed or setup/calibrated properly this can lead to the engine getting too rich (or too lean) mixture. Too rich is bad for the cats (regardless of which fuel), too lean is bad for the engine (regard;ess pf which fuel). An LPG system could only be the cause of cat failure if the installer didn't do their job properly, if an LPG system works as it should the cats and the rest of the exhaust system and the engine itself
will all last longer than if the vehicle was run on petrol.

Simon
 

Karl

Founder
Staff member
E50 Owner
Premium Member
E50 Expert
#15
But this forum holds testament that problems do occur...
I know personally of approx. a dozen either fatal or near fatal events since I got my Elgrand just under four years ago.

I also know of a fair few more people who have de-cored and found debris starting to build up.

It's not common for them to go... but the risk is there, and for the sake of £100 to get them de-cored, it's not worth risking blowing your engine.
 

Lpgc

Well-Known Member
Premium Member
#16
I know personally of approx. a dozen either fatal or near fatal events since I got my Elgrand just under four years ago.

I also know of a fair few more people who have de-cored and found debris starting to build up.

It's not common for them to go... but the risk is there, and for the sake of £100 to get them de-cored, it's not worth risking blowing your engine.
I charge £100 to decore rear cats on Elgrands too, so if I was an outright money grabber I wouldn't be saying this lol...

What's the meaning of the word 'fatal' here? What I mean is, the car won't blow up and kill you if it has a blocked cat, worst case scenario is that the exhaust gas cannot escape so the exhaust system North of the blocked cat gets pressurised to a level higher than normal and the engine works harder and harder (as blockage becomes more pronounced) to pump it's own fumes until we reach a point where the engine won't run anything like properly because the back pressure is too high... but the engine's cylinder pressures reached with this back pressure could never exceed the pressure they reach in normal operation when you put your foot down - Blocked cats don't normally lead to engine damage, they usually lead to much reduced performance. Cat problems will in some cases be a symptom of other underlying problems rather than the initial cause of a problem, such underlying problems may be more likely to go unnoticed on a Jap import than on a Euro vehicle because a lot of garages won't have facility to make use of Jap vehicles built-in on-board diagnostics and the engine warning light seems less likely to light-up when the mixture hangs rich. I've advised a couple of Elgrand repairs customers about mixture problems where the underlying cause seemed to be lambda probe issues, such problems/issues would normally turn on the MIL light on a Euro car but didn't on their vehicle, just the type of problem that would likely eventually lead to broken cats.

Incidentally mate I intend to become a paid up member of this forum, not because of the Photobucket situation, I should help support it given that it's been the source of a fair bit of business for me, fair's fair etc.. :)

Simon
 

Phil

Here for life
Premium Member
E51 Owner
#17
Sounds pretty straight forward to me. If you've spent thousands buying an Elgrand & then £1600 to have Lpg system fitted - why wouldn't you spend an extra £100 to insure against the small risk of the cat problem occurring? No brainer & peace of mind :)
 

Lpgc

Well-Known Member
Premium Member
#18
No argument Phil, I'd probably decore the rear cats if I owned an E51 too, but I'd be doing it for a different reason... Cats restrict exhaust flow a bit, which causes the engine to work a bit harder just to expel it's own fumes, so decoring cats generally helps efficiency (economy and power) a tiny bit. I wouldn't have much concern about cats getting blocked and damaging my engine because I ensure my engines are running properly (correct mixture etc), which isn't necessarily the same as just seeming to drive properly. A rich mixture on any vehicle is likely to lead to premature cat failure and I've seen a few Elgrands where the engine was running rich due to other un-diagnosed problems such as a failed lambda probe. If I was a layman I'm not sure whether my first £100 put towards looking after an E51 would go on a decore or on paying for decent diagnostics to ensure there were no other underlying problems such as failing lambda probes... Thinking goes that if a rich mixture can cause failed cats and also causes reduced economy and fuel wash of engine cylinder bores it would be better to cure rich mixture (with it's multiple but often undetected symptoms) than to pre-empt the potential knock on effect of such problem (eventual damaged/blocked cats) by decoring the cats. It seems a lot of garages and the MOT test don't always pick up on such problems because I have seen glaringly obvious problems on vehicles that have just had diagnostics done or just passed an MOT where the owner was told the vehicle had no problems whatsoever... so by decent diagnostics I mean by someone who knows what they are doing and who won't just say everything is OK on the basis of a normal MOT type emissions test or absence of engine warning light illumination. An LPG conversion provides a very good window to pick up on such problems and whenever I convert a vehicle to LPG or even do minor work on an LPG system I pick up on such problems by default but I am able to detect issues even on petrol only models by means of reading OBD data (even on Jap imports) and/or temporarily connecting a few wires from an LPG ECU to engine bay wiring (to get that window).

Simon