MX5 1.6 (mk 2.5) cam belt change
Discussion
Hi all,
I have been checking through the service history of my girlfriends mx5 and it turns out the timing belt is due to be changed.
I am thinking about a diy effort on this.
I have looked at a few threads and it sounds like the engine is a non interference type and thus good to do my first cam belt change on!
Could anyone point me in the direction of an on line guide that I could follow?
Thanks for any info.
I have been checking through the service history of my girlfriends mx5 and it turns out the timing belt is due to be changed.
I am thinking about a diy effort on this.
I have looked at a few threads and it sounds like the engine is a non interference type and thus good to do my first cam belt change on!
Could anyone point me in the direction of an on line guide that I could follow?
Thanks for any info.
The Rod Grainger manual is well worth buying - there will no doubt be some slight changed for a Mk2 but on the whole its the same engine.
Buy it its on offer at amazon currently aswell I think. It really is very good. Worth its weight in gold IMO.
As for DIY - yes you should do it. I did mine for the first time last year, following the book - take your time, make sure you have the right tools.
Also - watch these three videos - http://mx5unleashed.com/tech/timing-belt-mx5.html
the method he uses for setting the cam-timing is so easy.
I've also just re-done this job yesterday - a tensioner bearing had failed on mine. The 2nd time round it was a piece of piss.
My hints -
- Buy the camshaft end seal, crankshaft oil seals, CAS o-ring, and a new waterpump. Mainly because you'll be really mad if these start leaking a month after you've had it all apart.
- Buy two big adjustable wrenches - you can use these to wiggle the camshafts and then zip tie them together - and 'lock' the timing. You will also use these to hold the cams while you undo the pulley off the end to change said oil seal.
- You will need some loctite.
- You WILL need a big 1/2" drive breaker bar and a strong 21mm short socket (6point).
- You need a tippex pen/brush. Use this to mark the pulley timing marks, and the marks on the cover plate.
- Also clean and mark the ignition timing marks (TDC, 10deg before TDC, etc) moulded onto the lower plastic cover. And mark the timing notch on the pulley too.
- You will need to reset the ignition timing and idle afterwards - you will need a timing strobe. This is when you realise that putting all those white marks on makes this part 1million times easier.
- You need some silicone sealant for the cam-cover
- Its tonnes easier if you remove the radiator first, give you more room. So if you havent changed it recently, good chance to fill up with fresh coolant.
- You need to undo the plugs to be able to turn the engine over.
- BEFORE taking the belt off, spin the engine round at least 8 times and observe how the timing marks on the pulleys line up every 2 rotations.
- Then do this after fitting the new belt - its then very, very obvious if your a tooth out on your belt.
Go steady and methodically - its a bit scary at first but actually its all pretty straightforward, jsut nuts and bolts - and the book, plus those videos, plus the guides on m.net make it all understandable.
And the best bit is - if you do manage to do it wrong, it wont smash your engine to bits. So no worries.
ETA - just thought that the Mk2.5 might have a Crankshaft position sensor rather than a CAS - so some of what i jsut said might be irrelevant.
Buy it its on offer at amazon currently aswell I think. It really is very good. Worth its weight in gold IMO.
As for DIY - yes you should do it. I did mine for the first time last year, following the book - take your time, make sure you have the right tools.
Also - watch these three videos - http://mx5unleashed.com/tech/timing-belt-mx5.html
the method he uses for setting the cam-timing is so easy.
I've also just re-done this job yesterday - a tensioner bearing had failed on mine. The 2nd time round it was a piece of piss.
My hints -
- Buy the camshaft end seal, crankshaft oil seals, CAS o-ring, and a new waterpump. Mainly because you'll be really mad if these start leaking a month after you've had it all apart.
- Buy two big adjustable wrenches - you can use these to wiggle the camshafts and then zip tie them together - and 'lock' the timing. You will also use these to hold the cams while you undo the pulley off the end to change said oil seal.
- You will need some loctite.
- You WILL need a big 1/2" drive breaker bar and a strong 21mm short socket (6point).
- You need a tippex pen/brush. Use this to mark the pulley timing marks, and the marks on the cover plate.
- Also clean and mark the ignition timing marks (TDC, 10deg before TDC, etc) moulded onto the lower plastic cover. And mark the timing notch on the pulley too.
- You will need to reset the ignition timing and idle afterwards - you will need a timing strobe. This is when you realise that putting all those white marks on makes this part 1million times easier.
- You need some silicone sealant for the cam-cover
- Its tonnes easier if you remove the radiator first, give you more room. So if you havent changed it recently, good chance to fill up with fresh coolant.
- You need to undo the plugs to be able to turn the engine over.
- BEFORE taking the belt off, spin the engine round at least 8 times and observe how the timing marks on the pulleys line up every 2 rotations.
- Then do this after fitting the new belt - its then very, very obvious if your a tooth out on your belt.
Go steady and methodically - its a bit scary at first but actually its all pretty straightforward, jsut nuts and bolts - and the book, plus those videos, plus the guides on m.net make it all understandable.
And the best bit is - if you do manage to do it wrong, it wont smash your engine to bits. So no worries.
ETA - just thought that the Mk2.5 might have a Crankshaft position sensor rather than a CAS - so some of what i jsut said might be irrelevant.
Edited by snotrag on Monday 19th April 11:00
snotrag said:
lots of very useful but awfully technical sounding things
Sounds like a great step-by-step explanation, but I think you've just scared me from doing mine, all this talk of setting timing sounds very technical. And the loctite, is that to fix all the parts that get broken during the process 
OP - didnt mean it to sound scary!
I actually looked it up and it seems that the bit regarding ignition timing is null as the later engines use a (not adjustable) crank angle sensor.
It really is not hard -
Drain the coolant
Unbolt lots of stuff (nothing that is likely to be seized either).
Change the seals (picking the old ones out, pressing new ones in)
Bolt in Waterpump
Fit timing belt (only trickt bit, but explained well in the books/videos and far from 'difficult'.
Bolt it all back together.
Easy.
I actually looked it up and it seems that the bit regarding ignition timing is null as the later engines use a (not adjustable) crank angle sensor.
It really is not hard -
Drain the coolant
Unbolt lots of stuff (nothing that is likely to be seized either).
Change the seals (picking the old ones out, pressing new ones in)
Bolt in Waterpump
Fit timing belt (only trickt bit, but explained well in the books/videos and far from 'difficult'.
Bolt it all back together.
Easy.
teabagger said:
I have decided to "man up" and definately DIY it.
Good for you! 
I've not had the pleasure of taking the head off my motor (yet) but I gather one invaluable piece of advice when doing so is to put an old towel or similar over the exposed head to prevent the embarrassement of dropping tools/nuts/bolts into the engine
Tip for you - Split the old cambelt along its length while its still in place and remove half of it, then slide the new cambelt upto it making sure they are both lined up the same, then push the still in situ half of the old belt off the back, cut in half and pull it out. That way you have never had a point where the engine hasnt had a cambelt on.
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