Hi I have seen a 1990 Eunos to buy. The car has a squeak when idling it does increse slightly as the speed increases. Is this possibly the water pump or alternator. Are these models prone to failure of these two components? Also I have heard the the earlier cars had a problem with crankshafts..is that true and if so when did mazda upgrade these? (11/99)

Its probably the water pump bearings. Mine has started to squeak a bit at about the same miles (85000 kms), and I know of a couple of others with the same problem, one with a very noisy pump. The pump is cheap; only about £30 from a motorfactors, and since you're too far off 60k miles, you might as well replace the water pump and timing belt. labour is costly though.

From what I have heard; the bearing on the water pump wears before the seal, so there shouldn't be much danger of coolant loss (indeed the afore mentioned car with a very noisy water pump, is still going strong on the same pump after a hard summer) (11/99)
After much poking around I found the Vin no.for the uprated crank in UK. It would appear that the strengthened crankshaft was fitted to cars with UK chassis numbers from 00110630 (final digits) . This is the no at which the recommended torque for the crank pulley bolt is increased.(bigger bolt also? can anyone confirm?) You will need a japanese manual to find the relevant Eunos vin no (are you reading this Jay). If the bolt is bigger you just need to carry the right socket when you look at a car. The bolt can be easily reached on the front of the engine. Although failures have been documented in US has anyone over here actually had one break? (11/99)

I have one. It hasn't broken yet, touch wood, and I have done a belt and seal change. My understanding of the reasons for the crank failures is bodgy maintenance. The cranks don't just up an fail, not onece they are through thefirst half of the bathtub failure probability for the whole engine.

The failures I have seen on the net are due to fatigue and the propagation point has been the woodruff key slot, due to improper replacement of the key and/or failure to use a torque wrench, or use one properly when tightening the bolt. Mazda used quite plain words to describe the phenomenon. Again touch wood, if everything is done in accordance with the book there should be no problems.

Mazda gave the MX5 the light crank to add performance and allow the engine to spin easier and last longer by reducing the internal inertia forces. Ham fisted and inadequate maintainers caused them to replace the crank with the one from the bread and butter sedan.

Well I think that is how the story goes.(11/99)

Early 1.6 cars (and weak front crank pulley/crank the first year, less than 500 of those were shipped to the UK) strengthened crankshaft was fitted to cars with UK chassis numbers from 00110630 (final digits) One sure way to tell if it is the later crankshaft is to try fitting a 21mm socket to the bolt on the end of the crankshaft. If it fits, you have the later crank, if the socket is way too large for the bolt, you have the light weight sport crank.

If you'd like, verify the stronger crankshaft and larger bolt are fitted by measuring the bolt shoulder diameter to be 1.455 inches. If your Miata is a 1990 or 1991 with VIN 209446 or less, you have a crankshaft with a smaller diameter nose. The pulley bolt shoulder diameter is 1.128 inches.

There is an intermediate fix in the form of a longer nosed crankshaft with the same small diameter. .. clip of various bits of info. and the chassis numbers are not 100% accurate ... as the socket bit is not.. (11/99)

Wrong. Both bolts require a 21 mm socket.

The socket bit is 100% inaccurate. Otherwise good info.(11/99)
If anyone's wondering about a lightweight crank failing on a stock 1600, there's a fair few of us going around with the extra stress of an s/c on it with no problems as yet... I'd agree with the bit recently posted about failures being due to incorrect maintenance rather than general weak design. I asked the (ex) service manager at Coventry Mazda once whether they'd heard of any cranks going, he said they'd heard of perhaps two. (one was someone who killed their engine with a bad supercharger installation) (11/99)
Took my roadster out for a run this morning . Within 10 mins the temp guage was 'off the scale'. I checked the engine bay and i find there is a leak coming from around the pulleys at the front of the engine. the expansion tank shows a fluid level just below full but the rad is bone dry! Anybody know if the prob is with the water pump? If it is, can it be serviced or does it need to be replaced? Is this a job that I can attempt? (bearing in mind all i have is a few spanners etc + limited mechanical knowledge) (10/00)
Sounds like the water pump has sprung a leak. Can't really service them, AFAIK - new ones are £67 from Moss - but check with Mazda - some parts are cheaper. Fitting is much the same as doing the cam belt - you just go on and remove/refit the water pump. If you don't change the cam belt, mark it so you can keep the same direction of rotation. (10/00)