A while ago I’d changed a water pump on a Mazda Astina (on the side of the road) but couldn’t get the crank pulley bolt undone in order to change the timing belt at the same time - even using a rattle gun!

The problem was that the car didn’t have the usual hole in the bottom of the gearbox to allow the flywheel to be locked in place to undo the bolt.

I ended up putting it back together with the old timing belt temporarily until I could have another go at it in the workshop.

After trying a much larger rattle gun and various other methods, I made up a steel bar to lock the crank pulley against the chassis, and with a 2 metre extension on a breaker bar I was able to undo it!

The rest of the job was much easier

This car had a whole list of things to do, and is going to be a very nicely set up track car that’s also usable on the road.

The main things added were power steering, some serious chassis braces, and a new ignition system that should work better at high boost levels.

I also removed the air conditioning to save some weight, made up an intake heat shield, installed a larger swaybar, race seat, fixed up the two stage boost controller, and sorted out a few cosmetic items.

This is what the engine bay looks like after painting the cam cover, installing the new ignition system, power steering, and the intake heat shield:

Underneath the car there’s a new swaybar, a diff brace, and this rather massive chassis “butterfly brace”

It bolts on over the original chassis rails, then the “wings” link the two. It looks pretty impressive, and being all stainless steel it won’t rust!

The only issue is that it reduces ground clearance a bit, especially in the middle where the brace has to clear the exhaust.

This car was overheating, mainly due to gradually leaking all its coolant.

The filler cap fitting on top of the engine was leaking where it bolts onto the thermostat housing - which was also missing a bolt, the rubber hose to the overflow tank was blocked, and the pressure cap seemed to be leaking.

I removed the water / air separator, which is prone to leaks - and replaced the filler cap fitting with an earlier model with the overflow outlet. This simplifies the cooling system a bit and is a fairly common modification on these cars.

After also replacing the thermostat and sealing the housing the cooling system was working properly again

This car had suddenly started overheating, and after removing the thermostat and running the engine it was obvious that the coolant was not circulating - which suggested that the water pump wasn’t working.

It’s rare for a water pump to just stop working altogether - and it’s not easy to verify damage without removing various other parts.

On most engines with a timing belt, the water pump is underneath the belt and its covers, so if you’re replacing the water pump it’s also a good idea to do the timing belt if it’s anywhere near a 100,000km interval.

After removing the pump it was obvious why it wasn’t working!

The impeller had broken into several pieces and was not connected to the shaft at all!

Interestingly, this pump had a plastic impeller, whereas the new one is metal.

I was able to retrieve the remaining bits of impeller from inside the engine block by flushing it out with a hose from the other end.

After installing the new pump the engine was happily circulating its coolant - but the radiator needed a good clean out as it was a bit clogged with rust from the engine which had come loose due to the overheating.

This was a good job, because it involved driving around in a convertible on a nice sunny

The other part was swapping the factory springs and shocks for Tein and Bilstein items, which is not too difficult on most cars.

The MX5 was a bit of a pain because the front upper wishbones had to be disconnected from the chassis to allow space to get the strut out, and the springs are very long so normal spring compressors are only just usable. There are also a few little brackets in the way of the other suspension bolts which is annoying!

The end result was that the car sits about 25mm lower, has pretty much the same overall feel, but better handling of road bumps. It should handle better when close to the limit now too.