I bought this car 5 years ago with 4 previous owners and it was 100% unmolested. Over the years I’ve done some mods, rust repairs but nothing major. It consumed a very small amount of oil, and since it’s my 3rd car, lets say it gets driven hard whenever the sun is out and I need a smile on my face.
It needs a new engine or a rebuild and I’m trying to workout the best way forward. It has got low compression, about 170psi on 3 cylinders and 150psi on 1. I need to top it up with oil every 500miles, it goes from Max to middle on the dipstick in that space of time. In the oil I found copper glitter meaning the bearing caps are worn-out and piston rings too.
I’d love a 2.5 but here in the UK is hard to get one and I’ll probably looking at 2k all in if lucky if doing it myself. I just don’t want two faulty engines in my garage.
If I keep the 2.0, I want a supercharger from BBR at some point so it needs good internals.
I can’t really seem to find a late MK3.75 engine.
I have £2k to spend on this fix, what should I do? Rebuild existing? buy a used one? There are a few people on ebay either doing a 2.5L swap for 3k, someone selling a fully reconditioned 2.0 for £1700.(eBay)
Also I really fancy doing a build myself, I’ve fiddled with engines before but never took one apart completely.
Its a hard one, I think the main issue is that you might have the wrong base car, a 1.8 2006 car is starting with more issues than you end goal may allow, eg a powerful track car. (not having ago at 1.8s)
The 1.8 needs a rebuild if its using oil, only way to fix it is to replace the piston rings and drill more oil drains in the pistons. That means new bearings, bolts. Theres nothing to say your bearings will be in spec, you cant just throw std bearings in and hope for the best (well you can, but…)
If the spec is out, then you will have top have the crank ground.
Parts cost for a rebuild if all goes well, about £700 min.
If your car is def solid and has no rust, then yes a 2.5 swap can be done. The 2.5 is ok standard, but needs camshafts to bring it to life. I did a costing about 2 years ago to swap a 2.5 into my 2.0, it was about £2.5k if I did the work. I had most of the parts, but decided to turbo my 2.0 instead as the bang for buck was better.
Just another thumbs-up for Performance Link if you’re anywhere near the Tewkesbury / Cheltenham area. Even if you don’t go for the K24 (I’m guessing it’s quite a bit more than 2K), Alex and Tom have a wealth of knowledge and experience with Mk3s.
So… Its very easy to take these cars to a specialist, and Performance Link have a good rep, the downside is the cost considering these cars aren’t worth that much, lets be honest.
You sound like you want to learn, I would say take your engine apart before making any further decisions. You can learn a lot from this, how things connect and work. Take measurements of what you have and see if it is all in spec. If it is, then you can rebuild it.
Later in my series of turbo videos I do change the manifold to a cast Kraken one. You can go a step further and buy the manifold and down pipe. Thats all the welding other than intake pipes done. I just taped my intake pipes together and took them to a welder. Kraken Manifold and Downpipe for Mazda MX-5 NC
That’s all really good info thank you. I don’t have an engine stand or hoist so will need to buy those too.
Is there anything I can buy to make the internals stronger? I know you can buy forged pistons and crank. But let’s say if I want a max of 250hp, what could I buy to make it more reliable in that power band? Will OEM internals be ok?
I also understand if I do this myself there’s a high risk of things going BANG! and all that money down the drain.
I dont think you will have any issues on standard engine at 250bhp.
Where are you based, normally there are people with engine stands etc near you that will be willing to lend.
Regarding the link, my first warning sign is the all over silver paint job, no internal pictures of work done. I have not dealt with 88mm pistons, but if they are OEM, why are the valve reliefs the wrong size and need machining.
