Hi all,
after visiting the DYNO today and my early 1.6 eunos, 1990 only ran 90bhp(at the flywheel) i decided to have a look at the forum, regarding loss of power, and noticed the LWSC problem.
I had a look at mine and I could see that the pulley has a wobble whilst the car is idling, the pulley is the short nose pulley.
I dred to think that it is this problem as i’ve only just bought the car and im already loving it.
My chassis no’s are NA6CE 108659.
Can anybody suggest what I should do, I cannot afford to put a new engine in but I do not want to spend £600 trying to fix a possibly broken engine.
Many thanks
Alex.A
Sorry to hear of the potential problem, but where abouts are you situated?
In Kent, South east-England
Get the car over to this guy, he comes well recommended----------------
Ok, I will contact him,
I spoke to one of my friends and he said the pulley can be re-balenced, or an aftermarket one fitted, however I looked and all I can find are crank pulleys for the later 1.8 94> versions. Can you suggest any sites where I can get a new pulley from?
If the pulley is replaced, what else should I replace, in order to ensure the engine runs sweet?
I just rang that guy, mark is his name.
He told me that it is a new engine job, and will cost £800 supplied and fitted. The replacement engine will be a low milage mk2 1.6 115bhp version. The guy said it is the crank that is unbalanced and not the pulley? which causes the engine to fail.
Does this seem right?
I’ve only read this to discover what
LWSC means! - I’ll get my coat…
Whatever - I hope you get it sorted! [:)]
Me too. I get the gist but don’t know what the letters stand for.
How many miles has your car done Alex. I’ve also got an early car (fortunatly low milage) and wonder how long I have before things might go pear-shaped. [*-)]
For the curious, “LWSC” stands for “LightWeight Sports Crank”. (I thought the name was intentionally ironic when I first heard it, but apparently not.)
The original version of the MX-5 crankshaft has a weakness in the design - the front nose of the shaft (which the cambelt pulley bolts onto) is too short. So the bearing surface where the pulley grips the shaft is much smaller than ideal. If the bolt isn’t correctly torqued, the pulley can begin to move, and then it’s only held in place by the crank key ( a pin which is only there for alignment; it’s not meant to support any load). In time, the key takes a battering and the keyway (the slot in the crankshaft which it fits into) can become badly worn. That lets the pulley wobble around, which lets the valve and ignition timing vary (hence the first symptom many notice is lack of power, especially at low revs).
The LWSC fault isn’t the inevitable fate of 1989-1991 engines - many are still just fine - but you have to be careful to make sure the crank nose bolt is torqued properly (and probably smart to replace it, if it’s ever removed).
Just to add to Martins excellent description. On the 1.6 there is no need to disturb the bottom pully when the cam belt is changed. This only applies to the 1.6 engines, on the 1.8 the pulley has to come off, and the re tightening rules apply.
My car has done 70K miles or 114,000km It has been well serviced andthe cambelt was done about 8,000 ago. I was thinking to remedy the problem maybe to change the pulley and check timing, of course loctite everything up.
The engine itself doesn’t run horribly bad but I might have caught it before it gets worse?
Does anybody know where I can get a new pulley from?
Alex, the pulley is probably ok, it’s the slot in the crank that wears and the woodruff key gets ground down to nothing in some cases. A really good engineer can cut a new key from a pice of key steel, to fit the worn slot in the crank, and then re fit with the proper loctite.
http://www.mx5oc.co.uk/forum/forums/t/228.aspx
http://www.mx5oc.co.uk/forum/forums/t/226.aspx
Both the above posts are required reading[;)]
This is another good place to do some research
http://www.miata.net/garage/garageengine.html
Geoff, your a good man, I will speak to my mechanic to see what he can do, i’ve printed off the posts as its a wee bit technical for me.
I’ll post an update tomorrow, fingers crossed and shoe laces tied(even though ive got velcro)
£800 is quite a lot, but I suppose most of it is labour charges. Have you considered changing the engine yourself?
I bought a recon engine and it cost £350, but a local breakers had 2 recently removed from cars sat around and wanted about £250 IIRC. Changing the engine is actually a very easy job, you just need an engine hoist and basic set of spanners, wrenches etc… and there’s not really anything more complex to do other than just swap the ancilliaries from the old engine to the new one, and perhaps change a few seals and the clutch while it’s in pieces. Most is just common sense and making a note of what you take off, then putting it back on in the reverse order.
I’m sure I read somewhere that the later crank (the 8-slot pulley one) fits into the earlier engine? Perhaps just have the crank and front pulley swapped over?
Am just down the road from you in Chatham,and have done my own key way repair on my car,its not hard to do.If you want a hand to tackle it yourself drop me a pm 
After a long thought I decided to go for the new engine option, and for £800 supplied and fitted. will be from a 2001 1.6 110bhp version. The wobble on the crank was quite bad and the key repair does not put my mind at rest, as the car will be used mainly on the track. I will keep you guys posted,
T minus two weeks before she’s back and £800 lighter.
Good shout. I trust Mark.
Hi Just to update you all,
I got mt car back from Mark and the cars goes like train! Its so quick now. New engine from 2001 mk2, new clutch kit, cambelt, full service inc gearbox and diff fluids. Cost £940 all in. My crank key was worn by about 7mm, or two slots in the timing belt. Mark also advanced the timing by 14 deg.
Very Happy camper now!
Cheers
Alex
Good result Alex, worth the time and money in the end