E51 The E51 Catalytic Converter Problem

[Kenzie (Mary Poppins)]

Thank you very much for the advice Steve, greatly appreciated.

So based on that as well as what I’ve seen on the forum I should really take him up on the offer to remove the two rear CATS for £150.

many thanks
Simon

I'd say so could still fail but your chances are better than leaving them all in

 

[SB88]

I'd say so could still fail but your chances are better than leaving them all in

Thank you very much Kenzie

 

[Steve Thompson]

Thank you very much for the advice Steve, greatly appreciated.

So based on that as well as what I’ve seen on the forum I should really take him up on the offer to remove the two rear CATS for £150.

many thanks
Simon

Personally I would go for front cat removal and LPG.

 

[SB88]

As it stands most likely possible option is removing the two rears CATs, has anyone had experience with passing MOTs after removing the two rear CATs or did they fail?

 

[Kenzie (Mary Poppins)]

As it stands most likely possible option is removing the two rears CATs, has anyone had experience with passing MOTs after removing the two rear CATs or did they fail?

From memory most pass the odd 1 fails

 

[SB88]

From memory most pass the odd 1 fails

Many thanks for the advice

 

[Londonglide]

As it stands most likely possible option is removing the two rears CATs, has anyone had experience with passing MOTs after removing the two rear CATs or did they fail?

I had my rear cats removed 10 years ago, and because I knew no better, they cut the flanges off the cats and fitted Stainless pipes in place. Never had a failure due to emissions..still have the flangeless cats in the garage!!!

 

[SB88]

I had my rear cats removed 10 years ago, and because I knew no better, they cut the flanges off the cats and fitted Stainless pipes in place. Never had a failure due to emissions..still have the flangeless cats in the garage!!!

Thank you very much! Does help to give us piece of mind!

 

[Pōru]

As it stands most likely possible option is removing the two rears CATs, has anyone had experience with passing MOTs after removing the two rear CATs or did they fail?

Both rear cat inerds removed and welded backup upon import, never had a problem with emmisions and passed both mots since getting her

 

[SB88]

Thank you everyone for your comments/answers. Rear cats removed and collected yesterday. Looking at the different options available now re Japanese>English for the units, reached out to the companies in New Zealand and Estonia so hopefully sorted soon.

cheers!

 

[Keith Mayoh]

Hi all, new joiner. In the final stages of buying my first Elgrand it is a 2009 E51 Fresh import. Stumbled across this forum last night and found out shockingly about the CAT issue and emailed the dealer last night.

They’ve said the car has all 4 CATs as this issue only affected the earlier models with a factory recall to update the ECU, they’ve offered to remove the rear CATS for £150 extra but don’t think it is necessary as none of their previous customers have had a problem. They’ve also mentioned the extended warranty doesn’t cover exhausts which I assume would also include this.

would appreciate if anyone would be kind enough to offer any advice?
Many thanks

Simon

Hi Simon I am now in this exact same position with my dealer. He too has offered to sort the rear cats out after I found out about the issue on this amazing forum and quizzed him about it. As soon as I asked him he knew of the issue. From what I've read so far on here it's probably better to be safe than sorry so if the dealer doesn't sort them out I am planning to have a mechanic friend remove them and depending on cost I'll either plump for the replacement pipes on eBay or go for a new system. Will prob eventually get the front two checked too.

 

[Reuben]

I’ve mine for 6 years & all 4 cats are in situ. Never had a problem & won’t be removing anything until advised to do so by my qualified mechanic. I got my Elgrand from the main Scottish distributor of Elgrands, at the time anyway, & they hadn’t had any warranty issues with cats failing, engines exploding etc. I don’t doubt that some vehicles have problems regarding this issue but not every Elgrand.
I’ll put my tin hat on now & wait for the inevitable barrage………

 

[Kenzie (Mary Poppins)]

I’ve mine for 6 years & all 4 cats are in situ. Never had a problem & won’t be removing anything until advised to do so by my qualified mechanic. I got my Elgrand from the main Scottish distributor of Elgrands, at the time anyway, & they hadn’t had any warranty issues with cats failing, engines exploding etc. I don’t doubt that some vehicles have problems regarding this issue but not every Elgrand.
I’ll put my tin hat on now & wait for the inevitable barrage………

Which qualification would you like and il clumb in loft to dig them out well regarded issue on all cars mot just elgrands expected life in nominal use is 10 years

 

[Reuben]

Which qualification would you like and il clumb in loft to dig them out well regarded issue on all cars mot just elgrands expected life in nominal use is 10 years

No need to trouble yourself on my account but thanks for offering.

 

[JohnK]

Your car, your choice. Its certainly not the law to decat.
But, bearing in mind dealer warranties normally last 3 - 6 months, I'm not surprised the dealer hadn't experienced any warranty issues due to cats.
All cats will fail in time and with the Elgrand quad system, there is an inevitable outcome that the rears will block when (not if) the fronts break down. Its just a matter of time. The choice for me was spending a little as a sort of insurance or keeping my fingers crossed that they didn't give up the ghost while I still owned the van. Easy decision on my part

 

[Kermit]

Fiiiight


We were lucky, the fronts were done in Japan.

 

[Zenith]

Does removing the rear cats increase exhaust noise?

 

[Londonglide]

Does removing the rear cats increase exhaust noise?

Almost certainly not, and even if it did, you would probably need a before and after decibel meter to confirm it

 

[GregE57]

THIS IS NOT FORUM LORE. THIS IS NOT A MYTH. THERE HAVE BEEN MANY DOCUMENTED INCIDENTS WHERE OWNERS HAVE HAD THEIR ENGINE BLOW UP BECAUSE OF THIS ISSUE. YOU HAVE BEEN WARNED.

