NC Duratec Engine, How Much of It Is Ford?
Discussion
The MX5 Duratec engine had a pretty poor reputation in both 1.8 and 2.0 configuration, particularly the early ones. The problems start with increased oil consumption due to worn rings, this goes un noticed as the "oil pressure gauge" which isn't actually an oil pressure gauge continues to say everything is fine until the bottom end starts rattling. The "experts" then tell you it's £1000 for a second hand engine which is probably a trip to the shops away from disaster, £2000 for a rebuilt engine or £3000 for a 2.5 litre conversion.
The Ford version of the engine seems to be much more reliable with 200k miles being realistic with the Mazda version letting go as early as 60k.
My NC 2.0 was bought as a project complete with rattling (more like hammering) big ends. When you start looking, the block has FoMoCo (Ford USA) cast on the side and when you start checking for engine parts quite a lot seems to be interchangeable, although the block won't mate up to a Mazda gearbox because it's machined differently and I'm not sure all versions of the Ford engine have the Variable Valve Timing.
So where is the Mazda engine built, is it made by Ford in the USandA? Do they ship bare castings from Ford in the US to Mazda in Japan? Nobody seems to have a definitive answer.
The Ford version of the engine seems to be much more reliable with 200k miles being realistic with the Mazda version letting go as early as 60k.
My NC 2.0 was bought as a project complete with rattling (more like hammering) big ends. When you start looking, the block has FoMoCo (Ford USA) cast on the side and when you start checking for engine parts quite a lot seems to be interchangeable, although the block won't mate up to a Mazda gearbox because it's machined differently and I'm not sure all versions of the Ford engine have the Variable Valve Timing.
So where is the Mazda engine built, is it made by Ford in the USandA? Do they ship bare castings from Ford in the US to Mazda in Japan? Nobody seems to have a definitive answer.
I can help you, as I’ve rebuilt a couple.
Firstly the engine was designed by Mazda not Ford.
Block, pistons, rings bearings ,valve springs, crank, oil pump, water pump etc Are all interchangeable. So you can pop onto Burton power and buy what you need pretty cheaply. That’s how I rebuild mine. (I race them)
Head, head gasket and cams are different, so you have to buy the Mazda gasket set annoyingly.
The issue with them is 2 fold. Firstly when they are driven sedately (Mazdas new are bought by old people) the rings don’t bed into the bores properly, this creates 2 issues. 1 is the rings stick to the piston with carbon build up, they need good cylinder pressure to ‘push’ the rings into the bore wall. 2 as the bores are ali it is easy for the honing to wear away exasperating the issue and creating high oil consumption.
Secondly the original dipstick is a right pain to read and the oil only needs to go slightly low before you run into bearing issues.
That’s it really, the ones I have taken apart have the same issue of bore wash and stuck rings both around 80k miles main bearings were fine. Fix is a complete strip, hone and a head refresh. Mains generally can be re-used if you catch it in time, big ends need replacing whatever. Cost self building is 1k just for machining and parts hence why most just get binned.
You can get lucky with an ‘Italian tune up’ and in stock the rings but this will be temporary due to the bores.
I recently bought one of the last crate engines direct from Mazda, interestingly this engine was super tight and had noticeably limited torque, only now after 1,000 miles half of that on track has it started to loosen up and make good power.
Firstly the engine was designed by Mazda not Ford.
Block, pistons, rings bearings ,valve springs, crank, oil pump, water pump etc Are all interchangeable. So you can pop onto Burton power and buy what you need pretty cheaply. That’s how I rebuild mine. (I race them)
Head, head gasket and cams are different, so you have to buy the Mazda gasket set annoyingly.
The issue with them is 2 fold. Firstly when they are driven sedately (Mazdas new are bought by old people) the rings don’t bed into the bores properly, this creates 2 issues. 1 is the rings stick to the piston with carbon build up, they need good cylinder pressure to ‘push’ the rings into the bore wall. 2 as the bores are ali it is easy for the honing to wear away exasperating the issue and creating high oil consumption.
Secondly the original dipstick is a right pain to read and the oil only needs to go slightly low before you run into bearing issues.
