Yeah, really annoying. Agree on the alternator belt. Very weird that that’s the only belt that’s so cracked cracked – all the others look fine, in comparison.
Additionally weird that, despite receipts for checking/changing the coolant temperature sensor, there was no thermostat present when I replaced this part. And this was from a supposedly well-regarded main Mazda dealer.
nb the car has 172k kilometres (107k miles) and I’ve noticed the speedo reads very high (you have to do 80mph on the speedo to get to 70mph via gps), so comfortably under that 120k mile water pump lifetime guide.
When my waterpump was failing I had the typical water seeping from behind the crank pulley. In its dying hours, the temperature gauge would go up and down quite erratically with the revs, as every now and again it would kick in to circulate the water and then stop. Just be aware that if this happens, stop straight away or the temperature won’t stop going up and it’ll cook. I never noticed this sound, though…
There’s usually a cutout that stops the compressor engaging if there’s not enough pressure in the aircon system, so yours may need regassing and any leaks fixed.
On our Suzuki if the aircon is turned off for too long (days) the compressor makes a noise similar to that in the video. Turn the aircon on for a few minutes then turn it off again and the noise goes. Saying this, we’ve recently had a fault code come up for low aircon pressure, so it may all be linked to this.
I had assumed there was a gas leak, but didn’t realise low gas would prevent the compressor from engaging. Thanks for this .
It sounds like I need to take the air con belt off and see if the noise goes away. If it does, then I know the car’s safe to drive to a garage for an air con gas refill and leak repair.
Will also plan on buying a new alternator belt for swapping over after taking the old cracked one off to sense check that the alternator isn’t at fault. It looks like only aftermarket belts are available for the 1.6, though, with grooves and some dodgy reviews :
How do you guys recommend adjusting the belts? I’ve read some say " adjust until there is 10 mm deflection when pushed " and others " adjust until you can just twist it 90 degrees " Both seem a bit dependant on the individuals feel and strength ie one man’s push or twist will be different from the next. A young fit gent is going to have a lot more strength in their fingers than an old arthritic bloke like me I’ve even heard " just tighten it up until it stops squealing "
Any suggestions on a more accurate way of doing it?
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Ducati cambelts used to be often adjusted on the 90 degree twist method.
These days its done on hertz, you pluck the belt and check the frequency as with a guitar string, generally around 100 hz on the longest run.
I wonder if Mazda have a herz figure for their alternator belts…
Gates do an app you can use on your phone for measuring the herz frequency of a belt.
Someone on the RX-8 forum did the maths and worked out that they could hold a weight in one hand and match the force required to lift the weight with the tension of the belt in the other hand .
I just do the twist test, coupled with a rough deflection measurement using a ruler, erring on the side of slightly tighter being better.
At work before solid-state-storage we used “tentelometers” to set tape tension across the heads on the various audio and video tape machines, forces in mere grams.
So I was highly amused at the time to see in the FE Victor Vauxhall Service Training Manual the data for setting the belt tensions in pounds; cam-belt 10lbs for 0.3" deflection, and fan belt 80lbs on the tension gauge (a bigger tougher tentelometer).
Mini update… the mechanic’s stethoscope arrived in the post, along with the replacement alternator and power steering/air con belts ordrered from MX-5 parts.
Annoyingly, I’m not going to have time this weekend to take the belts off (to isolate the sound) and replace and re-tension them. However, I did prod around with the stethoscope and – presuming I’m using it correctly – the clacking metallic sound I’m hearing does not appear to be coming from the dysfunctional aircon compressor or the alternator.
Spurred on by the consensus that this isn’t the sound of a failing water pump, I’ve taken the car out for a couple more drives. No issues to report, other than the noise.
Fingers crossed, I’ll get round to sorting it next weekend…
The belt could have been new old stock and the thermostat could have been removed since the Mazda dealer visit. Few Mazda dealer mechanics would have experience of mk1 MX5, they are trained for current models.
Sounds water pumpy to me. Did you say it’s 5 years since it was replaced? If so, it’s worth doing along with the timing belt. They don’t always leak if the bearings go - that’s more if the bushes go. A pump sat in the same coolant for 5 years can also lose it’s vanes through electrolytic corrosion, because one coolant goes off it turns the cooling system into a giant battery, with the vanes being eaten as if they were the sacrificial node in your home cooling system. I’ve just had a pump removed which had NO vanes left on the impeller.
Yeah, although you’d think an NA MX-5 would be common sense to a pro given how straightforward they are to work on vs a newer car .
The old belt stock could explain the cracking for sure. Although the lady I bought the car off never took the car to anyone bar Mazda and she definitely wouldn’t have removed the thermostat herself!
Interesting. According to the service history, the water pump annoyingly wasn’t replaced with the timing belt 5 years (and less than 20k miles) ago. That being said, the engine is holding its operating temperature well, although I’m aware the weather is still pretty cold.
I’ll take the aux belts off first before diving into the waterpump (if the problem persists). If it does need a new waterpump, I guess I should probably do the timing belt and pulleys again too for good measure.
Although, if I’m diving down that route, I’ll start weighing up the pros/cons of putting funds into the OEM 1.6 (which also has a bit of an oil leak at the head) vs swapping the engine out for a 1.8.
Fair point, us amateurs manage to work mk1s out, thanks to the OC when we get stuck. Your cars previous owner has maintained the car regardless of cost, but the dealer had other ideas. I find even local garages are not really interested in old cars, No mx5 specialists near me, so I do most work myself. I have a newish Mazda 6 company car and 2 out of my 3 local Mazda dealers cannot even manage a basic service, I’ve had a missed air filter, grossly exaggerated tyre or brake wear, then when brakes want changing they have no stock, one dealer had no time to check emergency warning lights so I had to ring breakdown service, absolute farce. Luckily the 1 decent dealer are old school customer service.
The heater gets nice and warm now vs before with no thermostat when it wouldn’t heat up at all because the engine was being over-cooled. It’s definitely nowhere near burn you hands hot, though.
When I did a double coolant flush and refill with FL22, the system certainly seemed to have pressure. Quite a bit more coolant (than I was expecting!) came out the radiator cap hole when I burped the system of air.
I changed the aux belts today. When I had the belts off, I tried rotating the pulleys. The water, alternator and power steering pulleys all rotated smoothly and quietly.
There was a slight metallic scraping sound when rotating the AC pulley. I then noticed that there was a load of play with the AC clutch. My RX-8’s AC clutch has no play at all, so I’m presuming this isn’t normal and I have a busted part.
MX-5 parts only seem to have a replacement ac clutch for the 1.8 engine and it’s £180! The alternative options look like taking a punt with eBay parts, a replacement used AC unit (with no guarantee of how long it will last), or an AC delete.
I wouldn’t mind keeping the option of cold air for the summer, but saving a big bill and 17kg of weight also doesn’t sound too bad. And I don’t believe the 1.6 AC unit will work with a 1.8 swap, if/when I get round to that challenge. Aware I’d need to find a shop to drain the refrigerant before I attempted a removal.
I thought I’d found my culprit with the AC clutch, so was surprised to hear that the metallic sound I originally feared could be a dodgy water pump had gone once I tightened my belts and put everything back together again.
Annoyingly, in its place, I seem to have created a vacuum leak as I now have a whistle and a slightly hunting idle . All the intake hoses looked reinstalled correctly, so that will be something else to dig into next weekend.
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I’ve even heard " just tighten it up until it stops squealing "
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. All the intake hoses looked reinstalled correctly, so that will be something else to dig into next weekend.