Starting a youtube channel

[Grumpy Bear]

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 pistons were changed in 2017 to try and prevent skirt wear? I’ll tear a 17 apart one day.

Do they look like this?

Attachment 26850

https://mirageforum.com/forum/showth...w-compression)

I'm just starting to read that thread.

[Fummins]

I pulled apart the cam timing dingus the other day and it was a pretty simple setup. I was almost wondering if this noise could be caused by the phaser/cam adjuster dingus? I googled mivec noise but couldn't find the same noise on other 4banger engines. Found lots of post talking about clacky engine though. Some said they pulled the cam adjuster solenoid and blew air through it, possibly changed the solenoid too.

I have one 2017 engine with 362k that's pretty noisy too. I ran some cleaner and snake oil crap through it. Dumped in some 15w40 into it and it is slightly quieter but still too loud to call good. I might dink with the cam phaser on this just for sharts. I still think it's piston slap. I'll try to check valve lash too just to say I did. These engines seem to make noises that are way different than normal grown up engines. That first 450k engine sounded like it had top end/lifter noise to me but it had a bad wrist pin.

I'll try to check valve lash from now on before tearing these down just to 100% eliminate(or introduce) that idea. I was hoping to find more obvious signs of where the noise was coming from.

[Fummins]

Do they look like this?

Attachment 26850

https://mirageforum.com/forum/showth...w-compression)

I'm just starting to read that thread.

Just saw this. I think top fuel referenced that same same thread, I looked but didn’t read the first post til now. I’ll dump the original post here:

Hi, early in marsh I took my wife's 2018 Mirage (55000km) to the dealership because of an engine noise that would not go away after the engine had warmed up. They charged me 400$ to do a compression test and tell me that Mitsubishi would not repair it on warranty because the oil change had some time been done 2000 km to late....

After some phone call leading to dead-end, I decided to repair the engine myself as the dealership would charge 3000+$ and I estimated the repair to 400$

Now the engine is out of the car and opened up. The 3 piston have damage to the skirt on one side and the wrist pin are not turning freely in the piston. The cylinder wall have the same kind of damage as the piston.

I would not find any oversized piston for the 3a92 so I ordered a piston set from rockauto for a toyota 1nz. Same bore, same pin, similar valve relief, the compression distance is a little longer. That I will adjust when the block come back from the machinist.

The crankshaft look like new, all the bearing have minimal to no wear at all.

The machinist said that by the look off the piston, the damage would be due to overheating or to excess gasoline.

The engine would flood 3-4 time during the winter and we would have to start it with full throttle. It would smoke black and smell like snowmobile and then run fine. We have never experience overheating with the car.

Maybe the engine would run lean and overheat the piston after the over-fueling event like the 2014-2015 were doing...

I will post picture of everything soon, do you guys have pics request or dimension you would like to have before I put it back together?

Sorry for my English, I live in Quebec, Canada and do not type in English normally.

He mentioned his machinist thinks the scuffing was caused by overheating or gas. I’ll go with gas. The piston in that thread had the same scuffing, worse on one side. That piston looks like the skirt may have some other material where the skirts are, looks like a different color?
I still have a bunch of engines left on the shelf but there are still a few more clackers in the fleet right now and I’m sure more to come. Eventually.

[Eggman]

Seems this problem is due to the piston not sitting square inside the cylinder. Isn't this made worse because the rings are so close together - or put another way, would it be less of a problem if the piston rings were further apart? Just speculating, and I can't remember if this has been brought up before.

[Fummins]

I think making sure these do not flood out is a way to make these things last. I see drivers(and myself have done this)let go of the key before the engine is started and....then they're sometimes flooded. Or when a driver would fire up another persons car to move it out of the way first thing in the morning, they'd fire it up and move it then shut it off un under 30 seconds then when the other driver showed up their car wouldn't start...
There's a few comments in the latest video suggesting that all I had to do was adjust the lifters. I'll try to debunk or prove that next time. One of the best comments is from someone that has what looks like a ford focus avatar...Calling these things junk. Pot calling the kettle black. I guess if you had a bad experience and don't know how stuff works then I get it.

I'm still picking away at a pita Sonic engine replacement. I just found out that the engine that I'm installing has almost 500k kms lol

[Grumpy Bear]

That piston looks like the skirt may have some other material where the skirts are, looks like a different color?

It's a coating used to reduce friction and thus scuffing. It is sacrificial.

