catalytic converter collapsed

[jill]

I have a 2009 model Nissan murano St (Australian model) with 48000 km on the clock that has had a suspected gearbox issue.
Might I add the murano is the best car I have ever owned.. love it.. and intend to upgrade in a couple of years to the new mode.
The engine is the v6 3.5 litre z51 engine.
Initially the vehicle drove fine.. when it heated up after about 5 hours of highway driving you planted the foot down and the taco sat at about 5500 rpm and free Reved but started surging until you took your foot off the accelorator.
As the vehicle drove longer and heated up more it got worse, after 12 hours of highway driving I could not accelorate over 1500 rpm..
This occurred for the first time after the 40k service and replacement of a fuel sender unit. Initial thoughts was possibly starved for fuel, proven not to be though.
Upon inspection at a Nissan dealer they were able to replicate the issue and have since advised me that the catalytic converters (2 of) have collapsed internally. They are not sure if this is the problem or a consequence of the problem.
The repairs have been confirmed as warranty and parts have been ordered. It was first suspected that an internal seal in the gearbox was the issue and was not maintaining pressure
Has anyone heard of this? Or have any other info on this issue? You guys sound pretty switched on so I thought it was worth signing up and asking the question.
Also if it is listed already in here please link me to the thread..
Thank you

[nitely]

Welcome.

Did you ever experience any coolant smell in your garage or when driving? Did you notice any unusualy oil consumptions at all?

The 09s here in the USA is known to have an engine head gasket problem causing the coolant to leak out of the engines cooling system slowly. http://www.nissanmurano.org/forums/8...kets-09-a.html Coolant intermingling with the engine combustion process and flushed down the exhaust pipe to the catalytic converter will definitely kill the catalytic media and even back flush crumbled catalytic materials back to your engine and damage your cylinders causing major oil consumptions or engine failure--worst case.

This is a probable scenario in your situation. Have your nissan dealer inspect the engine head gasket for signs of leak. This has been reported and posted here by some members. Other factors that can contribute to the destruction of your catalytic converter are poor fuel quality, poor fuel to air ratio--not burning fuel completely, excessive burning of motor oil, etc. But sometimes those cat converter just fail for no obvious reason. pre-cat failure, oil consumption, warranty etc

The high reving and surging you've experience on the highway and final limp mode could be CVT related or throttle sensor related. There are discussions on this as well. RPMS fluctuate at 80 MPH


Atleast its under warranty...Good luck.

[jill]

Thank you for your reply.
No coolant leaks or smells, and no excessive oil consumption either. Only noticed slight increase in fuel consumption losing approx 100km to a tank driving in town.
We saw the photos of the cats today - camera up the exhaust - one of the cats off the manifold had collapsed, the honeycomb was all staggered and broken, actually smashed would be a better word, they suspected that the inside of this one went through to the other cat and ripped its insides up also. No rust or anything like that in there just purely disintegrated the internals and somewhat imploded.
Nissan are replaving both cats at a warranty cost of $5k for the pair. They are hesitant as before they approve they want to know something else didn't cause the failure, but until they get cats in they can not test to see if something else was the cause.
Parts are international, so at least two more weeks without my beautiful car

[nitely]

Did you notice or remember getting any codes prior to failure? SES light.

[jill]

No dash lights at all, temp guage all good. The tech test drovethe car again and popped it into neautral and the car struggled to free rev, the engine did not surge it just struggled to free rev which madehim think of a blockage and put a camera up the exhaust and found the cats collapsed. no codes have been been identified as yet
The car drove fine until it heated up after about 4 hours of driving on the highway. Around town on daily commute never did the issue arise, it only started after the 40000km service, so I questioned the gearbox oil, but was told it doesn't get replaced till like 100,000km service or something like that. I questioned the replacement of the fuel sender unit, as it had been replaced, but the tech was sure it was gear box.
I read your links, but my car didnt have the same symptoms.. never went into a limp mode and only happened when under load
once hot, and putting the foot down to over take a car it would rev till about 5500rpm and then like free rev but go nowhere and would start surging, surging kind of like when a vehicle is starved for fuel, hence the thought of the fuel sender unit maybe a kinked hose or something as it had just been replaced.
as the vehicle got hotter it would start doing it at lower revs, after highway driving for about 12 hours straight I could not get it over 1500rpm. But could slowly increase speed just could not tramp it.
Once the car cooled again drove fine, could tramp the accelorator and would respond as normal.. so it only happens when it heats up after a period of time.