I think I've got a short nose crank?
Discussion
I bought an H reg mk1 1.6 on a whim last year because I couldn't justify the Caterham I really wanted. As far as I can tell this has the short nose crank.
What does this mean?
and
I'm not sure when the cambelt was last done, do i need to worry? The car is on about 113k what's the recommended interval?
Thanks for the advice
What does this mean?
and
I'm not sure when the cambelt was last done, do i need to worry? The car is on about 113k what's the recommended interval?
Thanks for the advice
Short nose - four slots in the main bottom pulley.Prone to wear and wobble due to design flaws and or bad maintenance.Repairs are possible but may or may not last.Pulley wobbles often due to design/bad maintenance of main pulley bolt and subsequent keyway wear.End result is degrading performance and ultimately either a new crank or new engine.
Big nose - 8 slots in pulley.Wobble here is more likely due to bad maintenance alone (torque settings usually).Repairs are possible with a greater chance of "getting away with it" than on a short nose.Less chance of wobble than on a short nose and less chance of damage to the crank if you have some wobble.
Cambelt = 60k but is a non-interference so shouldn't bend anything if it breaks.
The often mentioned Long Nose is a service part.
Big nose - 8 slots in pulley.Wobble here is more likely due to bad maintenance alone (torque settings usually).Repairs are possible with a greater chance of "getting away with it" than on a short nose.Less chance of wobble than on a short nose and less chance of damage to the crank if you have some wobble.
Cambelt = 60k but is a non-interference so shouldn't bend anything if it breaks.
The often mentioned Long Nose is a service part.
Easiest way to check is run the engine, pop the hood and take a look at the large bottom pulley at the bottom front of the engine.If it's wobbling about, you may have issues later on.They can have a bit of play afaik due to the rubber harmonic balancer failing aswell, so don't panic too much if there is some slight wobble.
My first car had a pulley that looked like a half fitted wheel cover as it went round so I had it welded on! That's not ideal of course, but the car was cheap so I was never going to invest in a new engine or crank! It still performed well though and to be honest would have still been going just fine now a few years after the repair had it not been smashed up by a van driver.
People do suggest rust being the biggest thing to look out for when looking at an MX5 and hardly ever mention the pulley (the mazda 323 can suffer the same fate) but I will always look for both as I know what may be involved to sort the problem.
There is a lot of information (and misinformation) on the net regarding all the above, but this is a handy link which has some nice images and clearly shows the pulley, keyway (small block of metal type thing) and bolt etc.It's also showing the well known loctite fix.
http://roadsterireland.com/index.php?topic=31.0
My first car had a pulley that looked like a half fitted wheel cover as it went round so I had it welded on! That's not ideal of course, but the car was cheap so I was never going to invest in a new engine or crank! It still performed well though and to be honest would have still been going just fine now a few years after the repair had it not been smashed up by a van driver.
People do suggest rust being the biggest thing to look out for when looking at an MX5 and hardly ever mention the pulley (the mazda 323 can suffer the same fate) but I will always look for both as I know what may be involved to sort the problem.
There is a lot of information (and misinformation) on the net regarding all the above, but this is a handy link which has some nice images and clearly shows the pulley, keyway (small block of metal type thing) and bolt etc.It's also showing the well known loctite fix.
http://roadsterireland.com/index.php?topic=31.0
Edited by Digby on Saturday 19th January 02:33
I tend to find the problem with the crank pulley due to water ingress rather than bad maintenance. When you come to pull off the crank pulley, you generally find a rusty mess which has been the result of a tiny but persistent leak from the water pump gasket, so it's always best to prevent rather than cure. If it's a new car to you, budget for a cam and water pump change.
I find the 'loctite' method a little extreme (660 liquid metal). As above, I think most problems are not from a 'design flaw' and therefore you're trying to fix a problem that's not there. I have never glued the timing gear onto the crank as this will ultimately limit the engine's life as you can't really remove it (there's an oil seal behind it). The wear on the keyway doesn't effect the positioning of the woodruff key, so I tend to clean, polish and de-grease the area and then use some 243 (blue) to set the new key in position and leave to cure. From there you could use a very, very thin smear of 222 (pink) on a section of the crank that the gear fits onto and again allow to cure. You then have a fairly rigid (but breakable) platform to complete the job using 271 (red) on the bolt, and again allowing time to cure (24hrs).
HTH
Phil
I find the 'loctite' method a little extreme (660 liquid metal). As above, I think most problems are not from a 'design flaw' and therefore you're trying to fix a problem that's not there. I have never glued the timing gear onto the crank as this will ultimately limit the engine's life as you can't really remove it (there's an oil seal behind it). The wear on the keyway doesn't effect the positioning of the woodruff key, so I tend to clean, polish and de-grease the area and then use some 243 (blue) to set the new key in position and leave to cure. From there you could use a very, very thin smear of 222 (pink) on a section of the crank that the gear fits onto and again allow to cure. You then have a fairly rigid (but breakable) platform to complete the job using 271 (red) on the bolt, and again allowing time to cure (24hrs).
HTH
Phil
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