# '03 2.5 Pre-cat failure



## SheckyW (Nov 13, 2008)

Has anyone seen a pre-cat failure on the 2.5 that DIDN'T cause major engine damage? Reason I ask:

Our '03 Altima would not start all of a sudden one morning. We took it to the dealer (since they had just replaced a cam sensor a few weeks before, and it was acting just the same). In the process of diagnosing it, they broke off the upper O2 sensor and noticed that the screen was damaged or partially missing (I haven't looked at it myself yet), so they recommended a new engine at about $4500 (HA!) OK. 

Problem is, from what I have read, most of the time what happens is that foriegn material enters the cylinders through the exhaust manifold, scoring causes severe oil consumption, the bearings are starved for oil and the engine seizes. This engine has had no recent history of oil consumption (in fact I had just checked the oil level a couple of days before - right on the full mark), no performance issues, overheating, etc. etc. The dealer claims it will run now (they think the exhaust was clogged) but I haven't tried to start it yet.

I figure since the car is worthless and I have nothing to lose, I am going to pull the head and check the condition of the cylinder walls, pull the pan and maybe pull a main to check the condition of the bearings. If I get to that point and all looks ok, I'll hog out the pre-cat and slap it back together. If not, I'm sure I can put a motor in it for way less than $4500.

Anyhow, just wondering if anyone else has had a similar experience.

Thanks

Shecky


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## fivetears (Jul 26, 2007)

Were you burning oil? If not, replace the precat and move on. Intermitant starting problems could be BOTH crank & cam sensors; same P/N; $44 each. Sould always be replaced at the same time. Huge problem with 2003 QR25DE's and Nissan.


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## SheckyW (Nov 13, 2008)

Yeah as it turns out, I tore the motor down and there's no evidence of any damage, just normal wear from 130,000 miles, as I suspected. Just going to freshen it up, new rings and a gasket kit, and I'm thinking about getting one of the aftermarket headers rather than fool with the precat. Cheaper anyway, I believe.


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## fivetears (Jul 26, 2007)

Actually... no; not cheaper. Hindsight being 20/20 the sub-$400 cost of a new precat is much cheaper than the cost of the "Header Novelty" wearing off. I converted mine back after the interior resonation became a nuisance. Change your precat and be done with it. But if you must...
http://www.nissanforums.com/l31-2002-2006/137384-stock-qr25de-altima-megan-racing-header.html


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## SheckyW (Nov 13, 2008)

I guess I was going under 2 mistaken assumptions: I had heard that the noise level increase wasn't really noticeable, and the factory pre-cat / manifold was more expensive. What about the possibility of the degradation of the new pre-cat? I'm planning to sell the car once I get it back together and put a few miles on it, but I don't want somebody else to have an issue with it down the road...


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## fivetears (Jul 26, 2007)

Noise level is a subjective concern driven by buyer preference. Spend the money on the new precat if you're genuinely concerned about a buyer. There won't be another "issue" with it for another 80K miles. Pass the repair cost off to the buyer. Business is business.


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## Hahn25 (Apr 18, 2009)

Just took my 03 Altima 2.5S to the Nissan Dealership that I bought it from. They REFUSED to do a visual inspection of the precat. Downright said "no" 'cause the computer wasn't throwing a code for the precat. Who ever heard of a dealership mechanic turning down money as not to look at a part that they insist is fine? The car has 72k so it still falls under the Federal Emissions Warranty (http://www.epa.gov/oms/consumer/warr95fs.txt). It burns 3 quarts of oil every 400 miles, it runs really rough, cylinder 1 is misfiring, and now they say the head gasket is blown, but they will not look at the precat because the ECU hasn't reported a problem... So, even if your car looks like it is on fire, but the ECU says "no" ... it's not /really/ on fire, it would just appear that way. x.x

Calling up Nissan Consumer Affairs on Monday morning and getting the car checked out by a "qualified" mechanic so that they can write up a report, so that I can take it back to Nissan with a verified pre-cat problem. 

Anyone ever dealt with Nissan refusing to visually inspect their pre-cat? According to Nissan Recall ID# 5450, it requires Nissan to test and look at the pre-cat, and if there is ANY damage to the pre-cat, they must replace the engine.

Anyone ever get Nissan to replace an engine before the 80k mark under the recall and federal warranty? If so... what's the secret?

Thanks. Really frustrated.


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## Nickaltima (Jan 11, 2008)

heres a tip for all 2.5 alty owners..avoid all this pre-cat bullshit and just put an aftermarket header on your car that rids the pre-cat...wayyyy cheaper and you avoid all the stresssssss and youll gain a lil power as well


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## bcgonzal15 (Mar 4, 2011)

*Nissan Altima 2.5 giving me hell 144k*



Nickaltima said:


> heres a tip for all 2.5 alty owners..avoid all this pre-cat bullshit and just put an aftermarket header on your car that rids the pre-cat...wayyyy cheaper and you avoid all the stresssssss and youll gain a lil power as well



How do you do this? How can i explain this to my mechanic and did it work well for you?

Bianca


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## Nickaltima (Jan 11, 2008)

bcgonzal15 said:


> How do you do this? How can i explain this to my mechanic and did it work well for you?
> 
> Bianca


OBX Exhaust Headers 02-06 Nissan Altima 2.5L ALL S SL - eBay (item 190508761594 end time Apr-03-11 13:27:54 PDT)

pretty much print this out and show him he'll know exactly what your talking about and if he doesn't lol find a new mechanic..and if its going to cost you more than 200 bucks to get it done find a new one lol cause its not to bad on the 4 cylinder..hope this helps you


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## doc4bax (Jan 16, 2009)

Nickaltima said:


> OBX Exhaust Headers 02-06 Nissan Altima 2.5L ALL S SL - eBay (item 190508761594 end time Apr-03-11 13:27:54 PDT)
> 
> pretty much print this out and show him he'll know exactly what your talking about and if he doesn't lol find a new mechanic..and if its going to cost you more than 200 bucks to get it done find a new one lol cause its not to bad on the 4 cylinder..hope this helps you


You dumb ass, a mechanic isn't going to remove the pre-cat and put a header on. It's illegal. Are you retarded?


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## Nickaltima (Jan 11, 2008)

doc4bax said:


> You dumb ass, a mechanic isn't going to remove the pre-cat and put a header on. It's illegal. Are you retarded?


no im very much not "retarded" as you so childishly put it..and you most certainly are right no legit repair shop is going to put a header on with no cat (me using your own term here) are retarded for replying to this thread like you did..call nissan and ask them if they will put a nismo header set on..ill bet you everything you own they absolutely 100% WILL and this requires removing the cat(s) like i said..as long as you replace it with a cat that meets EPA standards WHICH MINE HAS stock from hotshot BTW and is 500% legal..ALSO any repair shop period will put a set of headers on ANY CAR as long as it has a cat on the down pipe(hence why they make high flow cats) or anywhere else they can put it..i called quite a few shops to get prices before doing it myself..idk where you live so think before you type:thumbdwn: ALSOOOO i forgot this part..my car stock comes with 3 cats..i have 1 high flow now and it passes NYS's stringent emissions inspection with out a single issue also i have NO check engine light..smart ass


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