Should I repair wife’s SUV or cut my losses?

Hi all!

My wife has a 2018 Infiniti QX60 85k. Timing chain noise…then check engine codes popped with $7E8: engine and 7E9: A/T. My local mechanic said it was the oxygen sensor and to go to the dealership.

Infiniti did their own diagnostics and concluded that there is sludge in the engine. They let me know that if they change the sensor, it may come up again in the future, and that the timing chain issue could also be cause by the engine sludge and reoccur if I change it. We changed the sensor and it passed inspection.

Now after about 6 weeks, the check engine light came up again with the same codes. Using my basic code reader, it also brought up “Random/Multiple Misfires Detected” and “Crankshaft-Camshaft position correlation Bank 1 Sensor B”, which I assume relates to the timing chain?

Just dumped 2k into all sort of front end issues too before all the engine problems. My wife is rough on this car although she’ll swear she’s not LOL. She also idles the car quite a lot waiting for the kids at practices and whatnot.

Not sure I trust my local mechanic with these issues and the dealership is ridiculous $. Maybe an engine specialist?

Would you give me some advice on whether you think this is worth the repairs or should I start looking for a new vehicle?

Any advice would be appreciated!

Thanks!

Although I prefer a newer vehicle, if you’re saddled with the situation that you describe above, I think it would probably make sense to keep the current vehicle. Yes, a new vehicle would come with warranty coverage, but if any issues arise that can be attributed to “abuse” or misuse of the vehicle, then the warranty wouldn’t apply to those issues.

Regarding the sludge problem, that is almost surely due to not having the oil changed often enough, so whether you stick with the current car or buy a new one, please make sure to have the oil changed as per the mfr’s maintenance schedule–which includes an elapsed time factor, as well as the more obvious odometer mileage factor. A lot of idling means that the oil should be changed more often, IMO.

No matter what you choose to do, good luck with the decision!

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What does the wife want to do ? A vehicle that is like what you have is expensive . Might be a good time to find a different repair shop .

It’s possible the noise that sounds like a problematic timing chain actually isn’t the timing chain, but rather the variable valve timing (VVT) actuator. Ask your shop to check the function of that part. A faulty VVT could cause all of these symptoms.

How many miles between oil and filter changes?

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I would try some Marvel Mystery Oil (follow the directions) add it about 500 miles before your next oil change, maybe change the oil using it and run it a 1000 miles a few times to see if it helps any… It will either help or it want… I’ve have seen it work wonders on sludged up engines… Make sure you are changing the oil regularly with the correct oil, if your wife is doing a ton of idling, then I would cut her oil change mileage intervals way down, maybe even in half as long as she is doing that much idling…

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Excessive idling is hard on an engine and can cause the oil sludge if not change regularly.

Used engines are around $5000, expect to pay about $10,000 to replace the engine. An engine specialist could disassemble and clean the engine, replace the timing chain components, pistons and rings, this will cost a little more.

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A friend of mine has either a QX60 or QX80, I think it is. They bought it used; the wife just had to have a full size luxury SUV.

One of the headlights recently went out. My friend tried to get a new bulb. Apparently you have to replace the whole headlight assembly for like $1500. He hit the roof.

My thoughts?

  1. You buy a “luxury” car, you better be ready to pay luxury repair prices.
  2. Does your wife really “need” a luxury SUV?
  3. If she has a tendency to idle the engine for long periods and treat the vehicle harsh overall, that’s not going to change if you get another one.
  4. I tend to think you’d be better off keeping the one you have.

Good luck. I really don’t mean to sound snarky; I’ve been married a long time too, and I recognize there are some battles that are just better left not fought.

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Not sure about that, work trucks may idle 5 out of 8 hours, regular oil changes, course only 30 years watching vehicles come and go.

How often did you change the oil?

Regular oil changes or severe service oil changes?

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Guilty as charged. My wife normally lets me know when the oil change notification pops up on the display, but the last one she didn’t. So it went quite a bit past that. A few others may have gone past 5k. Not blaming her, it’s on me to know when it’s due, but I’ve got 4 cars to maintain and I’m busy with my business, and I dropped the ball. She puts on lot of miles on it mostly in stop and go suburban driving, and of course the idling. I’ll tell you what tho, I’m changing the oil every 3k from now on all our vehicles. Expensive lesson. I knew better.

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Oil changes are often deferred for a month or three, I have performed many oil changes for customers @ 12,000 to 15,000 miles.

After you stated “sludge”, we shouldn’t need to ask “why”.

Reman engine for $5,450 from AAA engines out of Los Angeles, there may be others on the market but I haven’t found examples yet.
Infiniti / Nissan AWD 3.5L Remanufactured Engine QX60 Pathfinder 2017-2018 – AAA Engine

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If you go the new/reman engine way, Jasper engines come with a nationwide 3 year 100K mile transferable parts and labor warranty… And they have been around since 1942…
Just another place you can check out…

And car-part has used engines in my area from 7-110 miles away for $3200 to about $5200 with 80 additional pages of them, seems like there are a lot of 2017-2020 vehicles with your engine sitting in salvage yards…

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Many years ago my Lincoln had a broken tail light. I stopped at the dealer for a new one but they wanted $80 for it. A ford would have been maybe $15. I never bought it and traded the Lincoln. Just not my cup of tea.

