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No - we don't think you're dumb at all.

Whether you pull it apart, or swap it over, if you can read a workshop manual and twirl a spanner yourself you're gonna learn something.

I think rebuilding an engine does require some skills and knowledge. Paying for a rebuild naturally is also not an inexpensive exercise as most will charge anything from about $70-100 per hour. I reckon you re build or replace engines when there is a need to do so. If a vehicle still has good comp over all cylinders and is not burning oil best to leave it. Considerations are ones own skills and equipment and facilities and the time that can be allowed for the car to be off the road. Spending about a $1000 is not hard. A secondhand engine is also in most instances an unknown quantity and someone intending to keep a vehicle for an extended time may opt to repair and renovate. If the subject vehicle has only 110K or so on the clock one may imagine it has plenty of life left.

The short nose problem can also happen to the 1.8s too, did to my 1.8 as well as many other engines that aren't Mazda/Ford.

MH999 wrote:So i just wanted to know the cost to rebuilding the motor over buyin 2nd hand.

This is really hard to tell you as it depends on how much work (machining/engineering costs) is needed on your block & head, how many replacement parts (new aftermarket or OEM) you will be using PLUS the hourly labour costs.

Workshop standard rebuilds can cost anywhere from $3-$4,000 upwards and can climb astronomically high depending on what you end up doing. From memory, I believe that the standard B6 conrods are no longer being sold and so you can only use the BP ones.

Most people just replace their 1.6 B6 with a used 1.8 BP motor ($800 to $1500 depending on condition - get a static compression check or source it through a workshop). Most people also use a conversion kit like this to run the BP in their NA6 -> clicky. Just be aware that for some reason, some cars do not always run fine with the NA6CE computer and BP injectors (see here).

So in summary, if you want to keep the car for a long time then consider it an investment. Otherwise the fastest way to get the car back on the road is a straight swap or swap to the slightly newer 1.8 BP motor.

Hope this was somewhat helpful.
Les @ MX5 Shop

If you can live without the car for a few months (you could do it in 4 days, but that never happens in the real world..) and are happy to get your hands dirty then a DIY rebuild is easy enough - I did it and it hasn't blown up yet...

Yeah, I would go for a self rebuild. I would say on a scale of 1-10 where 1 is never touched a spanner and 10 full accomplished, I am about a 6-7. I have re-built several engines and it is all about taking your time, measurements and not cutting corners. It is not difficult, but is just scary at first because you don't know what kind of job you have done until it is back together and running.

You will of course need to find a local machine shop for some of the work on the head (re-face, possible valve guides), but other than that, you can go it alone. I would also recommend fitting as many new parts as possible (pumps, idle pulleys, etc). It is false economy to save on something like a cam idle pulley to have it destory your new engine.

Quality tools will make a differenct to the job too.

I have built 3 engines (1 for my pug 205 gti rally car) with no formal training and none of them exploded.

Also, you will read loads of conflicting info about build and run in. I don't think there is an agreed methodology.

I personally, use clean oil and a very high quality bush to coat everthing in oil as the engine goes back together (some people us an engine building paste, redline do some I think), I turn the engine over (spanner) before the head goes back on, to prime the oil pump and check that it is working. Once in the car, I start it and run take the car for a short drive immediately, doing several part throttle accelerations followed by slowing under the engine deceleration (apparently helps get a good seal with the honned boars and rings). Once back, check everything over.

I have not been in gearbox yet, but that is to come, because my Na6 box makes nasty noises

Si.

Pages 39-41 of the following book provides a good description of & solution to the short nose crank problem.

http://books.google.com.au/books?id=gSt ... q=&f=false

In the spirit of prevention being worth more than cure, I'd suggest checking yours to try to ensure it doesn't happen, especially if there's no damage already. That way a rebuild might not be required during your ownership.

Experiencing the short nose crank problem isn't a foregone conclusion which can be predicted. For example, it happened to my old '89 NA6 prior to the usual timing belt & water pump at 100k kms service. I'd owned the vehicle since 3k kms & it had always been serviced by Mazda.