PU. What is on my pistons? W/Pics

[kaminski54]

Here is the short version of my engine problem... any other questions, please ask.

I bought my 2010 Maxima used with 18,000 miles on it. One previous owner... I've used nothing but Pennzoil Ultra 5w30 since I owned it. All UOA have shown low wear with no problems.

I heard a knocking noise and researched the problem discovering a TSB about the problem being the #1 main bearing. I had also discovered a head gasket leak, but it was an external leak so no effect on the inside of the engine. I dropped the car off at the dealer and was told the head gaskets would be replaced and that they would look into the main bearing TSB.

I received a call from the service manager today stating that upon further review of my main bearings, there is significant wear on #1 and #4. He called Nissan and asked how they wish to proceed. Nissan stated they want the engine shipped to them for investigation and they would be sending a new short block for replacement.

I have taken extremely good car of the car... 5000k synthetic oil changes... oil analysis (all stated below average wear)... nothing but Shell premium 93... 90% highway miles... and never abused the car, usually accelerate at about 2500k rpms. I did buy the car used with 18k... it's last mile was just over 41k. Due to my oil analysis results, I have to attribute this to the original owner or maybe I just got a Friday afternoon engine.


Here are some pics I took at the dealer...

What is wrong with my piston tops? Some have said carbon... others, sludge but the rest of the engine is pristine.

Any comments would be appreciated.

 

[ls1mike]

Carbon and to me it looks like your headgasket wasn't just an external leak. Couple of my turbo Dodges looked like that after a blown headgasket. This a 41,000 mile engine?

 

[morepwr]

It looks like carbon on the pistons to me. Did the engine use any oil? A couple of the pistons appear to have a little more carbon than the others. (rear piston in the top pic)Other than that, it does not look abnormal.

If there is a TSB on the #1 main bearing I would assume that there is a known problem with these engine and the result isnt anything you did wrong.

 

[zanzabar]

And used oil analysis all looked good? Baffling. Can you post some of the numbers?

 

[Quest]

shxt happens and your piston looks mighty fine to me (those carbon deposits looks normal IMHO).

If your engine happens to throw a rod/bearing because of factory defect, so be it. Accept it as-is. So long as the manufacture take care of you promptly.

While this may sound like bashing(disappointment), fact is, IMHO Nissan hasn't been all that great since the late-80s/early 90s, with lots of mech issues associated with their stuff....

(*don't give up hopes yet..let's see what the manufacturer/dealer has to say about your engine*)

Q.

 

[tinmanSC]

Ok, I'm totally getting flamed for this... but I have to point it out anyway. I'm a glutton for punishment. I've seen this on a caddy once. Oil changes regularly, babied acceleration, dealer couldn't figure out what was happening with a knocking sound in the engine. Turns out this phenomenon was known to GM about the Northstar. Carbon would build up in the combustion chamber when driven very gently and could cause a knocking/tapping noise as the top of the carbon build up on the piston just barely contacted the bottom of the head. The remedy: Drive it like you stole it for 15 minutes. Carbon burned away, sound was gone.

Good, now that's out of the way. I blame it on a bad PCV valve.

 

[bvance554]

Rest of the engine is pristine? Lol! Its got two bad bearings. I'd hardly refer to it as pristine.

 

[kaminski54]

Originally Posted By: ls1mike
Carbon and to me it looks like your headgasket wasn't just an external leak. Couple of my turbo Dodges looked like that after a blown headgasket. This a 41,000 mile engine?


Yes... it HAD 41,000. New short block has about 1,000.

 

[kaminski54]

Originally Posted By: zanzabar
And used oil analysis all looked good? Baffling. Can you post some of the numbers?


Sure I'll upload tomorrow.

 

[kaminski54]

Originally Posted By: Quest
shxt happens and your piston looks mighty fine to me (those carbon deposits looks normal IMHO).

If your engine happens to throw a rod/bearing because of factory defect, so be it. Accept it as-is. So long as the manufacture take care of you promptly.

While this may sound like bashing(disappointment), fact is, IMHO Nissan hasn't been all that great since the late-80s/early 90s, with lots of mech issues associated with their stuff....
(*don't give up hopes yet..let's see what the manufacturer/dealer has to say about your engine*)

Q.