That’s it really, the ones I have taken apart have the same issue of bore wash and stuck rings both around 80k miles main bearings were fine. Fix is a complete strip, hone and a head refresh. Mains generally can be re-used if you catch it in time, big ends need replacing whatever. Cost self building is 1k just for machining and parts hence why most just get binned.
You can get lucky with an ‘Italian tune up’ and in stock the rings but this will be temporary due to the bores.
I recently bought one of the last crate engines direct from Mazda, interestingly this engine was super tight and had noticeably limited torque, only now after 1,000 miles half of that on track has it started to loosen up and make good power.
At last some unbiased advice from someone who isn't trying to sell me a rebuilt engine and keeping their cards close to their chest, thank you. Due to the rust issues this car has, I don't see it has a life of more than 2-3 years, even after rustproofing and welding, so no point spending loads on it.
I'd heard that the Ford/Mazda collaboration on engine design was split with Mazda responsible for smaller engines and Ford the larger ones.
I bought a second hand engine from someone who went the 2.5L route because their old one started to use oil. I've stripped it, the crank looks fine and the bores have no discernible wear. So my plan is to fit new rings and big end shells (actually the mains and big ends look fine), so I just need to get the bores honed.
I'd heard that the Ford/Mazda collaboration on engine design was split with Mazda responsible for smaller engines and Ford the larger ones.
I bought a second hand engine from someone who went the 2.5L route because their old one started to use oil. I've stripped it, the crank looks fine and the bores have no discernible wear. So my plan is to fit new rings and big end shells (actually the mains and big ends look fine), so I just need to get the bores honed.
Yeah I was being told for years how hard rebuilding them is…get it honed while you have it apart. Always worth getting the head properly cleaned and checked if you have an extra £250 kicking about.
Gasket from MX5 parts (if they have any)
New main seals from Burtons, rings from Burtons, big end bearings from burtons, leave the mains, give it all a clean and put it back together.
You need a cam timing kit, available on eBay. Workshop manual is on Mullens.net.
That’s it…easy
Gasket from MX5 parts (if they have any)
New main seals from Burtons, rings from Burtons, big end bearings from burtons, leave the mains, give it all a clean and put it back together.
You need a cam timing kit, available on eBay. Workshop manual is on Mullens.net.
That’s it…easy
So the bottom end rebuild will be completed today and I'm thinking about what if anything to do to the head?
The engine's done about 80k and I can't see anything immediately wrong with the head, the gasket was fine. Is there any practical value in stripping it, doing the stem seals (do they leak oil) and is a skim really required?
The engine's done about 80k and I can't see anything immediately wrong with the head, the gasket was fine. Is there any practical value in stripping it, doing the stem seals (do they leak oil) and is a skim really required?
SweptVolume said:
Do these problems extend into the early ND1's, which I believe had 'the same' engine as the NC? What about the revised 184 PS ND2's?
Completely different, entitely unrelated engine. The Skyactiv is a very modern, high compression, all Mazda design. Absolutey nothing shared from NC to ND engine. https://en.wikipedia.org/wiki/Skyactiv
There is rather a lot of incorrect information in this thread which could be researched via my blog, but briefly:
An engine rebuild is not £2000, but that does depend on how much of it you destroyed in the first place of course.
They don't suffer from pre 1980s bore wash at all, nor do they have aluminium bores (they have iron liners).
They do not have a worn ring problem and are not exasperating.
All MZR/Duratec units have the same issues no matter what car they are mounted in or where they were built.
As far as interchangeable components go from Fords Duratec to Mazdas MZR then:
Valves, springs, bucket lifters and guides, con rods, bearings, rings, water pump and cranks from a Ford unit will fit an NC1, forget most of the rest, it's substandard and/or incompatible.
No versions of the Ford engine in Europe had VVT.
The European Mazda motors always made more power than the Ford ones.
Only a retard cannot read a dipstick and the sump level between min & max is like any other engine - i.e. not an issue. It won't suddenly expire if it's run on the lower level of the dipstick.
An ‘Italian tune up’ will not fix an engine and there is nothing ever wrong with the bores unless a piston or rod has got loose.
Hope this clears a few things up.
An engine rebuild is not £2000, but that does depend on how much of it you destroyed in the first place of course.
