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Discussion Starter · #1 ·
Quick question:

Anyone know if the cylinder walls in the 2021 sentra engine (MR20DE) are lined, spray coated, EDM, or Plasma coated?

Mostly curious from a durability/servicing standpoint. How long will these engines realistically last and are they serviceable if the walls get scratched?
 

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I assume they are plated only with no iron liner, the 18s are and basically same engine. Can't bore them if so. They last based on frequency of oil changes and I for one think thicker oil extends life in them.
 

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Not sure about the 2.0L in the 2021 'plain vanilla' Sentra having it. The Sentra Nismo does have the mirror finish spray bores.
 

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It's an option used on the CHEAPER line of cars, that should tell you it is on all of them. Liner blocks cost more to make.
 

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It's an option used on the CHEAPER line of cars, that should tell you it is on all of them. Liner blocks cost more to make.
Needed to edit this post to make it unequivocally clear that Nissan is using a bore coating techology developed and patented by the Ford Motor Company that
now can be used in less expensive vehicles.

Actually, up until very recently. the Nissan spray bore cylinder - plasma transferred wire arc (PTWA) thermal spray - cost a lot more to manufacture than inserting iron liners into aluminum blocks.
Nissan originally used the PTWA thermal spray technology only in its very pricey 3.8L GT-R.
Only now has the PTWA trickled down into less expensive vehicles like the Altima.

This could be a BIG mistake if the spray bore doesn't last for 200K miles which I maintain should be considered the minimum life of an ICE in the 2020s.
 

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I would not say the technology flipped from upper end to cheap recently at all. The Chevrolet Vega fiasco caused by similar idea was back in the '70s. Motorcycles did it in the '60s. They've been trying to use aluminum liners with plating or special coatings for easily 60 years, the factory reasons given are cost savings and better engine cooling. Chainsaws have done it for 40 years. I have like 5 of them and all have it and are pretty old. The Nikasil process dates from the '60s.

My Versa has it and easy 10 years ago, Nissan went through a rash of engines with defective plating around '08ish that scrapped many under warranty.

That exact process may be relatively new in detail but the actual idea of it is much older, there being several ways to do it.

I don't care for it as the coating can be hard to get exact thickness throughout and then thin areas can wear out to expose the base metal which is aluminum in most cases. You then get aluminum on aluminum (piston) which is one of the fastest wearing combos you can get, they tend to seize even well oiled and then engine tears up. All it takes is a simple particle of the coating to come loose to start the whole process, a situation that on a normal cast iron liner simply scores a light groove in cylinder wall and engine goes on like nothing happened. I learned to hate those type cylinders when racing 2 strokes. When overheated the coating comes loose in a hideous way that tears up everything; it tends to gouge up on itself in wads mixed with aluminum underneath it has torn loose. The cylinders cannot be refreshed and you toss them. Oh, you can rebuild them by boring but you won't find oversize pistons as the OEMs intend for you to go to another block as they have to be rebored and then replated and nobody commonly does the plating, the cost would be more than a replacement block.
 

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Discussion Starter · #8 ·
Well I've really done some digging and can't find anything about the MR20DE walls being sprayed or plated so I'm going to guess that they're lined. I'm OK with liners but but don't trust the diamond coated spray or plating.

I was looking at a 5.0 Mustang but they've been arc coated since 2018 and after going through their forums/recall history I don't trust it. The coating is only so thick and one you start to get through it or get a scratch on the walls the whole thing comes apart and you can't fix it. Also can't overbore! What's the point of owning a Mustang if you can't modify it? That's part of the fun of owning one!

Having said that I haven't had any issues with my MRA8DE but really don't have allot of miles on it yet.

I'm seriously looking at a new 2021 Sentra for the long haul and this would be a deal breaker.
 

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Well, it's not entirely true that arc sprayed cylinder bores can't be fixed. It's just that you or your local machine shop won't be capable of doing it. It would require removing the spray coating and redoing the bore surface prep, arc coating, and diamond polishing of the bores. So yeah, you would need to order a short block to rebuild these engines and that would be $$$$$.
 

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If they don't intend to rebore them you'll likely find there are no oversize pistons or rings unless you get them custom made. Any shortblocks would be standard bore and by that likely green blocks at full price, they will not be rebuilds. Thinking that engine has free standing cylinders with no deck and may not be enough wall thickness to bore anyway and still remain safe.
 

