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Discussion Starter #1
This past week my engine hasn't been purring so quietly so I got it over to the dealer to have them check it out - turns out the engine inhailed some of the stuffing from the catalytic converter. This in turn is causing sticky valves and main bearing noise. The dealer told me this is a catastrophic condition in which replacement of the engine is the only path to fix it.

I asked if this happens often, they told me no - but it does happen. So I'm looking around for used engines - all the gaskets and required attachment hardware is $1900, the dealer wants $2400 to stuff any engine in and the used engines out there are between $1300-$3500. Looks like a nice 6-7K hit to the wallet.

BTW the engine has 135,000 highway miles and has been great up to now.

Time to go drink....

WG
 

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WG-

Are you serious?!? The dealer claimed your engine inhaled the stuffing from the cats?!? That is total BULLSH*T!!!!

The catalytic converters are downstream of the engine. How could the internal honeycomb structure possibly flow upstream against the exhaust flow and enter the engine? What do they think, that you have salmon in the catalytic converter?!?

Who is this dealer? I would contact NNA ASAP and relay this story to them.

-njjoe
 

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What Joe said... That's a physical impossibility!


Dan
 

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I think it was the dealer who inhaled something...

I have never ever heard such a BS....I have to say though dealers imagination to create BS has no limit....

As Joe said - call NNA. They need to know things like this.
 

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WG-

It infuriates me that the dealer would make such a blatantly erroneous claim. He most definitely needs to be reported.

Here's the info for Nissan Consumer Affairs.

Nissan Consumer Affairs
P.O. Box 685003
Franklin TN 37068-5003
(800) NISSAN-1 (or 800-647-7261)
8:00 a.m. - 5:00 p.m.,
Eastern / Central Time / Pacific Time
Monday through Friday

-njjoe
 

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Discussion Starter #6
Thanks guys - I'll call Nissan and report this dealer.

The dealer is Bill Kay Nissan in Downers Grove, IL

I'm going to get a 2nd opinion from another dealer.

I agree that entry via the exhaust system seems impossible. I know how an engine works, I've rebuilt 2 in the past. Even with engine braking with downshifting, air still flows out the exhaust ports. The cats are located very close to the exhaust header, but for the life of me I can't imagine a reverse flow pattern.
 

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Whoa!
Don't go off half coked.

Backflow is entirely possible. In fact it is not that unusual due to overlapping pulses of the valves.

And........ if the Cat's mat was shredding, it could be sucked back into the engine. That would be rare,but certainly not impossible at all.


Here's a good explanation of how backflow occurs.
It only takes a bit of imagination to see how a shredded cat mat could be sucked into the engine.


http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=47




Homer
 

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Homer-

Good article. I enjoyed reading it. I also enjoyed the author's disdain for "tuners".

I agree that under certain conditions it is possible for gas backflow to occur. However, in order for the VQ to ingest the cat's honeycomb, the volume of the backflow would have to exceed the volume of the gas at the head of the cat and in the exhaust manifold. The backflow is just not that great.

In addition, how does the dealer justify his claim that the inhaled stuffing is responsible for the main bearing noise?

A call to Nissan is warranted.

-njjoe
 

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If the dealer did not show you damage to the spark plugs, then pull them and look carefully at the tips. If something got into the cylinders, you can usually see evidence of damage on the plugs.

Unfortunately, I am an extreme newbie to Nissan and do not know if the engine is a non-interference engine, or not. If it is an interfence engine, then it could be possible for some particles to get between the valve and the seat, and hold the valve open for the piston to hit it.

Even considering that, it still seems highly unlikely to me for the engine to eat the cat's guts.
 

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Sigh.


It is a known Nissan problem having to do with their crappy cats and pre cats.
Valve overlap (BOTH open at the same time) is common in engines with sporty cams.


I'm not going to argue.


But you are so wrong about backflow not being able to get into the engine because of positive pressure at the cat...........

Lets suppose the Cat was disintegrating....
Now what would be the probable symptom here?
Its quite possible there would be increased back pressure due to the cat being partially blocked.
In other word there would be a tendency for the pulses of exhaust gasses to be pushed back into the engine.
That's called back flow.