CHECK OUT THIS THREAD FOR PROOF

LIST OF AFFECTED MEMBERS

The problem

A widely known issue with the Nissan Elgrand E51 is that the rear cats get blocked causing catastrophic
damage to the engine.

The problem starts with the fact that the E51 has a QUAD CAT SYSTEM. This means there is a PRIMARY and a SECONDARY catalytic converter on EACH BANK of the V6 engine.

The PRIMARY cats are the ROOT CAUSE of problem. Through use, after heating up and cooling down, they start to deteriorate. This happens with ANY ceramic catalytic converter when they reach the end of the their life. As the PRIMARY cats starts to break down and fall apart, the debris is pushed back through the exhaust. At this point, they come into contact with the SECONDARY cats, which creates a blockage.

As more and more of the PRIMARY falls apart, the blockage will prevent any exhaust gasses getting out. The exhaust gases (and dust particles) then build up pressure and go to the only place they can, back into the engine. It doesn't take a mechanic to know that if you put exhaust gas mixed with catalytic converter debris back into an engine, it's not going to last long.

So, that covers the problem, what can you do about it?

There are 3 main options.

1/ DECORE the SECONDARY CATS. This is a simple process. You remove the secondary cats, cut an opening in the top, smash the internals out, weld the opening shut again and re-fit them. This removes the point at which the debris from the PRIMARY cats will get stuck creating a blockage. The debris is just pushed out the back of the exhaust. THIS IS NOT A 100% SAFE OPTION. Debris can still trap itself within the primary cat or the mid box of the exhaust. Although removing the rear cars reduces the chances of catastrophic failure exponentially... it will not 100% stop it from happening.

2/ Remove the SECONDARY CATS. Same principle as option 1, but you remove the cats altogether and replace with a straight through pipe. This is more costly than option 1, BUT what it means is that when it comes to MOT time, you still have the cats to fit to the vehicle if there are ever any issues. As with option 1, this is not a 100% failsafe option for the same reason outlined above.

3/ By far the most expensive option, but still an availability if you have the funds to allow it. Replace the WHOLE system (Manifold back) with a custom made stainless exhaust with single stage, high flow metal sports cat. Dig deep for this one, but the noise will be worth it - This option will 100% remove the risk of damage caused by the standard catalytic converter failure problem.

REGARDLESS OF WHAT METHOD YOU CHOOSE - YOU MUST CHECK FOR DEBRIS FROM FAILING FRONT CATS AND INSPECT THEM BEFORE YOU MOVE FORWARD. IF THEY HAVE ALREADY STARTED TO DETERIORATE, YOU SHOULD HAVE THE WHOLE SYSTEM REPLACED AND THE ENGINE HEALTH CHECKED BY A PROFESSIONAL.​

But what about.......?

You will fail an MOT if you remove the rear cats and the tester knows they should be there. So if you do fit straight through pipes, keep the cats and then you can fit them again at a later date if you need to.
If you go for option 1, make sure the access hole is cut in the top of the cat so that the head shield will cover the weld when it's sealed up again. If the hole is on the bottom, and the tester can see that they have been tampered with, he'll fail it.

Emissions are NOT affected by removal of the secondary cats. They are only part of the system due to the strict "cold starting" emissions policies in Japan. In the UK the emissions test is done on a warm engine, and therefore the secondary cats serve ZERO purpose.

Is this legal?

I don't know what PC Plod can do about you removing/modifying the cats. But, if you tell an MOT tester that you have modified the cats in any way, and it fails, then technically the car is not road worthy. We know this is bollocks. It'll still pass the emissions test, it will still drive perfectly OK, and you have removed the risk of having your engine blow up when belting down the motorway at no more than 70 (of course).

The choice on what you do is up to you. Keep them if you want. But then every time you drive your E51 you will be wondering when the engine is going to blow up. I know from a personal point of view, I'd rather take the risk with the MOT tester than have catastrophic engine failure and a £4500 engine rebuild bill.

I heard about a Recall for this problem!?

The recall has NOTHING to do with this problem. All it will do is prolong the inevitable. The recall was put out to adjust the fuelling. If your car is subject to the recall, the engine map was putting too much fuel into the engine. This meant that excess fuel was getting blown out of the engine following combustion and then igniting in the exhaust system due to the heat. This meant that the exhaust was getting a lot hotter than it should causing premature deterioration of the primary cats.
With the recall in place, the engine will not overfuel... but it does not mean that the primary cats will not start to disintegrate over time.

There have been at least 2 instances that I know of where a car that was NOT on the recall list has had the engine fail because of blocked cats.

Why does this need doing?

Cars built for EU and UK roads are designed with the climate in mind. Therefore, as part of the manufacture process, there are treatments applied to the bare metal to prevent the chassis corroding. JDM cars are NOT done, because the climate in Japan is very different to ours.

The underseal is required to ensure that your car doesn't turn into a pile of rust over the winter. More importantly, because you are doing this AFTERMARKET, it is something that is seen as temporary, not permanent. The products applied will, over time, wear off or get damaged thus leaving untreated metal to come into contact with salt and moisture.

The better the product you use, the longer it's life. There may even be products out there that come with a "life of the car guarantee"... but I'm sure they'll cost more than £400!

With that in mind, discuss the options available with the garage you chose for your underseal and discuss repeat applications and how often they will be required. If they want your continued business, they will offer all options and tailor the service to your requirements and budget.

Thanks for the information!

 

[GregE57]

No, because no one in there right mind drives or admits to driving one long enough without removing the rear cores to worry about mpg with them in.

Honestly in same conditions you can drive the same route and get 18 to 28 mpg depending on your right foot, how the heck anyone can say doing X saved 2 mpg without removing all the other variables is beyond my comprehension.

That’s a shame, I put £100 in the tank yesterday!!