E51 Blocked cats nissan elgrand e51

stevemen

Here for life
Premium Member
E51 Owner
#1
For the non believers here a pic an e51 with blocked cats sydrome that we have just bought in.
This cat is totally blocked.Theres a bight torchlight being shone throu the back of the cat with no sign whatsoever of any light getting through, also pieces of the disintergrated front cat are still visable in the rear cat. A pile of cat dust fell out when we removed it.
Add that to the fact that this motor has only done 65,000 miles ( verified) and all recalls had been done in japan including the so called cat fix fuelling ratio adjustment.

Still wanna leave your cats in????
Steve
Tojomotorsuk
Elgrandcarparts.co.uk 20180111_144111.jpg
 

stevemen

Here for life
Premium Member
E51 Owner
#3
Only just got this motor in this afternoon so we havent had full chance to see what extent of damage they may or maynot be. Previous owner tells us it kept cutting out to so hopefully that helped prevent further damage.
First signs are encouraging. No oil coming down the exhaust pipes. No back pressure.
Though there is some issue with cylinder 6 ( bank 2 the bank that usually gets effected first) as when we turned off cylinder 6 revs increase also we suspect the vvt solenoid on bank 2 is malfuctioning.
Came to us with 4 issues on diagnostics since removing rear cats and driving it round the yard to blow all the shit out diagonostics now show no issues at all,and power is now back up to normal, so leads us to believe there is some type of mechanical issue that needs rectifyng.
Hopefully with get time to dig further tomorrow
 

MrRob_in

Part of the furniture (please de-cat your e51/2)
Premium Member
E51 Expert
E51 Owner
#5
Only just got this motor in this afternoon so we havent had full chance to see what extent of damage they may or maynot be. Previous owner tells us it kept cutting out to so hopefully that helped prevent further damage.
First signs are encouraging. No oil coming down the exhaust pipes. No back pressure.
Though there is some issue with cylinder 6 ( bank 2 the bank that usually gets effected first) as when we turned off cylinder 6 revs increase also we suspect the vvt solenoid on bank 2 is malfuctioning.
Came to us with 4 issues on diagnostics since removing rear cats and driving it round the yard to blow all the shit out diagonostics now show no issues at all,and power is now back up to normal, so leads us to believe there is some type of mechanical issue that needs rectifyng.
Hopefully with get time to dig further tomorrow
My first e51 split the front right cat casing apart when it blocked. Sorta save the engine as it soldiered on (burning upto 1/2l per 1k km for 80k miles ... would have been cheaper (at today’s prices) to drop a good engine in it. Seems owner after the one I sold it to didn’t top it up. RIP old girl. 😥
 

SteveMercer

Well-Known Member
Premium Member
E51 Owner
#7
Probblem is people still believe it doesnt need doing regardless of how many times this info is posted here or on crapbook,that and people just buying 1 of a whim because they like the look of it without doing simple research...simple answer is don't do it then make damn sure you have 2 to 3k for a seconds engine because your going to need it.
 

MrRob_in

Part of the furniture (please de-cat your e51/2)
Premium Member
E51 Expert
E51 Owner
#8
There was more than enough evidence for Nissan to issue a recall. That isn’t something car manufacturers do lightly for non safety issues. Shows their acceptance of and the magnitude of the problem. If you think a software fix (only part of the recall) will prevent the problem long term you obviously don’t understand the problem. The point often overlooked is that Nissan’s recommendation is that cats be inspected every 6k miles or annually after the recall. WTF would they say that if they thought it was a permanent fix?
 

stevemen

Here for life
Premium Member
E51 Owner
#10
Update:
No such luck! After giving the engine a good blow out and clearing out all the cat particles the engine is now smoking so it appears thier is damage done to bank 2 , possibly on cylinder 6.
Next week will be doing compression and leak down tests to ascertain the extent of damage before removal and more than likely putting in a replacement engine, not the end of the world but would of been nice to of caught it before it got that far. Mind you looking at how bad that rear n/s cat was the chances were slim.
Steve
Tojomotorsuk
 

nobby62

Here for life
E51 Owner
#14
Yep its on lpg. But doubt very much that this is anything to do with the lpg as the lpg was only fitted a few months back and looking at the state of disintegration of the front cat this issue has accumulated over a long time.

I have read that if the lpg is badly fitted it can cause severe overheating of the cats in which case they would suffer rapidly.. but I’m no expert on lpg.
 

stevemen

Here for life
Premium Member
E51 Owner
#15
I have read that if the lpg is badly fitted it can cause severe overheating of the cats in which case they would suffer rapidly.. but I’m no expert on lpg.
No same here ,but think it would of had to do that super fast to cause this much damage.
I should have all the lpg certicates etc in the next day or two so will know then just how many miles it have done on lpg, have a feeling not a lot and its a prins conversion apparently done by autogas from what im told. We know better soon and let you know.
Steve
Tojomotorsuk
 

nobby62

Here for life
E51 Owner
#16
Interesting stuff.... this is an excerpt from a description of lpg induced valve recession

“Due to the ever increasing cost of LPG and the unsuitability of most modern petrol engines from around 2006 onwards most now suffer from severe exhaust valve and valve seat recession when converted to run on LPG. This is caused by cheap and poor quality materials being used in the manufacture of the exhaust valves and seats, and also the discontinuation of Manually Adjustable Tappets, Self Adjusting Hydraulic Tappets and engines with VVT Variable Valve Timing.

In most modern multi-valve engines in a bid to reduce prices and ease of manufacture, the makers have opted for fixed clearance or solid tappets which cannot be adjusted without extensive work and often the removal of the cylinder head. These components and materials are fine when running on petrol only, I will explain in more detail below.

This is where the problems with valve seat recession starts, LPG once vaporised is a pure vapour and has no lubricating properties at all, this then passes through the inlet valves and into the cylinder where it is ignited by the spark plugs, combustion takes place and the hot spent gasses exit through the exhaust valves.

Because these gasses are very hot and contain no lubricants or additives they very slowly start to burn the valve face and valve seat of the exhaust valve away, this process (called recession) over time eventually causes the valve to recede in to its seat eventually reducing the valve or tappet clearance to zero. Once this has happened it is only a matter of a few miles before the valve head starts to disintegrate causing loss of compression and misfire. This will also lead to catalytic converter failure if the vehicle continues to be driven with misfires by way off unburnt fuel passing through the exhaust system to the catalytic convertor.”

“Subaru, Hondas, Toyotas, Lexus and Nissans can suffer in less than 10,000 miles, even with lubrication systems such as Flashlube fitted these oil injection systems help a little but will not prevent wear entirely.”


May explain the problem with the missfire on one cylinder..
 

Alan Morgan

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Premium Member
E51 Owner
#17
> Hmmm - was that article subject to peer review I wonder?
> I note the bit about lack of lubrication from the vapourised LPG - hence the common use of 'flash lube' type additives.
> If my memory serves me well, (often it doesn't :(), Elgrand LPG users on this forum have not experienced such problems on their vehicles (comments please?) - is that because most Elgrands here in the UK are older than 2006?
> What are Simon's (@Lpgc ) views on this I wonder?
 

Harvo

Here for life
E50 Owner
Premium Member
#19
Does anyone know a garage in North Devon that can decat my E51. I’ve had Chris Wills reply in Wiltshire but he is a fair distance away.
Any decent garage should be able to perform this for you if you explain what needs doing and why. I always use Barry Hews on Pottington Ind Est for MOT and any work I can't get to myself. He knows his stuff and has a good team of mechanics there. I'm sure a chat with him would result in your cats being removed without trouble.