Bolts on crankshaft pulley missing?

[bingbong1]

Hi guys, somehow only just noticed that the 4 smaller bolts on my crankshaft pulley are completely missing. I’ve seen a couple of photos of pulleys without them, but the majority with them. Wondering if this is ok or need to buy them ASAP. Thanks.

[VladD]

For the cost I'd get some bolts in there.

[wildoliver]

I'm amazed your front pulley hasn't fallen off.

I'd get 4 in there asap if I were you. M6 approx 10-15mm long.

The centre bolt only holds the cambelt pulley and the deflection plate on. The outer section is held on with those 4 bolts but some genius has changed your cambelt at a guess, not been able to separate the pulley on removing the bolts (which isn't hard just gently tap it out from the centre) and then thought they aren't needed. Hopefully they haven't just sheared all 4 off in there. The only thing holding your outer pulley on is that bit of rust on the centre bore of the outer pulley to the deflection plate and some hopes and dreams. Best hope the rust doesn't give way.

[bingbong1]

wildoliver said:

I'm amazed your front pulley hasn't fallen off.

I'd get 4 in there asap if I were you. M6 approx 10-15mm long.

The centre bolt only holds the cambelt pulley and the deflection plate on. The outer section is held on with those 4 bolts but some genius has changed your cambelt at a guess, not been able to separate the pulley on removing the bolts (which isn't hard just gently tap it out from the centre) and then thought they aren't needed. Hopefully they haven't just sheared all 4 off in there. The only thing holding your outer pulley on is that bit of rust on the centre bore of the outer pulley to the deflection plate and some hopes and dreams. Best hope the rust doesn't give way.

Holy moly thank you, I'm new to miatas (and cars in general tbh) and after looking at an exploded diagram of the pulley assembly that makes sense. Will get those bolts in, I'll try to find some 10.9 M6 x 12 or something, unless OEM is preferable?

On another note, I'm assuming there's no way to tell if they've replaced the cambelt and waterpump without tearing it apart and looking?

Thanks

[TVRees]

bingbong1 said:

On another note, I'm assuming there's no way to tell if they've replaced the cambelt and waterpump without tearing it apart and looking?

Even if you look, it will not be easy to tell exactly when the belt was replaced.
Could you ask the previous owner for some information maybe?

[bingbong1]

TVRees said:

Even if you look, it will not be easy to tell exactly when the belt was replaced.
Could you ask the previous owner for some information maybe?

I did send him a message about it and he said he didn't replace the cambelt or remove the pulley under his ownership. He owned the car a few years but did barely any miles, so I tried to contact the previous previous owner but no response yet. I should probably give it another go tomorrow to see if I can get a hold of them; there's a few...questionable things they've done lol.

[wildoliver]

By the time you've checked the cambelt you may as well change it. It's not a hard job. Some guy wrote this book https://www.amazon.co.uk/Mazda-MX-5-Miata-Mk1-Enth... which might possibly help with this and some other jobs (shameless plug I know).

That said there are 2 schools of thought on mx5 cambelts. It's a safe engine so if the belt snaps it doesn't damage the internals, just stick a new belt on and go. So A. Don't worry about it. Or B. Plan ahead and change at a circa 60k / 5 year schedule.

I suspect the question is how inconvenient the belt snapping at 3am on the m1 in the pouring rain would be to you.

All I will say is if you do the belt, do change the idler and tensioner and the water pump all at the same time. Full kits are available for very little cost and it's a fairly pleasant job to do on a weekend. Worth considering changing the radiator at the same time if it looks grotty as they aren't expensive either, and you will be dropping all the coolant anyway.

[TVRees]

wildoliver said:

....
All I will say is if you do the belt, do change the idler and tensioner and the water pump all at the same time. Full kits are available for very little cost and it's a fairly pleasant job to do on a weekend.

Worth considering changing the radiator at the same time if it looks grotty as they aren't expensive either, and you will be dropping all the coolant anyway.

I changed belt, pump, idler, etc. without removing the radiator. It was not a problem at all and there was ample space.

[bingbong1]

wildoliver said:

By the time you've checked the cambelt you may as well change it. It's not a hard job. Some guy wrote this book https://www.amazon.co.uk/Mazda-MX-5-Miata-Mk1-Enth... which might possibly help with this and some other jobs (shameless plug I know).

That said there are 2 schools of thought on mx5 cambelts. It's a safe engine so if the belt snaps it doesn't damage the internals, just stick a new belt on and go. So A. Don't worry about it. Or B. Plan ahead and change at a circa 60k / 5 year schedule.

I suspect the question is how inconvenient the belt snapping at 3am on the m1 in the pouring rain would be to you.

All I will say is if you do the belt, do change the idler and tensioner and the water pump all at the same time. Full kits are available for very little cost and it's a fairly pleasant job to do on a weekend. Worth considering changing the radiator at the same time if it looks grotty as they aren't expensive either, and you will be dropping all the coolant anyway.

Yeah you’re right I probably should give it a crack. 3am breakdown on the m1 in the rain isn’t exactly my idea of fun lmao.

[wildoliver]

TVRees said:

wildoliver said:

....
All I will say is if you do the belt, do change the idler and tensioner and the water pump all at the same time. Full kits are available for very little cost and it's a fairly pleasant job to do on a weekend.

Worth considering changing the radiator at the same time if it looks grotty as they aren't expensive either, and you will be dropping all the coolant anyway.

I changed belt, pump, idler, etc. without removing the radiator. It was not a problem at all and there was ample space.

There are many jobs you can do the hard way, but as it takes all of about 5 mins to remove an mx5 rad (mk2 is even quicker) allowing you to check the state of the hoses and rad, and you are draining the coolant anyway and want as much as possible out of the engine to fit the new water pump there is no sensible reason to work around the rad, risking damaging it with tools and making setting the timing back up a little bit harder. I do them on a ramp making my life easier still but I still take the rad off and the ar bar. Give yourself access to jobs, the amount of jobs that are made easier and you save tons of time for the sake of 5 mins of dismantling I lose count of.

Op it's worth considering at least changing the cam and crank seals, they aren't expensive or hard to fit. You will also need some sealant for the corners of the cam cover gasket where they meet the cam caps and do use a genuine cam cover seal, the aftermarket ones are terrible for leaking.

[bingbong1]

wildoliver said:

There are many jobs you can do the hard way, but as it takes all of about 5 mins to remove an mx5 rad (mk2 is even quicker) allowing you to check the state of the hoses and rad, and you are draining the coolant anyway and want as much as possible out of the engine to fit the new water pump there is no sensible reason to work around the rad, risking damaging it with tools and making setting the timing back up a little bit harder. I do them on a ramp making my life easier still but I still take the rad off and the ar bar. Give yourself access to jobs, the amount of jobs that are made easier and you save tons of time for the sake of 5 mins of dismantling I lose count of.

Op it's worth considering at least changing the cam and crank seals, they aren't expensive or hard to fit. You will also need some sealant for the corners of the cam cover gasket where they meet the cam caps and do use a genuine cam cover seal, the aftermarket ones are terrible for leaking.

Thanks. I’d probably order one of the kits that includes the belt, pump, pulleys etc and then also the seals to do it all at the same time.

[TVRees]

wildoliver said:

There are many jobs you can do the hard way .......

As mentioned, it was not a problem at all and there was ample ( = more than enough ! ) space.

However, having a car lift may have helped to make this easier than using ramps.

As you wrote, if it is just a short extra job then why not.