It definitely was a defect, at least the #1 bearing. Who knows with the #4. The head gasket too. And the manufacturer did take care of me... surprisingly easily... I would have expected that they would want oil receipts or something, but they didn't question anything... just replaced the short block.

As far as Nissan... it is my first one, so I can't argue with your opinion.

 

[kaminski54]

Originally Posted By: tinmanSC
Ok, I'm totally getting flamed for this... but I have to point it out anyway. I'm a glutton for punishment. I've seen this on a caddy once. Oil changes regularly, babied acceleration, dealer couldn't figure out what was happening with a knocking sound in the engine. Turns out this phenomenon was known to GM about the Northstar. Carbon would build up in the combustion chamber when driven very gently and could cause a knocking/tapping noise as the top of the carbon build up on the piston just barely contacted the bottom of the head. The remedy: Drive it like you stole it for 15 minutes. Carbon burned away, sound was gone.

Good, now that's out of the way. I blame it on a bad PCV valve.

I have to admit, I drove it way too gently, so your theory is probably correct. Now that the new block has been broken in, I'm pushing it into the 5-6 thousand rpm range daily.

I've driven two cars very gently, maintained them both without fail... both ended up having major problems. I've decided to have fun driving from now on... going easy didn't do me any favors.

 

[kaminski54]

Originally Posted By: bvance554
Rest of the engine is pristine? Lol! Its got two bad bearings. I'd hardly refer to it as pristine.


OK... it LOOKED pristine from what I could tell before it was gutted.

 

[Hyde244]

^ However, if you indeed have been driving 90% of your mileage on the highway, that is the more than enough time to prevent potential carbon build-up from low rpm/city driving.

Let's wait to hear back from Nissan - could very well be a manufacturer error and not user.

 

[bvance554]

I gotcha, just having fun. I'm sure its a defect of some sort. Any engine with any kind oil change, even sporadic should last 41k unless it was run without any oil at all.

 

[Noobie]

Whats more interesting is that this didn't show up in the used oil analysis.
So this means that used oil analysis are not 100% reliable . . . im not saying they are useless.

 

[Kool1]

Nissan stepped up to the plate. I wish all manufacturers acted in the same fashion.

 

[INDYMAC]

Originally Posted By: Noobie
Whats more interesting is that this didn't show up in the used oil analysis.
So this means that used oil analysis are not 100% reliable . . . im not saying they are useless.


How do you know they didn't show anything?

 

[demarpaint]

Originally Posted By: Noobie
Whats more interesting is that this didn't show up in the used oil analysis.
So this means that used oil analysis are not 100% reliable . . . im not saying they are useless.


used oil analysis reports are not 100% reliable, however they should have indicated that the bearing/bearings were going. I'd love to see the OP's used oil analysis reports. Keep in mind if the OP only had one used oil analysis report and the bearing/bearings went out to lunch after that we can't blame the used oil analysis report for not showing signs. OTOH if he had a series of used oil analysis reports, that would be another story and a great topic for discussion.

 

[Hokiefyd]

Originally Posted By: kaminski54
I've driven two cars very gently, maintained them both without fail... both ended up having major problems. I've decided to have fun driving from now on... going easy didn't do me any favors.


Good for you!

Cars are meant to be driven. Engines are meant to be revved. I owned two Cadillac Northstars, and they did use very low friction piston rings that would tend to get coked up with deposits if not exercised. Mine never had that problem; I drove them like they wanted to be driven. But all the blue-haired grannies out there would end up with oil-burning engines because they drove them like they did their old Town Car.

Keep the RPMs up on that new engine and let it run free.

 

[KrisZ]

Originally Posted By: bvance554
Rest of the engine is pristine? Lol! Its got two bad bearings. I'd hardly refer to it as pristine.

Yes, but it was "factory clean" thanks to PU.

This is one more reason why used oil analysis are so overrated and cannot be used for anything else other than determining oil life, unless very detailed trend analysis is done and that means a lot of used oil analysis and still only educated guesses about engine wear.

Also, this is a good example how synthetics are also overrated. We often hear that people use synthetics to have "extra margin of safety" or because they protect better. Well where is this superior protection and extra margin of safety here?
If things go south because of manufacturing defects or factors outside of oil system, no oil will save that engine.
It's about time people understood this instead of repeating marketing baloney.