I am in the process of having mine rebuilt by a well reputed guy. Before that I employed a cowboy firm in Chadwell Grays Essex, I did not know this at the time obviously, to recondition it for £2000 ,unfortunately the cowboys took the engine out along with its air conditioning pump ( so that needs fixing too) took apart the engine down to just nuts and bolts and then told me they wanted £5500 for parts and to put back together, I had already paid them £650 deposit! I got the car collected along with 2 huge boxes full of bolts and parts.
If I thought the rebuild would cost more than 2grand to fix I would have got a reconditioned 2.0 engine from MX5 CITY Reconditioned Mazda Mk3/3.5 NC Engine Units | MX5 City
Good luck in your venture.
It’s your third car so i would rebuild the engine. You have some mechanical experience so have the tools mostly?
Once out of the car the strip and rebuild is much easier and more satisfying that anything else on a car as you have space to work. No dirt or rusty nuts. The inside of and engine is a delight compared to all the shite outside it🙂
Don’t bother with bore micrometers, just get the block rebored and the engineer will tell you what oversize piston you need.
Similarly, you can get the crank checked for a fee and see if it needs a re grind.
I used to rebuild Ducati single engines and restore complete bikes. The engine rebuild was always the most enjoyable part of the process
I would look for a cheap 2.0 with rust! They are appearing more frequently now and you could do a compression test on any possible purchase. Swap engines and you will have 2 running cars and can sell the donor.
Thank you all for your inputs, I think I will go down the self rebuild route. Secretly I always wanted to do it. My second option would have been a refurbed one from Mx5city. There are lots of used NC1s about but at the end of the day you will buy another weak engine. Maybe a K24 one day when I make my first million and have all that disposable cash
I disagree with this post. The measuring is the key to a good rebuild. Most modern engines with normal use do not need a rebore of the cylinders. I have rebuild a 120k mile 1.8 NC engine and all the bores were in spec and you could still see some of the original honing. All it needed was a light hone and new piston rings. So for £20 (cost of a bore gauge) and 10mins work I knew it was in spec.
There are loads of videos on Youtube on how to use a bore gauge and read a micrometer.
Take your time, watch videos, ask questions of the right people and you will enjoy the rebuild.
For a different engine I recently had a refurb done for 2k in euro’s. It’s an absolute shitpiece. @sparks in this topic also warned for this, @CompletelyDriven also remarked some suspicious stuff. If you want to cheap out ánd want to experience doing it yourself then the best route is cheaping out on labour - do it yourself Would be a great learning experience. Just take into account that it will cost a lot of time. I can do the same as reputable shops (more or less) but it will take me 20 times more time, 15 times more the second time I do it etc. Also, don’t cheap out on parts when it’s out. I’d try to just put everything new on it, at least the parts that won’t be so easy to change once the engine is rebuilt and refitted.
Perhaps you can research what it would take to use internals (rods, pistons and whatever is different) used in the NC3. It is said that the NC2 and NC3 are less prone to the common oiling problems and shot bearings. Also, in my NC1 engine I have changed the oil dip stick to an NC2/3 dipstick. I found out the min and max level is actually higher on the facelift dipstick even though the blocks are the same. And while you’re add it, add a baffled sump. If you do the above I think you’ll have a majorly upgraded engine in terms of reliability. Go big (in intentions) or go home
Fair criticism from completlydriven and RichardFX. I thought chrome was for mudguards and bumpers! Maybe if the chrome bore doesn’t wear and can be judged just visually you still may not need those big micrometers?
Just trying to save my honour here you understand🙂
I have started to acquire the necessary tools. hopefully picking up an engine crane today.
Question, is there a manual or a pdf I can purchase where it has all the measurement specifications for the duratec? i.e. bearing clearances, piston ring gaps etc. Thank you.
Would be a great learning experience. Just take into account that it will cost a lot of time. I can do the same as reputable shops (more or less) but it will take me 20 times more time, 15 times more the second time I do it etc. Also, don’t cheap out on parts when it’s out. I’d try to just put everything new on it, at least the parts that won’t be so easy to change once the engine is rebuilt and refitted.