mx5cartalk.com

Car stats: 1990 NA mx5/roadster import with a later model 1.6L engine (as it has 8 slots)

I am in the process of doing the timing belt, water pump, cam seals, crank shaft seal and CAS O ring service.

Now i am stuck at the part of removing the crank shaft bolt!

- I have tried a little WD40 (there is no exposed thread and the threaded section of the bolt is not very accessible so i don't think WD40 is going to do much)
- I have tried using a cheater/breaker bar to no avail so far
- I have tried using a hammer on the tools to no avail so far

I have read about people bump starting to crack the bolt loose, but am very hesitant to do this.

How did you remove the bolt and/or do you have any advise or suggestions.

PS. If anyone in Southwest brisbane is willing to lend me a torque wrench that covers 116 - 123 foot pounds (~162Nm) for 30mins i would be grateful. I bought a torque wrench without realising that my car had the bigger nose crankshaft and hence a higher torque setting (my torque wrench only goes to 150Nm).

Cheers,
Emil

You have pm.

Terry

About 15mins after my post I managed to get it free (I decided to try one last time)! At first I used various 'breaker/extension bars' but ended up cracking the 21mm socked (in multiple places)! In other attemps trying to use extension bars i ended up bending some pretty solid poles as well! IN the end I got it off using another 21mm socket and a keyboard stand as an extender. Im not sure if it helped but previous to this i hit the bolt head hard multiple times with a hammer to try and 'loosen' it a bit. I was going to try an impact wrench but there wasnt enough space for that and a hammer.

Thanks Tbro for your PM. I will try to get back to you asap (gotta work some things out).

Cheers,
Emil

if only all the short nose crank bolts were this tight!

On my NA8 motor the bolt came undone OK initially and unscrewed about 2 turns before locking solid. Nothing could move it after that. I think pulley wobbling and vibration had mashed the inner threads. I split 2 sockets, bent a few bars and eventually snapped the bolt.

The long nose crank fix on the na6 seems to have been more successful than the crank used from the beginning on the na8, which also seems to have been a problem, though only on a small number of na8s. Doesn't seem to be an issue on the nb8 so far, but note orx626 mentioning in another recent post that there was a revision at some stage, although they're still interchangeable.

I replaced that NA8 crank with an NB8B one. They were identical and so the design is still rubbish. Basically the crank nose is still about 10mm shorter than it needs to be in order to fit the key reliably.

Not sure what the revision comprised, just that there was one of some kind. Interesting though that NB8B crank nose is identical to NA8 - guess we might hear of the problem on NB8s as they get older.

93_Clubman wrote:Not sure what the revision comprised, just that there was one of some kind. Interesting though that NB8B crank nose is identical to NA8 - guess we might hear of the problem on NB8s as they get older.

I have seen failed key ways on two NB8B's in the past 4 weeks (Classic B6 SNC failure mode). One was 190k+ km and the other near 130k. So I expect to see many more as they get older.

Cheers,
Danny

thanks for the info Danny

HUH!!
NA8's can suffer SNC-like failures?! Ah fudge
Would this more-often-than-not be from cars that have missed a proper 100,000km service and had the key installed incorrectly?
Please say yes, cause that puts my baby in the clear.

orx626 wrote:

93_Clubman wrote:Not sure what the revision comprised, just that there was one of some kind. Interesting though that NB8B crank nose is identical to NA8 - guess we might hear of the problem on NB8s as they get older.

I have seen failed key ways on two NB8B's in the past 4 weeks (Classic B6 SNC failure mode). One was 190k+ km and the other near 130k. So I expect to see many more as they get older.

Cheers,
Danny

The 100k service on my car was done very poorly (including installing the pulley crooked!), so at the 200k service the pulley was very difficult to get off.

I feared the key way would be damaged, but it turned out ok fortunately

1red5 wrote:HUH!!
NA8's can suffer SNC-like failures?! Ah fudge
Would this more-often-than-not be from cars that have missed a proper 100,000km service and had the key installed incorrectly?
Please say yes, cause that puts my baby in the clear.

As far as I can tell, ALL keyway failures result from poor workmanship. It's not just a question of putting the key in the right way, it also involves proper cleaning, fitting, loktiting and torquing. I doubt that it even makes a difference whether it's a B6 or a BP motor. Both have serious design flaws to trap the slack mechanic. Just how bad the wormanship was determines how long it lasts after the work. In my case it went 50,000kms before starting to wobble.

Caff and Manga you've hit the nail on the head.

Cheers,
Danny

manga_blue wrote:As far as I can tell, ALL keyway failures result from poor workmanship. It's not just a question of putting the key in the right way, it also involves proper cleaning, fitting, loktiting and torquing. .

Okey dokey, now I can sleep soundly again.
Thanks Phil