Starting a youtube channel

[Fummins]

Fummins, thanks for the interesting video!

The caked-up oil scraper rings and piston lower sections, eg. at 2.23, 7.25, etc, and yet free oil escape holes suggest not enough lubrication with maybe not the best oil. The "dimple" at 3.27 near the mark "12" is the dribble hole for lubricating the piston. Maybe a lubrication nozzle could have been better.

@Fummins: It would be interesting to know what sort of oil was used, particularly the oil quality and viscosity, and at what OCI's.

I’ll post the info I can get in a bit. 6k intervals

[Fummins]

I'll post this over on the clacky 2015 engine thread instead.

[Fummins]

[Grumpy Bear]

1.) Much nicer inside! I can see the oil rings were not knackered in this one. I assume it was using less oil? Yes? No?

2.) Can't see in the video but I'm sure you noticed. Was there anywhere in the bore the crosshatch was polished away?

3.) Can you tell us about the timing chain? Little stretch we saw. Guessing that is not ever an issue in these motors with proper care.

4.) You ever check the valve lash before a teardown? Doesn't take much to make a racket. But could be piston slap too.

I'd be interested in how these two drivers differed in their treatment of the equipment.

Nice video. I love these teardowns.

You may like this, From Enginebuilders Magazine: https://www.enginebuildermag.com/201...uffed-pistons/

Question: What is a ‘scuffed’ piston?


Answer:
A scuffed piston is one that has been damaged by rubbing against the
cylinder wall. The metal-to-metal contact smears the metal on the skirt
on the piston and damages the piston.

Scuffed pistons can be
caused by too much heat in the combustion chamber, engine overheating
or inadequate lubrication. The piston-to-cylinder clearances in most
late model engines is much less than it used to be to reduce piston
rock and noise. Consequently, if the piston or cylinder gets too hot,
the clearance goes away and you get metal-to-metal contact.

In
instances where piston scuffing occurred due to a loss of lubrication,
the underlying cause may be a low oil level in the crankcase (due to a
lack of maintenance or an oil leak), low oil pressure (a worn oil
pump), poor oil quality, or oil breakdown (not changing the oil often
enough).

When diagnosing a scuffed piston, note where the piston
is scuffed. If the cause is overheating, the scuffing will mostly be on
the upper ring lands and on the sides near the wrist pins.

There
may also be oil carbon and lacquer burned onto the underside of the
piston indicating it got too hot. Scuff marks on the lower skirt area
often indicates a lack of lubrication (check the oil pump and pickup
screen). Scuff marks on the edges or corners of the thrust sides of the
piston may be the result of bore distortion. Scuffing on both thrust
sides would indicate binding in the wrist pin.

[Eggman]

Great video. Thanks for recording it and thanks for posting it.

[Fummins]

1.) Much nicer inside! I can see the oil rings were not knackered in this one. I assume it was using less oil? Yes? No?

2.) Can't see in the video but I'm sure you noticed. Was there anywhere in the bore the crosshatch was polished away?

3.) Can you tell us about the timing chain? Little stretch we saw. Guessing that is not ever an issue in these motors with proper care.

4.) You ever check the valve lash before a teardown? Doesn't take much to make a racket. But could be piston slap too.

I'd be interested in how these two drivers differed in their treatment of the equipment.

Nice video. I love these teardowns.

You may like this, From Enginebuilders Magazine: https://www.enginebuildermag.com/201...uffed-pistons/

Question: What is a ‘scuffed’ piston?


Answer:
A scuffed piston is one that has been damaged by rubbing against the
cylinder wall. The metal-to-metal contact smears the metal on the skirt
on the piston and damages the piston.

Scuffed pistons can be
caused by too much heat in the combustion chamber, engine overheating
or inadequate lubrication. The piston-to-cylinder clearances in most
late model engines is much less than it used to be to reduce piston
rock and noise. Consequently, if the piston or cylinder gets too hot,
the clearance goes away and you get metal-to-metal contact.

In
instances where piston scuffing occurred due to a loss of lubrication,
the underlying cause may be a low oil level in the crankcase (due to a
lack of maintenance or an oil leak), low oil pressure (a worn oil
pump), poor oil quality, or oil breakdown (not changing the oil often
enough).

When diagnosing a scuffed piston, note where the piston
is scuffed. If the cause is overheating, the scuffing will mostly be on
the upper ring lands and on the sides near the wrist pins.

There
may also be oil carbon and lacquer burned onto the underside of the
piston indicating it got too hot. Scuff marks on the lower skirt area
often indicates a lack of lubrication (check the oil pump and pickup
screen). Scuff marks on the edges or corners of the thrust sides of the
piston may be the result of bore distortion. Scuffing on both thrust
sides would indicate binding in the wrist pin.

This engine started using a little oil at around 300k kms. 1/2qt every 12,000km or so. This one was way cleaner than the other engine!

I couldn't get a picture of the bores but they were pretty polished. I couldn't see any crosshatching.