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That is just more of make it cheap (whether the process is or not cost wise, its still just a cheap idea and to make it less of an option to rebuild, inexpensively ). The biggest problem with all this garbage manufacturing nowadays is, its all about the manufacture cutting corners at our expense. Just look at the garbage engines that the germans produce, "one" most of them don't last long and have major problems, and "two" cost as much as a brand new car (of another brand) to replace. All the modern junk is most always die cast aluminum for major castings, and then sometimes over use of PM materials, yeah super cheap construction and a super high price to purchase. It would be nice if all the manufacturing savings were past on to the rest of us as well.
 

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Yeah, buddy. I got enlightened when I went to parts in '09 and had the idea that Volkswagen was one of the top engineering and QC oriented groups in the world. Boy did that dream get shattered when selling parts to the local VW shop client, he showed me so much garbage built into the cars it was eye opening. The Ford part unitizing strategy started way back in the '90s at Ford taught me too. They turned all the engineers inwards to instead of resolve issues to make them not happen on later models they began instead to come up with new ways to make parts cheaper (NOT for us though!) and with finite life to be able to sell far more replacement parts. Then they began to combine commonly needed small parts of all types into bigger subassemblies costing 10X as much to get the average parts counter purchase much bigger. I was told by the counter guys back then Ford was looking to bump all sub $10 parts into a minimum of $50 parts sales. They also try to make everything they can out of plastic too, it saves them millions not passed on. The plastic valve covers that turn into dust after enough exposure to heat and only priced slightly less than the metal ones. That stuff makes sure no older cars will be around for the kids to drive. Somewhere around 2010 there were upper end diesel engines in trucks that put the entire injection wiring harness under the valve covers to make for a around $500 part that went out left and right. And the stupid design two piece spark plugs that ruined so many engines, it's like they are looking for ways to make massive fails to generate revenue but they got way out of line with the DCT trans, that one now costing them millions.

With Nissan and the way they implement it so dirt cheap the albatross is CVT.

I for one don't even like the mileage saving motor oils now used, they are thin enough to add mileage but that produces other problems they absolutely will NOT say a word about.
 

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Wanna see a boat anchor? The new Nissan VC turbo 2.0 with variable compression. I have to ask.........if a turbo itself is essentially variable compression by way of boost amount, then why on earth did somebody add double the number of parts to make a variable compression engine?? All to increase gas mileage they say but real world it failed to do it. And anybody familiar with the inside of an engine as it wears, please tell me what happens when the top ring groove wear then wears lower down in the most needed spot to make long term average power, those engines will be getting tired way ahead of time and nobody says a word about that in the 500 pages of tech they bury you with bragging about it. And right about then the rod bearings will act like too loose as they are DOUBLED effectively by the use of the eccentric shaft that varies the compression height, you have TWO sets of bearings to wear doubling the wear rate.

Freaking morons designed that engine.
 

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An example of engineering turned inward...........on the Ford zetec engine. The original engine in a Probe used a cast metal thermostat housing. Expensive to cast as it had THREE passages in it. Bulletproof part. OK, so they then cast it in hard alkyd bakelite type plastic on the Contour using same engine. Still pretty reliable. Then they start using same in Focus cars and shortly after the same bakelite part turns into ABS plastic which is nowhere near as strong and has a life shortened by heat exposure. A Focus going to 250K miles can likely expect to have to change two of them, but it gets better. After years of same design somebody redesigns the front stat cover on the housing to now have a notch at the 4 o'clock point, which greatly weakens the thickness of the cover rim at that point, now the front cover can leak and sometimes does even on brand new parts, the ABS flexes to let you visibly see where the notch is letting the cover warp up loose in a spot. Oh, and they changed a perfect triangle bolt pattern on the front cover to another with a weird way lopsided uneven bolt pattern that promotes more leak at the bad spot as well. I also forgot to add that the housing seals on the other end too, a thin maybe 1/8" thick wall juts up and free standing so temperature of hot water can get easily to the back and that wall also heat checks to commonly collapse in pieces to let all coolant suddenly run out of engine to overheat it and it dies. That whole housing is a part guaranteed to bite you on the butt if you do not stay on top of how old it is and no warning given until it blows either seal and you are then stranded.

They made it even 'better' using a fairly complicated cooling fan wiring setup that blows peoples' minds and makes the cars prone to overheating too. Then they made THAT even BETTER by complicating the fan wiring even more, at the last FOUR relays all have to be working right to properly cool them, and why most of what is normally a 300K life engine ends up in the scrapyards with half that mileage, they are typically burned up.
 
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