Take a look at the Altima forum. They have had Catalytic problems.......


http://www.nissanclub.com/forums/2002-2006-nissan-altima-discussion-2-5-3-5/185326-excessive-oil-consumption-2002-altima-se.html


Now, to be clear, I am not saying that this is Wrench's problem. After all, Nissan is saying it.

What I am saying is that this is entirely possible.
It has happened to other engines and could happen to you if your cat starts shredding.

IMO I would find out if the cat was under warranty.
They have far longer warranties than engines.I believe it is covered by US Govt regs.

Then, if an "in warranty Nissan cat" caused my engine failure, I would demand the engine be replaced free of charge too.

Homer
 

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Yeah, I imagine you are right. 135K is a lot. I know the Cat is covered for a lotta miles, but probably not that many.
Oh well, it was just a thought.

It is still possible that a bad cat can block the exhaust, cause negative pressure at the exhaust manifold and cause pieces parts to be pushed back into the engine through the open valves.

Homer
 

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hfelknor said:
Sigh.


It is a known Nissan problem having to do with their crappy cats and pre cats.
Valve overlap (BOTH open at the same time) is common in engines with sporty cams.


I'm not going to argue.


But you are so wrong about backflow not being able to get into the engine because of positive pressure at the cat...........

Lets suppose the Cat was disintegrating....
Now what would be the probable symptom here?
Its quite possible there would be increased back pressure due to the cat being partially blocked.
In other word there would be a tendency for the pulses of exhaust gasses to be pushed back into the engine.
That's called back flow.




Take a look at the Altima forum. They have had Catalytic problems.......


http://www.nissanclub.com/forums/2002-2006-nissan-altima-discussion-2-5-3-5/185326-excessive-oil-consumption-2002-altima-se.html


Now, to be clear, I am not saying that this is Wrench's problem. After all, Nissan is saying it.

What I am saying is that this is entirely possible.
It has happened to other engines and could happen to you if your cat starts shredding.

IMO I would find out if the cat was under warranty.
They have far longer warranties than engines.I believe it is covered by US Govt regs.

Then, if an "in warranty Nissan cat" caused my engine failure, I would demand the engine be replaced free of charge too.

Homer
BINGO. I was about to post the Altima precat issue but Homer was way ahead of me. It is possible for components DOWNSTREAM of the engine to damage an upstream component!
 

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The cats are warranted for 8 years or 80,000 miles. It doesn't help WrenchGremlin, but it is good to know.

-njjoe
 

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Will it ever stop

One damn thing after another. At least it should all be paid for by Nissan.!
 

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Discussion Starter #16
Just wanted to take the time to follow up with what happened with the engine.

After getting over the emotional hit of the dealer telling me my engine was terminally ill and researching the used engine market, I decided to trouble shoot my engine instead. Besides, now the engine has an exhaust leak because the dealer didn’t replace the gaskets when they took it apart… and they missed a bolt that secured a line to the intake plenum, nice attention to detail Nissan.

My engine rattles on falling revs, like a bad pulley tensioner and the engine also hesitates and is going from 0-60 in about 15 seconds – way off the mark. But there is no oil smoke on startup so perhaps there is hope.

I ordered a new pulley tensioner and bracket and put it on, but there was little to no improvement with the rattle, perhaps the dealer was correct in saying that catalytic material made its way into the main bearing.

I went out and purchased an ODB2 reader and pulled some codes that were logged. The first was P0327. This indicated low-voltage on a knock sensor. I traced it down to a short in the knock sensor sub-harness - $105 for a replacement and more for gaskets. While I had the intake manifold off I pulled all the plugs and did a compression test too. Standard compression is 185 psi with an allowed variance between all cylinders limited to 14psi My engine with 138,000+ miles ranged from 192-200 psi, basically its hardly broken in. All the valves are seating properly and certainly the rings and cylinders are in great shape, hmmm… then how did any material make it to the main bearings???
Got the engine back together and wow… most of the HP is back, running 0-60 in about 8.5 seconds, but that death rattle is still there.

