Newbie - timing belt change

Davros · Postby **Davros** » Sat Mar 04, 2017 3:21 pm

My 2003 NB8B has just clicked over 100,000km so it's time for the timing belt to be done. I'd probably be best described as a bit of a novice when it comes to car mechanicals, that being said I've changed the timing belt, water pump, springs/shocks and the sump gaskets on my BMW 318i e30. I've watched a couple of Youtube videos and the process looks pretty similar.

I've done very little on the MX5 since I've had it, but with the kids almost grown up I've now got a little more time to do things I'm interested in.

My main reason for this post is to get some recommendations as to where to buy the required parts. Should I just go for a kit such as this http://mx5mania.cart.net.au/epages/mx5mania.sf/en_AU/?ObjectPath=/Shops/mx5mania/Products/diykit/SubProducts/diykit-0001&ChangeAction=SelectSubProduct from Mania (with the correct model selectded), or should I be buying from a dealer, or somewhere else?

I'd also like to know if there is anything else i should be doing at the same time, e.g. thermostat and/or other items.

Thanks,
Dave

joshuam · Postby **joshuam** » Sat Mar 04, 2017 4:08 pm

I just did mine in my NB8B over the last couple of weeks (yes, you read that right). Unfortunately you cannot rely on parts from the normal retailers (Autobarn / SCA / Repco).

What I changed:
Timing Belt
Tensioners and Idler (in kit)
Crank seal
Cam seal
VVT seal (***Replaces cam seal on drivers side. NOT included in most kits, and wrong size in almost every ordering manual)
Water Pump (There is an O ring that goes with this that isn't included that I unfortunately did not get to change)
Thermostat (I wasn't planning to change but my old one showed a lot of degradation)
Thermostat gasket
Accessory belts x2 (GATES / Supercheap have these listed INCORRECTLY. Order replacements of what you have).
Rocker cover gasket (Shops do not have one for the NB8B. When you specifically explain what you have, I was sold a NB8A one once and others attempted to several times after. A good visual check is that the central seals are all connected together on NB8A ones, but are seperated 3-1 on the NB8B ones. My car had already been off the road for over a week so I coughed up the $87 for one from Mazda).

All of the above parts are definitely best changed during this service, if you intend on doing them.

Its not hard, but there are a lot of parts that need to come off. It is a time consuming job. Only real issue is undoing the crank bolt. Work out how you are going to do that ahead of time. We made up a bracket to bolt it in place. I wouldn't recommend trying to undo it against the engine / transmission.

The MX5 mania price looks expensive, but after my experience by the time I added up all the extra costs for bits that weren't included it would probably be less than what I paid. If you don't mind waiting a couple of weeks for delivery IL Motorsport are both cheap and reliable (they ship from Germany - can browse website in English though)... I was planning to but I got impatient - kicking myself that I didn't!

JBT · Postby **JBT** » Sat Mar 04, 2017 4:22 pm

It's also worth using a new crank bolt.

Mr Morlock · Postby **Mr Morlock** » Sat Mar 04, 2017 4:44 pm

Read the instructions carefully.- it has to be right- not a tooth out. You can easily buy a crank holding tool from USA at small cost PM me if you want a contact. You can get a quote for the job and see if you reckon its worth your time and inconvenience if you cannot afford to have the car sitting around. All parts are available locally - check Mazda for a bench mark and see also what they supply e.g. belt maker / water pump.The UK source ( Portsmouth) is usually a good source price and del if you want to go down that route.. Buy a good timing belt and water pump which is a known quantity- you can buy cheap but thats not always smart. Rocker cover gasket- when my car was done it had to be sourced from Mazda - same story as Josh. Also for accessory belts again I agree with Josh some listings are just wrong. You just go to Bursons and they will supply the right belts. That latter source can usually also do water pump and timing belt etc.

ralt · Postby **ralt** » Sat Mar 04, 2017 5:12 pm

Hi.
Only use gates belts.

Shadgrind · Postby **Shadgrind** » Sat Mar 04, 2017 6:18 pm

There is a neat trick you could use. Cut the old belt in half along it's length. Slide the half nearest to you off, then with the narrow strip of old belt remaining, slide the new belt on and slide the remaining half of the old belt off the back.
Couldn't find the clip on YouTube from the TVs show Car SOS but I found this....
https://m.youtube.com/watch?v=NzK-ReoVxKM
Just cut the two loops of old belt and you're done.

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Davros · Postby **Davros** » Sat Mar 04, 2017 9:08 pm

Thanks guys,

That gives me enough to research further and hopefully get most, if not all parts in prior to staring.

I'm fortunate enough to have another vehicle to drive while doing this, but i'd still like to minimise the time it's off the road (driving a Pajero or my daughter's '97 Mirage always makes me appreciate the MX5).

Any suggestions for keeping the timing correct, going to TDC on one and making both cam sprockets, a couple of spanners on the cam's and locked togeather, or something like this: http://www.mx5parts.co.uk/camshaft-lock ... -3348.html?

Shadgrind · Postby **Shadgrind** » Sat Mar 04, 2017 9:47 pm

Davros wrote:Thanks guys,

Any suggestions for keeping the timing correct, going to TDC on one and making both cam sprockets, a couple of spanners on the cam's and locked togeather, or something like this: http://www.mx5parts.co.uk/camshaft-lock ... -3348.html?

If you use the slice along it's length method you always have at least half a Cam belt on. So timing will not move. It works I've done it on mine.

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Ned Loh · Postby **Ned Loh** » Sat Mar 04, 2017 10:42 pm

JBT wrote:It's also worth using a new crank bolt.

Is the crank bolt torque to yield?

matti89 · Postby **matti89** » Sun Mar 05, 2017 9:51 am

I done the cam belt on my nb8b a couple months ago. I used the spanner trick for the cams and it worked out ok. It is a time consuming job but fairly easy as it's all easily accessible.
Just remember to set the tension of the belt at the correct point, 10 o clock position on the crank. The video I used for instructions didn't mention this and I had a weird vibration when I put mine back together so I had to pull half of it out again to fix it.

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JBT · Postby **JBT** » Sun Mar 05, 2017 10:43 am

Ned Loh wrote:
JBT wrote:It's also worth using a new crank bolt.

Is the crank bolt torque to yield?

I believe so. If not, it's very close to that and only torque keeps the bolt tight. For the cost of the bolt and it's critical importance, it's not worth reusing it.

smy0003 · Postby **smy0003** » Sun Mar 05, 2017 1:16 pm

Yeah the crank bolt needs massive torque. 150nm from memory?
The bolt itself is extremely stout, I don't think mazda classifies it as a once use part but it makes sense to swap it for the small outlay.

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Mr Morlock · Postby **Mr Morlock** » Sun Mar 05, 2017 2:24 pm

In the end you will have to make a call on what to replace and what not to worry about. As you have an NB P2 I reckon the Mazda work shop manual should be consulted- its written by Mazda - if you check with 93 clubman he is the guru on where to get it on download or check this website for technical info. You can overthink and replace things that dont need replacing.