You are probably right but I didn’t buy a 4Runner to start to have doubts at 90k miles. Really pisses me off. I I’ll be doing a compression test by this weekend to rule out other possibilities.

Quaker state full synthetic with trd oil filter.

@BigBlueSince82

I had the spark plug out of this 2003 Highlander with a 3.0L 1MZ-FE engine earlier today, so I snapped a quick picture with my scope (I also see that I need to fix the date and time on it...) It has over 230k on it and mechanically runs very well with no significant oil consumption or mechanical issues (though this poor thing needed a lot of maintenance from being neglected); here's what the inside of the cylinder looks like.

It's not exactly an apples to apples comparison given the 1MZ-FE is a cast iron block, but it uses roughly the same hardening process as the cast iron sleeves in your 1GR-FE block IIRC, so close enough.

Note- I didn't bother rotating the picture, so up is down, down is up.

Attached Images

 

Par for the course with a waste spark ignition system, aka nothing to be concerned about. The sooty buildup on the piston face will increase compression over time lol

Cross hatching on the cylinder walls is normal, from the factory to promote ring seal and proper break in, and over time as the rings rotate in the piston grooves.

If your cylinder walls are not chrome lined (ours are not) and they are smooth as silk, then be worried.

Sent from my Pixel 4 XL using Tapatalk

Thank you, i appreciate the effort. I hope others can share photos for comparison. I’m starting to really lean towards the valve seats leaking. Either way after 90k plus miles I don’t believe there shouldn’t be vertical score lines like this in an engine that doesn’t have future problems on its way.

I'd file this under "Don't worry now, but let's keep an eye on this for a bit".

You can do a Google search and see that this isn't wildly uncommon and in many cases, isn't an issue.

Let's look at the facts with your motor and these motors in general:

1) You 4Runner isn't, and apparently hasn't, exhibited any driveability issues, misfires, oil consumption, smoking, spark plugs look fine, etc.

2) The 1GR-FE dual VVT-i engine is quite reliable. The most common major issue is a failed head gasket, but that isn't very common to the dual VVT-i motor that's found in the 5th gen 4Runner.


A year after I purchased my 2016 BMW M235, it started making a faint noise that sounded just like low rpm rod knock. The short block in the M235 is ~$12K alone. After some research and inspection, it turns out that a combination of the dual mass flywheel and self-adjusting clutch can be quite noisy as they get a little age. I figured out that I could make the sound go away by simply pushing in the clutch pedal. The car has made that sound for the last 5.5 years and 50K miles. Used oil analysis has been perfect. Point being, don't worry until there is really something to worry about.

So I'm tearing down a '19 4runner with about 31k on it to swap out the short block due to an oil galley leak. I got it all torn down ready to swap out and snapped a few pictures for you.

This engine has the same marks and "shadows" along the cylinder walls. You can't feel them with a fingernail or fine tipped pick they look more like burnish marks you'd see when someone superficially scuffs a polished stainless steel plate. My best guess is that they're burnish marks from when the engine originally "seated in/wore in" from minor variances in the roundness of the pistons, rings, and cylinder that are totally within acceptable factory tolerances.

Attached Images

     

You are the best!!!! Thank you very much! I’m sure this topic has peaked some interest on here. I just hope you are 100% right. Keep the pictures coming, I’m interested to see how common this is.

you did the oil changes great and then you looked in to the cylinder well,,,,, I was repairing engines and the bores use a tool to buff it ..your picture works great ...
so you did not loose engine oil ...your engine is very good around 100K miles ..

I checked my 20 with 48k miles....what I found was quite shocking....I did some research and figure as long as I don't feed it after midnight or install a water injection system on the truck, I should be ok.

Attached Images

 

Hahaha, mine was definitely fed after 12! Did you notice any oil in your intake manifold? I have way more then I would like. Definitely need a catch can installed soon.

How much are you filling the engine and how are you checking the oil level afterwards? A little too much can result in some excess getting sucked into the intake via the PCV system.

Fill with 6.5 quarts. Check on level ground. I know the book says 6.6 but I figure there has to be some oil remaining, if not .1 quarts would not make a difference.

Subscribed!

Clearly the answer to is to pull the motor, pull the heads, drop the bottom end and give it a good ol' dingleberry honing.