I had one more code – P420 catalytic converter on bank 1 is end of life. I purchased an aftermarket catalytic converter made by Eastern for $270, a far better deal than $550 ($750 MSRP) for OEM. It took several hours to remove and install the new catalytic converter; turns out the eastern converter didn’t tap 2 of the holes that receive the posts from the OEM converter. A 10mm 1.5 standard thread tap did the trick. The bottom bracket is different from OEM too; its holes are through bolt instead of threaded. Another trip to the store to get nuts and bolts for the mating resolved that issue. When I removed the OEM cat, the insides were lose and rattling around, but it looked intact. Once everything was put back together the death rattle had gone away, along with the exhaust leak created by Nissan Neanderthals. Performance improved a few ticks, to 7.8 seconds. The MO is cured and it didn’t cost me $12000 dollars to replace the engine after all. From now on I do all my own wrenching, its sad when you can’t bring your car to a certified 5 star dealer to get honest work performed. I would have gladly paid them to replace the cat and fix the wiring, but they were either to green to make the proper diagnosis or perhaps seen an opportunity for green, which I really hope isn’t the case.

The catalyic converter died because the gap on a spark plug was to far to jump and raw fuel was burning up the convereter. I would strongly recommend NOT waiting until 105K miles to change the plugs. Probably 80K miles provides enough of a safty margin should a plug be wearing quickly. It sure beats spending $1000 at the dealer to replace the catalytic converter.

Once again a happy MO owner.

WG
 

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Being persistent pays off! :p

Regular maintenance states that I should change my MO's spark plugs every 100,000 km (60,000 miles).

I don't know what it is for the US version but if it is also 60,000 miles, then the reason for the failure is a lack of maintenance, which would mean that Nissan Corp. is not responsible at all and that this is not a design flaw.

The dealer relies on the mechanic's diagnostic so it often happens that one incompetent worker makes the entire company looks bad. The opposite is also true. A service company is only as good as the people it employs.
 

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Discussion Starter #18
The US maintenance is 100,000 miles, the plugs are rated for 105,000. It was doing a lot of long distance travel and within 1 month had over shot the service cycle by 7K miles. My fault for not having them changed earlier. I had asked the dealer to do it at 85K, when it was in for warranty work, but when I picked up the car they told me the plugs didn't need changing until 105K.

I understand that companies employ people of all skills and some are gifted while others are challenged. When the service manager is going to tell a customer that a repair bill is over $12,000 they should be sure the information is correct. I also asked them to fix the sticking door handle on the rear hatch. They told me I needed a new cable in addition to the handle because the current one is stretched out, but since the engine was shot they didn’t do a thing. I replace the handle on my own and the existing cable works just fine. This isn’t the first time I’ve had questionable service from this dealer.

One of my co-workers has a 2003 maxima with the same engine as the MO and its also high mileage car. He has a slight oil leak on the valve cover, the other Nissan dealer that I have to choose from told him that oil is getting inside the plugs and fouling them out and that the plugs should be changed. The also told him he needed a new oil pump because they found a drip of oil on that too. Both repairs are just seals. Of course they never figured out why his car is knocking. Telling him that the oil leaking is causing the plugs to foul out is an amazing connection. I really wish the service departments would stop making crap up.

I do believe that there are GOOD Nissan service shops around Chicago; I just need to find one.
 

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WrenchGremlin-

Nice job and excellent write-up!!

As I had stated in earlier posts, I had my doubts that your engine had ingested the cats. It was even harder to believe that the cats had damaged the mains.

The dealer really blew the diagnosis on this one. They should have been more thorough with their troubleshooting, especially with such a big-ticket item like this.

Regardless of the mis-diagnosis, what is not acceptable is how they put you car back together. They should have known the exhaust gaskets were missing when they started the car, and replaced them before you picked up the car. There is no excuse for that.

I am glad you were able to repair your MO without having to fork over twelve-grand. You must be feeling good about now. :4:

-njjoe
 

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WrenchGremlin, excellent call on the compression test. I'm not sure how the dealership came up with you needing an engine replacement WITHOUT doing a compression test, seems there should be no excuse for a trained service technician.

I would do one last thing to make sure your engine is healthy. On the next oil change, take an oil sample and send it to a lab for analysis. They can look for excess bearing material in your used oil.

BLACKSTONE LABS is one place, but there are others.
 
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