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Piston Rings


RobT

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Festive Greetings to all on the forum.

I'm about to get an MX5 engine to upgrade my 1.6 to a 1.8. As such the engine I'll be getting will be from something 20 years old so I'd like to give it a little refresh before fitting. This means  giving things a lick of paint and renewing gaskets and keeping it standard right now.

My question for you is whether there is much value in replacing the piston rings before it goes in. I'm guessing that the rings wear out long before the cylinders and pistons but could be wrong in my assumptions. Your opinions on this would be valuable.

Also if I do replace the rings then are the aftermarket ones good enough or would you guys that have engine build experience just go with original Mazda parts - or any other reputable makes.

It's my first car engine build and I'm trying to future proof the possible addition of a supercharger in another year or so. This is why I would like to start with as good a standard engine as I can get. 

Wishing you all a fabulous Christmas, Happy New Year, and a lucky 2019.

RobT

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If the engine has problems related to the rings, replace them with OE and a light hone. If not, leave alone.

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I would do a compression for starters,  even done cold it can show up a problem.  Then remove the head and inspect the bores for marks and shoulders at the top of the bore. Mileage and previous oil servicing will have major effect on how worn the engine is now.  With an engine mileage of 80k. miles Japanese engines last well and with minimal wear, some would say it's just run in.  

As for new parts, buy from an established local engine re-conditioner, they will know which brands are not made of cheese or oe Mazda parts of course.  Ask our local Mazda heroes Dave and Barry as well when the time comes for changing bits.

 

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Quite agree with both of the above, only thing I'd add would be replace all the oil seals & any O rings etc. on crank and cams as they tend to go hard with age, even if they aren't worn from use.

It's very easy to talk yourself into spending lots of money that the engine really doesn't need  - been there myself. Unless its done serious miles of been abused with poor servicing, I'd be surprised if it needs rings though.

Depending on miles, could benefit from having the head stripped, valve stems/guides checked and seats/valves cut and new stem seals. But, check first with a compression check as suggested - it might be absolutely fine.

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Worth taking a look anyway.  With my 1.6 engine, there was a little bit of scoring on one of the pistons (I believe as a result of the standard coolant route being slightly less effective at the back of the engine) to the point where I replaced the entire piston, not just the rings. Also got the bores honed at the same time. If you're disassembling the engine anyway, it's probably no harm to take a look.

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Cheers guys. Well the first thing I'll be doing is a compression test. I really want to take it apart but if they are all good then I'll just give it a lick of paint.

Merry Christmas to you all:xmas:

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Hi Rob just remember that a compression test isn’t conclusive. It only tells you the state of a cylinder. The next stage is a leak down test. That tells you if it’s piston rings or inlet or outlet valves. Much more precise. Cheers 

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Robbo I have a leak tester which is the most accurate test, your welcome to borrow it, you will need a compressor to drive it.:yes:

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