E51 The E51 Catalytic Converter Problem

[GregE57]

What a good idea Phil, service exchange maybe.

Good idea!

 

[Seanboardman98]

Hi, the dealer I am purchasing from has said that the cars have been sorted. Is there anyway I can check this and confirm it for myself?

 

[Kenzie (Mary Poppins)]

Hi, the dealer I am purchasing from has said that the cars have been sorted. Is there anyway I can check this and confirm it for myself?

Which dealer have you used

 

[Seanboardman98]

Which dealer have you used

I have used the jpn auto centre near Huddersfield

 

[JohnK]

I would ask them what they mean when they say the cars (assume you mean cats?) have been sorted. What are they saying has been done to sort them?

 

[Seanboardman98]

I would ask them what they mean when they say the cars (assume you mean cats?) have been sorted. What are they saying has been done to sort them?

yes sorry! I meant cats and they said they had been decored

 

[JohnK]

yes sorry! I meant cats and they said they had been decored

Lol! Predictive text gets me all the time
Check out here https://forum.elgrandoc.uk/threads/decatting-an-Elgrand-how-can-i-tell-if-has-been-done.29588/

 

[Seanboardman98]

Lol! Predictive text gets me all the time
Check out here https://forum.elgrandoc.uk/threads/decatting-an-Elgrand-how-can-i-tell-if-has-been-done.29588/

It’s a bugger isn’t it and that’s great thank you!

 

[Silverking]

yes sorry! I meant cats and they said they had been decored

Any mention in their Elgrand ads about de-coring as standard prep on the E51’s they sell ?
I’d ask for evidence the cores have been removed if it’s just say so - a photo maybe or the welds .
If they get funny you asking , I’d have doubts
I had mine de-cored at Tojo soon after buying , dealer was clueless about CATS & I made sure the fog light was fit in the o/s reverse light
Where is your fog light position ?
Hope all checks out for you & you love the new motor

 

[Seanboardman98]

Any mention in their Elgrand ads about de-coring as standard prep on the E51’s they sell ?
I’d ask for evidence the cores have been removed if it’s just say so - a photo maybe or the welds .
If they get funny you asking , I’d have doubts
I had mine de-cored at Tojo soon after buying , dealer was clueless about CATS & I made sure the fog light was fit in the o/s reverse light
Where is your fog light position ?
Hope all checks out for you & you love the new motor

Yeah it says “removed cats” so I’ll check to see if I can see them actually removed and if not then I’ll make sure about the de coring of them. And they have fit the fog light into one of the reverse lights and out a button in just on the right of the steering column

Should have the forms and plates from the dvla this week so hopefully picking it up this weekend!

 

[Dave Lewis]

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.

Hi Karl, a thoroughly good read, answered all my questions in one go, Shame it has to be done was only told by the garage that did the gas conversion after I had the work done, so more expense, thinking I'll go for the decoring option.
Many thanks for your article.
Dave Lewis.

 

[Dave Lewis]

Hi Karl, a thoroughly good read, answered all my questions in one go, Shame it has to be done was only told by the garage that did the gas conversion after I had the work done, so more expense, thinking I'll go for the decoring option.
Many thanks for your article.
Dave Lewis.

Having given this a large dose of thought I would like to remove both cats with replacement pipe work and put the problem to bed once and for all.
Can anyone recommend a reliable supplier of the pipes to do the job , as a retired plumber I feel I can have a go at this myself.
Many thanks in advance.
Dave Lewis.

 

[Bob Edwards]

im getting mine done by a power flow agent near me that will be front cats replaced with 400 cell, rear cats bined (mine are empty) then a y peice into silencer then pipe to back box all for £1250 and lifetime guarantee

 

[Dave Lewis]

Personally I'm looking to remove just the rear cats and replacement piping run to the rear on both as having only just aquired the van, paying to have a lpg conversion done and several other purchases such as a large awning.
Hopefully it will eliminate any future problems.
Dave Lewis.

 

[Bob Edwards]

ah right maybe have a word with your lpg installer

 

[Dave Lewis]

Thanks for the reply, I did Sk the gas conversion installer but he is so busy and has 3 months lead time.. So far the conversion has been a success and as far as I know runs the same as petrol

 

[softin]

Hi! I tried to search, but I couldn't find information about such config: decored front cats and original rear cats - is it pass the MOT or not?
Can anybody prove it?
If it still pass the MOT it seems like safest and easiest config.

 

[JohnK]

Hi! I tried to search, but I couldn't find information about such config: decored front cats and original rear cats - is it pass the MOT or not?
Can anybody prove it?
If it still pass the MOT it seems like safest and easiest config.

Plenty have decored or removed front cats with no resulting impact on mot. Two cats, either front or rear is all that's needed for UK emissions test.
I had my rear cats removed when I first got mine and it's sailed through 3 mots since.
What "proof" do you expect?

 

[BoWise]

So… when the dealer I just paid a deposit to, told me there’s no need to decat or decore if you service regularly… he was talking out of his rear end?

 

[JohnK]

So… when the dealer I just paid a deposit to, told me there’s no need to decat or decore if you service regularly… he was talking out of his rear end?

Unless it's an E50....yes.