Some info on that: https://info.jepistons.com/perfectskirt

OEM's have their own but tis the same idea. Mitsu's version is the 2017 and newer piston shown in that link.

[Grumpy Bear]

I think making sure these do not flood out is a way to make these things last. I see drivers(and myself have done this)let go of the key before the engine is started and....then they're sometimes flooded. Or when a driver would fire up another persons car to move it out of the way first thing in the morning, they'd fire it up and move it then shut it off un under 30 seconds then when the other driver showed up their car wouldn't start...
There's a few comments in the latest video suggesting that all I had to do was adjust the lifters. I'll try to debunk or prove that next time. One of the best comments is from someone that has what looks like a ford focus avatar...Calling these things junk. Pot calling the kettle black. I guess if you had a bad experience and don't know how stuff works then I get it.

I'm still picking away at a pita Sonic engine replacement. I just found out that the engine that I'm installing has almost 500k kms lol

Did I read somewhere on this site a note about Mitsu doing a ECU software patch for flooding?

[Grumpy Bear]

He mentioned his machinist thinks the scuffing was caused by overheating or gas. I’ll go with gas. The piston in that thread had the same scuffing, worse on one side.

Scuffing is always worse on one side. The thrust side. It gets the most load. Part of the Stribeck Curve of lubrication is load. The Hersey Equation. Gas in the oil will most certainly reduce viscosity.

As cold as it gets in your area cold flow is a major issue. Scuffing from a lack of available oil film. Startup then is best served with a low viscosity. Multigrade oils are not all alike. The CCS value for a specific SAE grade is set as a MAXIMUM, not a minimum.

SAE specs for 0W20 CCS is a MAXIMUM of 6,200 @ -35 C and Pumping viscosity of 60,000 cP @ -40C.

Current Klondike 0W20 CCS @ -35C 5,400 cP, pumping viscosity at -40C is 21,000 cP. Well within spec.

Current HPL Premium Plus 0W20 CCS is 3,979 with a pumping vis of 13,211. Much friendlier in cold weather.

Not suggesting you run this, just showing how the same SAE grade can have such a HUGE difference in cold weather performance. Darn few oils even give the pumping number voluntarily.

[Fummins]

Did I read somewhere on this site a note about Mitsu doing a ECU software patch for flooding?

Yeah, it was a recall for 14-15's I believe. If the engine was noisy they'd replace it. My previous low mileage 2014 had this software update done by one of the previous owners(I looked up the records online), but it was a tiny bit clacky when I bought it. When I went to sell the car it was pretty loud so I took it in to the dealer and they agreed it was junk and replaced the engine, no questions asked. I'm not sure if it was replaced under warranty(they never did ask for any service records and it had 30,000miles at the time) or if it was covered under that recall that was already performed the year or so prior to me taking it in. I'll look for the recall.

My current 2014 was bought with 280ish?k kms(I can't remember) and was quieter than my other 14 with 50k km. Until a rod bearing spun....
I don't think any recalls have been done to my current car cause the owner loved his nearby mits dealer as much as I do from what i recall.
I found a lot of these cars still flooded after having the software update done. Less often maybe, but it still happened. I'm pretty sure Foama might have a good work around by tricking the coolant temp sensor iirc.
Recall here> https://static.nhtsa.gov/odi/tsbs/20...03105-0335.pdf

[Grumpy Bear]

Seems this problem is due to the piston not sitting square inside the cylinder. Isn't this made worse because the rings are so close together - or put another way, would it be less of a problem if the piston rings were further apart? Just speculating, and I can't remember if this has been brought up before.

Rings have a 'back clearance" or "duck under" dimension. .0008" to .0010". Gas pressure behind the ring holds the top ring against the wall and the sealing then is ring to ring land and ring face to wall. The higher and tighter the ring pack is the more stable it becomes. Why? The wrist pin is a fulcrum. The lower face of the piston one contact point and the ring pack the other. Both need a film of oil to slide upon less we scuff the skirt or polish the bore. So, the further those two contact points are the more stable the ring to wall intersection is.

Yes there is a limit. Enough thickness to prevent collapse of the areas between the rings and above the top ring.

Did you know that pistons are both barrel ground, top to bottom and ovate at the center? Shows up when you scuff one,




Watch this video on skirt wear from Mahle.

https://www.youtube.com/watch?v=6uK7i4NHuEA