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Author: Subject: MX5 Cam pulley bolt removal
wet166

posted on 8/12/16 at 07:23 PM Reply With Quote
MX5 Cam pulley bolt removal

I am attempting to replace my cambelt on a 2001 1.8 engine whilst building a kit car. All manuals suggest applying the hand brake and putting it in gear to undo the single pulley bolt. As this is not possible, whilst the engine is in position in the chassis, I cannot stop the engine from turning whilst trying to remove the bolt.
I have tried to bolt a holding bar to the crank whilst undoing the bolt, but it just shears the bolts without releasing ther torque loading

Does anyone here have any suggestions for undoing the crank bolt or how to change the belt without removing the pulley?

[Edited on 10/12/2016 by wet166]

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Slimy38

posted on 8/12/16 at 08:11 PM Reply With Quote
Impact wrench would be my first thought, either air or electric. It'll undo the bolt without putting too much rotation through the crankshaft.

[Edited on 8/12/16 by Slimy38]

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miskit

posted on 8/12/16 at 08:36 PM Reply With Quote
http://www.miata.net/garage/timingbelt.html

Alternatively if you are not going to change the water pump etc. then cut the belt length ways in half, remove front half, slide on the new belt, remove (ie cut) the other half.

Also a certain MX5 kit manufacturer suggests (at your own risk!) a socket, long shaft well braced, and engage the starter motor!

More bracing ideas here http://mevowners.proboards.com/post/59043/thread

[Edited on 8/12/16 by miskit]

[Edited on 8/12/16 by miskit]

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Adamirish

posted on 8/12/16 at 09:45 PM Reply With Quote
I have always put a bolt in one of the bell housing bolt holes then a pry bar between that and the teeth of the flywheel. Never had any issues doing it this way.





MK Indy 1700 Xflow

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chris_smith

posted on 8/12/16 at 09:51 PM Reply With Quote
DIY sos changed one by cutting it as described above this week if you can watch it on catch up





The secret of success is to know something nobody else knows."

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SJ

posted on 9/12/16 at 08:46 AM Reply With Quote
quote:

I have always put a bolt in one of the bell housing bolt holes then a pry bar between that and the teeth of the flywheel. Never had any issues doing it this way.



+1 for this method. I have a V shaped piece of flat bar that fits into flywheel teeth and allows the fly to be locked against a bolt in the bellhousing. That way any bolts like cam or crank pulleys can easily be removed.

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indykid

posted on 9/12/16 at 01:26 PM Reply With Quote
You can only replace the belt on an early short nose crank engine (1.6 up to 92 ish) with the bolt in place, so the belt cutting suggestions are out. Everything else, the bolt has to come out.

What bolts are you using on the brace bar? If they're b&q cheese grade, it's not so much of a surprise, but if you're shearing good quality 12.9 cap screws, you're going to need a BIG impact wrench, or try locking the ring gear on the flywheel if the engine is out and on the floor.

Junkyarddog on MX5nutz used to sell a locking tool that engaged all 4 screws. I believe Jass performance do one too and should probably be for sale on ebay if you can't bring yourself to chain drill one out of some plate.





me? ambivalent? well, yes and no

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luke2152

posted on 9/12/16 at 03:38 PM Reply With Quote
I got a tool off ebay that slots in between the cam wheels and locks them to each other. Simple and effective:

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wet166

posted on 10/12/16 at 07:15 PM Reply With Quote
responses

Many thanks for the ideas. Most have been tried in some form and the splitting of the belt will not work on this engine, as also noted in the replies. The locking tool is an idea that I was not aware of but will look further into to use along side an impact gun, as this is probably the way forward.
This engine has been very problematical with siezed and rusted parts, so it was not unexpected that most of your sensible suggestions would/did not work. Any more will be reviewed and commented on as they come in and I will update on my progress with this problem for likemined builders with similar difficulties.