I've never opened up one of these engines to do any maintenance. Still running stock timing chain, guides and tensioners. I was surprised to see the tensioner was only kicked out about one extra notch compared to the low mileage engine.

I've never checked valve lash on these things. I really didn't think this one's noise was top end but anything is possible. It sounded like it was coming from the lower rear of the engine, which I think is the side that was scuffed the most. It was noisy at light load, when stopped in drive but kinda went away when coasting. The wrist pin engine was noisy 100% of the time. I thought solid lifter clacky noises would be to be fairly consistant but maybe not?

There's another clacky engine that I might replace one day. It's a 2017 with even less miles...I'm pretty sure it was flood badly then sounded like pooh once they got it going.

The driver of this latest 500+k car treated the car well. Inside and out. Put 400k 99%highay miles on it before car got put into city use and passed around bunch of new drivers like the village prostitue then used as a spare until I finally replaced the engine.

The 450k car had the same driver since new. It hasn't been as well kept. Driver was late on a bunch of oil changes, drives it pretty hard from what I'm told. I'm thinking it may have even been run low on oil, not off the stick but the driver just got lazy and wasn't keeping on top of it...And this driver is more than old enough to know better but also too old to care lol

[Grumpy Bear]

This engine started using a little oil at around 300k kms. 1/2qt every 12,000km or so. This one was way cleaner than the other engine!

I couldn't get a picture of the bores but they were pretty polished. I couldn't see any crosshatching.

I've never opened up one of these engines to do any maintenance. Still running stock timing chain, guides and tensioners. I was surprised to see the tensioner was only kicked out about one extra notch compared to the low mileage engine.

I've never checked valve lash on these things. I really didn't think this one's noise was top end but anything is possible. It sounded like it was coming from the lower rear of the engine, which I think is the side that was scuffed the most. It was noisy at light load, when stopped in drive but kinda went away when coasting. The wrist pin engine was noisy 100% of the time. I thought solid lifter clacky noises would be to be fairly consistant but maybe not?

There's another clacky engine that I might replace one day. It's a 2017 with even less miles...I'm pretty sure it was flood badly then sounded like pooh once they got it going.

The driver of this latest 500+k car treated the car well. Inside and out. Put 400k 99%highay miles on it before car got put into city use and passed around bunch of new drivers like the village prostitue then used as a spare until I finally replaced the engine.

The 450k car had the same driver since new. It hasn't been as well kept. Driver was late on a bunch of oil changes, drives it pretty hard from what I'm told. I'm thinking it may have even been run low on oil, not off the stick but the driver just got lazy and wasn't keeping on top of it...And this driver is more than old enough to know better but also too old to care lol

All of that makes perfect sense and explains everything I'm seeing.

When the article says, "Poor lubrication" that word poor is a catch all. I saw nothing suggesting the motor was ever overheated. Looked like oil maintenance was enough for the type of driving done. i.e. oci length and detergent package looked like it held up well. So, in this case poor means a lack of viscosity for the service and/or in addition an oil with a lower AW content. Not enough phos and zinc.

Viscosity is what keeps parts from touching parts. If it were mine, then next barrel of oil would be a *W30 and 6,000K OCI's. But that's me. Your shop, your money.

[Eggman]

All of that makes perfect sense and explains everything I'm seeing.

When the article says, "Poor lubrication" that word poor is a catch all. I saw nothing suggesting the motor was ever overheated. Looked like oil maintenance was enough for the type of driving done. i.e. oci length and detergent package looked like it held up well. So, in this case poor means a lack of viscosity for the service and/or in addition an oil with a lower AW content. Not enough phos and zinc.

Viscosity is what keeps parts from touching parts. If it were mine, then next barrel of oil would be a *W30 and 6,000K OCI's. But that's me. Your shop, your money.

Quick question for you Grumpy Bear: I can understand why you recommend thicker oil - at least I think I understand. But why would you shorten the oil change interval from 12,000km to 6,000 km? What problem would that fix in this example? You conclude the "oci length & detergent package looked like it held up well."

[Fummins]

All the mirage have had 6000km oil change intervals. This high mile car had 12k until it hit 400000km then it went to 6k like the rest. AFAIK Mitsubishi changed piston design in 2017 to try and prevent skirt wear? I’ll tear a 17 apart one day.

[Grumpy Bear]

Quick question for you Grumpy Bear: I can understand why you recommend thicker oil - at least I think I understand. But why would you shorten the oil change interval from 12,000km to 6,000 km? What problem would that fix in this example? You conclude the "oci length & detergent package looked like it held up well."

Good question! The answer has to do with the VII package and not knowing how well it holds up. There are four different basic types and zero info on which one any one company is using.

OCI is 'hand in glove" as Dyson Labs used to say. This second motor Fummins did may very well go 12K without issue but unless I saw a few UOA's on one starting at 6K and knowing people in general do not like to test, I recommended a 'safe' number. That can be certainly lengthened if the result is verified by labs.

Thanks for asking.