They don't suffer from pre 1980s bore wash at all, nor do they have aluminium bores (they have iron liners).
They do not have a worn ring problem and are not exasperating.
All MZR/Duratec units have the same issues no matter what car they are mounted in or where they were built.
As far as interchangeable components go from Fords Duratec to Mazdas MZR then:
Valves, springs, bucket lifters and guides, con rods, bearings, rings, water pump and cranks from a Ford unit will fit an NC1, forget most of the rest, it's substandard and/or incompatible.
No versions of the Ford engine in Europe had VVT.
The European Mazda motors always made more power than the Ford ones.
Only a retard cannot read a dipstick and the sump level between min & max is like any other engine - i.e. not an issue. It won't suddenly expire if it's run on the lower level of the dipstick.
An ‘Italian tune up’ will not fix an engine and there is nothing ever wrong with the bores unless a piston or rod has got loose.
Hope this clears a few things up.
Thanks for the informed information, all the replies from PHers have been invaluable.
All of the information in my first post came from a forum dedicated to the MX5, where I suspect few people have ever worked on an NC engine. The figure of £2k for a rebuild came from more than one source on the afore mentioned website with people saying they had spent more than that paying to have their engine rebuilt. The dedicated MX5 website is just doom and gloom when it comes to the NC engine, so I gave up on hoping to get any useful information there.
The engine in my car, well I've never heard an engine making so much noise and still run, it had been run with low oil for some time (I bought it like that as a non runner). I bought a replacement engine from someone who had done the 2.5 conversion because their old engine had started to use oil, this is the engine I'm rebuilding with new big ends and rings etc. I need to refresh the head and do the stem seals etc.
I'll be removing the old engine in a week or two, there a few bits I need off it like the rocker cover, sump and ancillaries. I've been distracted by my e39 M5 which has just come back from bare metal repaint.
So I'll post an update when I've got it running.
All of the information in my first post came from a forum dedicated to the MX5, where I suspect few people have ever worked on an NC engine. The figure of £2k for a rebuild came from more than one source on the afore mentioned website with people saying they had spent more than that paying to have their engine rebuilt. The dedicated MX5 website is just doom and gloom when it comes to the NC engine, so I gave up on hoping to get any useful information there.
The engine in my car, well I've never heard an engine making so much noise and still run, it had been run with low oil for some time (I bought it like that as a non runner). I bought a replacement engine from someone who had done the 2.5 conversion because their old engine had started to use oil, this is the engine I'm rebuilding with new big ends and rings etc. I need to refresh the head and do the stem seals etc.
I'll be removing the old engine in a week or two, there a few bits I need off it like the rocker cover, sump and ancillaries. I've been distracted by my e39 M5 which has just come back from bare metal repaint.
So I'll post an update when I've got it running.
Some great information from Bertrum, thank you.
Rebuild completed, been running it for a few weeks and no sign of any issues, hasn't used any oil at all. as well as new rings and bearings I refreshed the head, had it refaced, fitted new stem seals etc. Replaced the clutch while I was there as well. Total cost was about 25% of that discussed on the model specific forum, Including the cost of the engine timing tool and the replacement engine for rebuild, but I did supply all the labour myself at no cost and I started off with an engine which had no issues except for worn rings causing increased oil consumption.
Diagnosis of the old engine. One of the big ends has spun and the resulting play resulted in the piston hitting the head, there was very little oil in the engine, about 2 litres and what was left was very thick and burnt.
I did replace the dipstick as some people recommend and I have to agree that it it much easier to read.
Rebuild completed, been running it for a few weeks and no sign of any issues, hasn't used any oil at all. as well as new rings and bearings I refreshed the head, had it refaced, fitted new stem seals etc. Replaced the clutch while I was there as well. Total cost was about 25% of that discussed on the model specific forum, Including the cost of the engine timing tool and the replacement engine for rebuild, but I did supply all the labour myself at no cost and I started off with an engine which had no issues except for worn rings causing increased oil consumption.
Diagnosis of the old engine. One of the big ends has spun and the resulting play resulted in the piston hitting the head, there was very little oil in the engine, about 2 litres and what was left was very thick and burnt.
I did replace the dipstick as some people recommend and I have to agree that it it much easier to read.
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