Infinity and Nissan, the same company as you know, have slipped dramatically in the reliability department, they are now rated in the lower 25 percentile of all cars made, this all started back in 2010.

I seriously doubt that one prolonged oil change caused sludge. What happened is the poor design of the direct injection system. Direct injection engines, fuel is injected directly into the combustion chamber under high pressure, which can cause carbon buildup. This can mix with oil to create a sludge-like substance that can clog oil passages and reduce lubrication. In doing so it will give your engine a shorter life than what you would expect out of it. And the knocking noises you might be hearing, I say might be hearing because I’m not there to hear it, but that noise is from the sludge build up.

Unfortunately here is the bad news. That knocking sound means it’s too late, the engine is basically toast, it doesn’t have long to go and then you’ll need a new engine at a cost of around $10,000 to $12,000 with a one year warranty, or you could find a used one, but there’s no guarantee that a used one isn’t already sludged up, but the companies that sell used engines are suppose to check them thoroughly before selling them, and they should come with a one year warranty, but that used engine with labor will be around $5,000 to $6,000 dollars.

The other issue with those SUVs is the transmission, at a cost of around $4,000, and the transfer case, which is around $6,000, they were not known to last long, so you could be replacing an engine this year, and the next the transmission! The total of the engine, transmission, and transfer case you could find a really nice used car!

I suggest you cut your loses and soon, and don’t buy any Nissan product, stick with companies that have a known track record for dependability, if you want another luxury SUV get the Lexus, or the Acura, but the Lexus is a better vehicle as far as build quality, reliability wise they’re close. If you want to save some money buy a Toyota SUV, they’re better than the Honda SUV. The other brand that is doing well is Mazda, but that one would be my third pick.

Buy a car that has very low miles on it, that is at least 5 years old, the internet has several car sites that you dictate the mileage and the age. For example, I bought about 4 months ago a 2002 Lexus SC430 with just 34,000 miles, for less than $10,000, it was garaged kept, all maintenance records from a Lexus dealership showed it to have oil changes based on months since it wasn’t driven much in the way of miles, and the car runs fantastic, for some reason it gets better MPGs than the sticker says, about 4 mpg more.

If your patient person you will find a good deal for what you want. The car I bought was a my retirement fun car, took me about a year to find it, but I did the same thing about 5 years ago when I needed another pickup, after 4 months of looking a 2010 Toyota Tundra SR5 4x4 with the 5.7 flex fuel engine with just 87,000 miles came up on a labor day sale, no place came close to the price I got it for, I ran down as fast as I could before they even opened. Patience is the key. If you can wait for labor day, which is coming soon, be looking at the internet sites like a mad man, then rush down real early in the morning, take the day off from work if you have to, because other people are seeing those cars too. Labor day is Monday the 2nd.

When I search for cars I try to buy locally, but where I live prices are for some odd reason higher then they are just 150 miles away. I did get lucky with my Acura and my Toyota and found those locally, but the Lexus, being a difficult to find car, I had to travel 155 miles to see it.

I know if you work those internet sites correctly you will find a nice used car with low mileage. All my cars were bought from dealerships, not private parties, and I only service them at the corresponding dealerships in my town, I have great dealerships, but a dealership understands their make and models better than a independent mechanic, and in some cases, as you found out, the independents can’t fix it. In some cases the independents are not the cheapest, when I had my Acura TL timing belt replaced I got independent quotes between $1,300 to $2,200, the Acura dealer did it for $980 (those prices was just before the huge jump in inflation, now those prices have almost doubled). Also when it comes time to replace the plugs, the dealerships will charge you about $60 a plug, you can buy your own for around $15 and take the plugs to them to install, most dealers will use your plugs, but you have to check with the dealer. My Acura dealer, and my Toyota dealer had no problem using my plugs, but that saved me a lot of money when you consider 6 plugs for one and 8 for another!

Enough rambling, hope you find a vehicle both of you like.

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Find someone who can clean the sludge out of the engine, and replace the timing set–including the timing chain(s), tensioner(s), guides, etc. If that costs a few K, and extends the life of this vehicle by a few years, it would be worth it. That’s less than 6 months of loan payments on a new(er) vehicle!

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The only way to tell if there is sludge in the engine is to remove the valve covers, I seriously doubt that the dealer mechanics did that unless you paid a high diagnostic fee.

The variable valve timing mechanism is very sensitive to dirty oil and that may be what they are basing their diagnosis on. But you could have a bad cam position sensor, that is rare in a vehicle this new as they don’t wear out. They just sense notches in the back of the cam as it rotates.

If this were mine, the first thing I would do is an oil change, even if you just recently had it done. Do it again and plan on doing it again in another 1000 miles. Oil is one of the best solvents for itself as it doesn’t release a lot of contaminates all at once. It is a gentile removal. If you are having it done, check the dipstick before taking it in and then again right after. Unless the before oil was very clean, there should be a difference.

It is also possible that if you had an oil change recently, they facility you used could have used the wrong grade of oil which would cause all the problems you are seeing.

You do not have to go to the nuclear option (new engine) as the first choice for repair.

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