Lost an engine, rebuild, replace, scrap?

Joined
May 10, 2005
Messages
2,098
Location
Jupiter, Fl
One of my favorite cars, My '06 Infiniti FX45 had two intake runner butterfly screws go through the motor. I don't know when the first one went through, but the other night I was sitting at a traffic light and heard a car making a horrible knocking noise, the noise disappeared when the ford truck and I left the light, I didn't give it another thought. A couple hundred miles later I heard that horrible noise again, pulled over and could tell that it was coming from the left bank near the head - from prior experience, it sounded like something fell in the motor, but that was not very likely. I was then thinking that the CVTC cam gear or a chain tensioner was failing - as I have heard similar noises from this type of failure. I was in a bad spot and figured that even if I could drive just a mile up the road, my kids and I would be less likely to be attacked. I started driving, within a minute or so (of stop and go traffic) the engine was silent again. I drove the rest of the way home, about 50 miles, on backroads that I could easily coast off to the side if required. The noise never came back. Obviously, I knew something was wrong. I pulled the left VC off, everything looked fine. The intake came was not able to be moved freely, so at the very least, the locking pin was locked in place. I pulled the plugs, they all looked OK. I stuck the camera down the front left hole (#2) and the piston top looked ok. This engine has always had a lot of oil in the chamber and has never really had carbon deposits stick to the pistons. I compared it to pics I took a few years ago, could have been similar. #4 looked like it may have been chewing on some small stuff, or possibly detonation damage, same with #6. #8 had obviously just had a screw bouncing around in it for some period of time. The quench area on the exhaust side looks like a small mountain range. I couldn't see any damage to the intake valves or seats. I could not get a picture of the exh valves or seats (yet). That cylinder seems to have more oil in it than the others, but I think it has always been the wettest. Everything on the right side looks normal. Luckily, I never touched these screws, so at least it isn't something I did (nor is it oil related). For some background, the interior of the car is in very good condition, it is a two-tone dark brown leather and black that I like and is fairly uncommon. The body has no dings or dents. A few scrapes on the front bumper. It drives exactly the way I want it to, and it tows my trailers perfectly. I develop sentimental attachments to my cars, BTW. About 10K miles ago, as a preventative measure, I replaced the water pump and radiator (this generation of Nissan has a slight tendancy to mix ATF with coolant) and hoses. I also replaced the front lower control arms with new OE parts as the old ones were starting to make some noise. So, the car has ~185K miles on it and up to this point has had almost no mechanical failures. The A/C, Adaptive Cruise, Transmission, nothing like that. The only issues have been brakes, tires, wheel bearings, and a starter. I replaced the front driveshaft at around 140K because they are a known weak point which take out nearby parts when they fail. So, my options now are: Drive it as it is and let it eat - maybe pull back the timing a couple of degrees to make detonation less likely on my newly chewed up piston. Maybe I'll get 6 months? I wouldn't trust it. I just returned from a 3K mile trip through the mountains a few weeks ago. Get a Junkyard motor - these seem to be around $2-$2.5K for 100K engines. In general, these engines have a history of throwing rods if they are not maintained perfectly. I would figure another $1,500 for refresh parts and install help. If I could get oil pan or under valve cover pics I would be more comfortable with this. Do a partial rebuild myself - the parts for this motor are quite expensive. Just a set of OE pistons and rings and timing kit and a mix of OE and aftermarket seals/gaskets is more than the price of a junkyard engine. I would still need the machine work. That doesn't include the heads, which have titanium valves. I don't know what the service life is of Ti valves in an ideal world. If they bit on a screw once or twice... Sell it as drivable, but needs a motor and/or take it to the scavenge yard that gives me the best price. I could also sell a couple $K worth of parts, but then I would be left with a hulk of a vehicle stuck in my garage that would need to be dragged out to go to the scrapyard. My thought is that if I put $4K into it now w/ a junkyard engine, the engine might be good? The transmission will probably fail within the next 2 years, requiring replacement/rebuild. So if I set aside $10K for repairs for the next two years (about 35K miles) I paid ~$23K for this car almost 10 years ago. My replacement options are pretty much limited to the FX50 or QX70 V8 w/ the sport package and adaptive cruise/tech package in a color other than black. They are unicorns and priced appropriately. Frequently, clean low mile units that are 5+ years old will show up for $30+K a thousand miles away. Lower priced cars have over 100K miles already. My budget for a replacement car right now would be <$20K unless I finance some of it. I don't like the idea of having a car payment - at least not now. I could buy a used minivan and give up on the SUV that handles well on tight curvy roads. It's also a quandary because I don't like the way the newer cars look, but I like the way they drive. Luckily, I have an extra car that can become my DD while I figure out what to do. Logic tells me to throw in the towel on this car, I'm just afraid of getting a 100K mile 'newer' one that needs a similar amount of work and/or is less reliable. If anyone has any insight, I would appreciate it. I am also afraid that I will run into ancillary issues after pulling/replacing the motor, like A/C issues or other random stuff. I will try to attach pics of my 180K mile valvetrain and the missing screws.

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Joined
Apr 27, 2010
Messages
13,602
Location
Suburban Washington DC
Don't throw good money after bad. Whatever got sucked in may have burned up and came out the exhaust. Keep driving and don't worry about it. If the noise comes back, deal with it then. Spending money to replace an engine on a high mileage 13 year old car makes little sense.
 
