Piston/Cylinder Damage

Good morning all,

Like many of you, I have been plagued by the near
constant engine pinging/detonation issue which has been present in my truck since I bought it used with 24k miles. It's only gotten worse since then, and now has 55k. Yesterday, I replaced the spark plugs for the first time and used a boroscope in the cylinders to assess for any detonation damage, and this is what I found. First impression is tons of carbon build up in some of the cylinders, and a ton of oil in the intake manifold. On top of that, I can't tell whether some of these photos are showing piston damage, or just the carbon deposits flaking off. There's also plenty of noticeable scoring of the cylinder walls.

What would you guys do? I have 5k miles left on my warranty so it needs to get figured out now, but I don't know what my options are in this case. I also suspect a bad lifter, but that's a separate issue in a separate thread.


P.S. these are obviously just photos of the boroscope screen, but I can download the actual files for a clearer look later.

 

From my motocross days looks like foreign matter was injested. Dirt. Why only one bank of the intake oily? What does your pcv valve look like?

 

Never offroaded, filters have been clean, so not sure. Also not sure why only one bank is oily. PCV is completely clean.

 

Bank 2 being oily is pretty normal…many people have taken their intakes off to see the same. I think it has to do with the design of the intake manifold and the oil vapors just happen to land there before they make it to Bank 1.

I can’t speak to the carbon or cylinder scoring though…the scoring is unfortunate.

 

The scoring could have come from the carbon deposits flaking off and taking a ride inside the cylinder

 

That's what I was thinking. I was way less worried about the scoring than the condition of the piston. These things have really wacky shaped pistons, so I just cant tell whether I'm looking at flaking carbon or actual piston damage.

If the piston isn't damaged, I'm thinking that pulling the heads, giving everything a deep clean and installing an oil catch can might really help the pinging issue and get her back on track.

 

Is the pinging maybe due to the fuel you’re using? Have you tried a higher octane fuel and see if the pinging goes away? Might be worth a shot.

 

Yes, running higher octane makes the issue go away almost completely. The issue is, you shouldnt have to run higher octane fuel in the tacoma, per the owner's manual. All my taco friends run regular fuel with no issues at all, maybe a slight ping once and a while under load which per the owners manual is normal and no cause for concern. My issue has been far beyond the occasional rattle unfortunately, so something is definitely wrong, and I think the carbon build up causing hotspots is likely the cause.

 

Have you tried running a few tanks of premium with fuel cleaner to clean things up? Maybe that fancy new Valvoline Restore and Protect to help things along too. The previous owner could have done zero maintenance at all and you could have got it with the factory oil in it.

Otherwise it's not perfect but it doesn't look too bad. What kind of driving do you do? Long commutes, shorter city drives?

 

I'll give the fuel cleaner a shot after I get the dealer's opinion (which I assume will be "take a walk"). I do almost all highway these days. I'm fairly easy on the truck.

 

I would have to agree with you

 

That's fair, things to have a hard time duplicating they tend to push off. Especially since the owners manual says minor knocking is normal.

When/if you try the Premium fuel and cleaner, and/or Restore and Protect oil, it also helps to crack the whip on the truck every now and then like for on ramps once everything is warmed up. Sometimes only driving easy caused problems like carbon build up because the engine doesn't get hot enough to burn it off

 

You sure are coming up with a lot of expensive "repair" ideas for something that is probably not an issue at all. If it was mine, I would put it all back together and drive the fucking thing.

 

"Fairly easy" on the truck? You go speed limit on highway? I not telling drive like Fast and The Furious, previous owner may have driving like old person, real slow, put cheapo gas. Maybe you drive faster, burn carbon.

 

Well, my "fairly easy" is still enough to scare my wife constantly, usually 80+ on the highway and not babying the pedal. My other truck is a Jeep XJ so in my head the taco gets treated like a queen in comparison to how I treat that truck LOL

 

The only thing I can add is to be cautious of borescope pictures. Between the probe lighting and magnification, something fairly insignificant can look pretty rough. I'd hazard a guess that those cylinder walls are actually in decent shape if you did tear into it.

 

Just an FYI, I had to run higher than 87 octane for the 92k miles I owned my Taco. I needed about 89 octane to keep from pinging. Never had any issues and never ran a scope in it, but my plugs looked like yours at 60k or so when I changed them. There should be a pic in my history somewhere. Mine was always a light throttle/low RPM ping from the day I got it new to 92k or so, so mine wasn't a carbon issue, just noisey. I get gas at costco so 87 and 93 is all they have here, so I would usually alternate octanes between fill-ups. Luckily my Tundra does not have this issue.

 

The 87 octane regular makes mine knock and ping as well. I've had good luck with mixing
half a tank of premium with the 87 octane. The gas in NY is notoriously bad period.
Truck also runs better. Its worth a few extra bucks to me detonation is bad for engines.

Is your borescope a cheap chinese one? some of them have terrible resolution.
Your plugs don't look that bad.

 

my thoughts as well. i can still see the oem crosshatching pattern in the walls. from my limited experience on scratched cylinder walls, heavy enough wear to scratch things will generally obliterate the crosshatching pattern.

only real way to know is to pull the heads. and that's not a cheap cost for 'peace of mind'.

i would say that looks pretty normal for a 55k mile motor.