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wet166

posted on 31/12/16 at 04:18 PM Reply With Quote
Further update

I have tried the impact driver method and this has not moved the bolt at all. The last. non damaging thing to try will be locking the two top drives with a tool similar to that suggested above from MX5 parts before engine strip or replacement, neither of which is prefered or cheap. More to follow when the garage is warm enough to try it out.
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Slimy38

posted on 31/12/16 at 05:18 PM Reply With Quote
quote:
Originally posted by wet166
I have tried the impact driver method and this has not moved the bolt at all. The last. non damaging thing to try will be locking the two top drives with a tool similar to that suggested above from MX5 parts before engine strip or replacement, neither of which is prefered or cheap. More to follow when the garage is warm enough to try it out.


While that locking tool does look quite useful for keeping the correct timing, you won't be able to use it to undo the crankshaft bolt. You'd be applying torque against the rubber teeth of the belt and they'd have no chance.

Or have I misunderstood its use?

Edit: I'm going to hazard a guess that you're referring to the crankshaft locking tool, IE this;

eBay Item

I'd like to hear the results though, it seems like a perfect tool for the job.


[Edited on 31/12/16 by Slimy38]

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wet166

posted on 3/1/17 at 06:33 PM Reply With Quote
Follow up to Slimy38
While that locking tool does look quite useful for keeping the correct timing, you won't be able to use it to undo the crankshaft bolt. You'd be applying torque against the rubber teeth of the belt and they'd have no chance.

Or have I misunderstood its use?

Edit: I'm going to hazard a guess that you're referring to the crankshaft locking tool, IE this;

eBay Item

I'd like to hear the results though, it seems like a perfect tool for the job.


[Edited on 31/12/16 by Slimy38]

I had realised that the torque was against the rubber teeth but was prepared to risk it due to desperation. However the tool suggested by you, and now bought, is another avenue to try using a proper tool instead of my Heath-Robinson bar. Hopefully more purchase on the flywheel bolts will hold it enough to break the torque and rust (or I will need more drilling of sheared bolts).

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rusty nuts

posted on 3/1/17 at 09:04 PM Reply With Quote
If your able to get at the flywheel bolts easily then refit the flywheel and install a bolt into one of the bell housing bolt holes use a large screwdriver/lever/homemade tool into one or more of the flywheel ringear teeth , jam against installed bolt to stop rotation of the crank whilst undoing the crank pulley. Job done . Or use a decent impact wrench.
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tmay1991

posted on 4/1/17 at 06:54 PM Reply With Quote
my advice from owning 3 standard bodied mx5s is heat on the bolt, steel when heated expands 1thou for every 100 degrees its temperature is raised (cant remember if degrees c or f), when a bolt is constrained within a tread it will only expand length ways but will retract in all directions on cooling which will aid in breaking the mechanical grip from rust or threadlock on the bolt treads, it is also recommended to replace the bolt afterwards, little tip on refitting the cam belt there will be 19 belt teeth clear between the tops of the pulleys when the cams are correctly aligned and the I (inlet) and E(exhaust) will be topmost on there respective camshafts.

hope you get it sorted lovely simple engines to work on though when not fighting rust

Tom





please forgive me Im just learning

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wet166

posted on 7/1/17 at 07:28 PM Reply With Quote
Success

After using a make shift bar bolted to the pulley, an impact driver and several other methods to get the bolt out, the tool that Slimy38 suggested was successful. The unlock torque was way over the setting figure that locked it in in the first place and this is what was causing the problem. The final suggestion made in this thread was also suggested by a friend but I was concerned about the oil seals and having to replace that as well. This was slowly turning into a complete strip which I did not want or need, but with the help of Locost this was avoided and provided a good thread for future belt replacements.
The onyy problem now is that I can't torque load the bolt because everything is so well freed up. This can be cured when the build has progressed and the car is back on the floor.

Thanks for all the input and suggestions from the community.

[Edited on 7/1/2017 by wet166]

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tmay1991

posted on 8/1/17 at 01:51 AM Reply With Quote
For the cost of a replacement front oil seal I would replace it, as a matter of course, the front end strip down whilst not difficult is a faff and these engines are known for leaking oil seals front, rear, cams and the rocker gasket, if it's a mk1 engine with the cas on the rear of other inlet or exhaust cam it's worth changing that aswell, mx5 parts or autolink offer quality parts if you can't get them local

Well done with getting it off really can be a t**t on occasion





please forgive me Im just learning

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