Joined
Oct 17, 2014
Messages
2,341
Location
SW Ontario Canada
I'd tear down the engine to see the extent of damage and then make your plan. Yes it's an older car, but as you said it does everything you ask of it, so sentimental aspects aside, get it torn down to see how bad it really is before you part ways.
 
Joined
Jun 26, 2003
Messages
12,685
Location
Illinois
Drive it the way it is. As long as it passes emissions and isn't guzzling oil, drive it until it doesn't drive. It could be relegated to spare car status. Any money spent would be gas, oil and scheduled maintenance. Heroic spending would go towards a replacement vehicle if this were my car.
 

NO2

Joined
Sep 6, 2012
Messages
968
Location
Michigan
We usually keep our cars for a long time. But $4K for a used engine likely to fail - not a rebuilt - seems like too much. Whatever you do this model is a lemon. We had a Nissan V6 with repeated exhaust manifold bolt issues. After the 4th repair, we dumped it. I'd change my expectations. Get a more reliable brand model. There is plenty of data in Consumer reports. Your car is almost 14 years old, and you could pick up a very nice 3-5 year old vehicle for 10-20K that is better than your current model. 10 years is 2 generations nicer in car land. Motors are smaller and a lot more powerful. Infotainment systems work with your phone. Mileage has improved. Part of the problem is that parts for low volume luxury models are very expensive. Your better off getting the high-end trim version of the 'regular' model from the same manufacturer. Most of the difference is in dealer experience and advertising anyway.
 
Joined
May 9, 2005
Messages
443
Location
Nevada
I would see what your compression numbers are, as well as oil consumption and likely just try to keep driving as is. It's amazing the beating that some engines can take, and keep on ticking. If it blows, then it would be time to replace the engine with a junkyard unit.
 
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Joined
Aug 26, 2009
Messages
2,892
Location
PA
I would drive it into the ground, or atleast drive it and see what changes. My old accord had a spark plug break apart around 240,000 miles. It went from a perfectly running car that burned no oil to a perfectly running car with a gouged cylinder wall burning 1 quart every 900 miles. Oil consumption increased over the remaining 146,000 more miles I drove that car. Until it threw a rod at 386,000
 
Joined
Dec 24, 2011
Messages
12,941
Location
North Carolina
New screws with loctite (high temp) and drive on. Deal with a dead engine when you have a dead engine. Yours just got a little hungry, and seems satisfied for now.
 
Joined
Dec 31, 2017
Messages
12,553
Location
SE British Columbia, Canada
Let's see. Thirteen year old car with 185,000 miles. The wrecking yards are full of such cars. If you have a use for it, I'd run it until it's done. You might try a tank of premium to see if it makes any difference. smile
 
Joined
Jul 4, 2016
Messages
2,008
Location
Jacksonville, FL
So it runs, drives, is somewhat injured, too expensive to fix properly, too risky to slam a junk yard engine in it without reworking the engine before installing, and you no longer trust the vehicle. I can't help but think RUN. Better yet, drive, to the nearest Car Max for a buyout offer, or to a car lot to trade it in while it still runs and has some value. I can't see how putting any money into it is anything other than throwing good money after bad.
 
Joined
Jun 14, 2011
Messages
3,356
Location
Texas
Originally Posted by rooflessVW
New screws with loctite (high temp) and drive on. Deal with a dead engine when you have a dead engine. Yours just got a little hungry, and seems satisfied for now.
+7 Run'er until she blows. You have nothing to lose. While you have it apart, loctite ALL of the screws.
 

AZjeff

$50 Site Donor 2023
Joined
Jan 14, 2011
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7,374
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in Az where the Deer and Antelope play
Originally Posted by FlyNavyP3
I can't help but think RUN. Better yet, drive, to the nearest Car Max for a buyout offer, or to a car lot to trade it in while it still runs and has some value. .
And pass on a high probability engine failure to someone else and let Car Max take the heat. Nice.
 
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dishdude

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Nov 14, 2008
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Phoenix
So other than the noise that's now gone, there's no evidence of any damage? You might have got really lucky. I'm going to bet those tiny screws passed through the valves without any damage and what you heard was the butterfly bouncing around in the intake. 13 year old car with almost 200k on it? Not worth putting any money into. Sell it and move on, or drive it until something catastrophic happens and send it to the bone yard.
 
Joined
Nov 9, 2008
Messages
20,909
Location
NH
I think I'm in the "time to bail" camp. Just how much does it owe you? Let it be someone else's problem. Assuming you can move on without it being a major cost, that is. If you can't move on, I'd loctite all of those screws, and hope for the best--decent chance it'll motor on.
 
Joined
Apr 27, 2010
Messages
13,602
Location
Suburban Washington DC
Originally Posted by AZjeff
Originally Posted by FlyNavyP3
I can't help but think RUN. Better yet, drive, to the nearest Car Max for a buyout offer, or to a car lot to trade it in while it still runs and has some value. .
And pass on a high probability engine failure to someone else and let Car Max take the heat. Nice.
Carmax ain't going to retail that thing. They'll offer him maybe $1,500 and flip it at the auction for $2,800.
 
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