Sob,sob,sob I'm off my pulley again!
Approximately 18 months after replacing my loose crankshaft pulley with a new one, the symptoms re-occurred. A light vibration at low rev's getting progessively worse over a period of two weeks. Suspecting a re-occurance, last weekend,I stripped all the belts off and checked the pulley bolt for tightness. NO discernable movement in pulley or bolt. Rebuilt the front end and decided to keep an eye on things on a daily basis. Even did an oil and filter change in case it may of been a rogue crankshaft bearing. Yesterday in the space of 5 miles vibrations/knock got worse. Suspecting bearings I started the stripdown this morning starting with the belts. And s**t the crankshaft pulley was loose! ( BUT I thread locked the last one in ! Degreased all surfaces and applied copious amounts of aerospace threadlock )
There's about 1cm of the bolt sheared deep in the crankshaft and the woodrift key turned on the crankshaft face damaging the key slot and gouging a wide area out of the pulley. Took some time to eventually draw it off. Virtually no key left.
SO! My dilema is what to do !
I believe my options are
(a) MIG weld replacement material, in situ, on the crankshaft slot and dress for a new key. Buy a new pulley and cut a new bolt to a shorter length. Lock up tight and cross my fingers.
(b) Strip out the crankshaft, MIG weld repacement material and dress for a new key. Cut a new thread for a replacement oversize bolt( don't think this could be done without removing the crankshaft ?). Replace pulley and cross my fingers.
(c) Replace crankshaft and pulley.
(d) Replace engine due to costs of above.
Selling it is NOT an option!
I suspect any option is going to be expensive.
Any ideas would be appreciated.
Any concept of costs would be appreciated.
I refuse to let it spoil my christmas !!
On that note:- A Very Happy and Peaceful Christmas to all who use and maintain this site.


- (#6540) stephen judge, 22 Dec 02

Never mind what you're going to do about it, why did it happen? Was there a degree of slack in the key or shaft after the last incident? What torque did you tighten to? Did the addition of Locktite affect the torque reading to the point that the bolt was grossly over- or - undertightened...

Any chance of getting a metallurgist to look at the bolt?

Anyway. I'd try to get the last of the bolt out. It's not too far in, and only the threadlock should be holding it. A bit of heat should sort the threadlock, and drilling for an easyout might be possible. If not, how much thread is useable in the crank? If it's approaching 2x the diameter of the bolt, you should be OK... Just cut the bolt a mill shorter to allow for stretch.
Keyway isn't critical, as it's not used for timing, other than for the TDC mark. It's only needed for drive.

As the engine is looking at scrap status in this condition, perhaps an option is to fit a new timing belt, drive the pulley on (after cleaning faces as much as possible and fitting a key), and run a bead of weld, securing it's frontal ID to the nose of the crank. It could be ground off in future, but that would be (hopefully) a timing belt lifetime away...

So, your option (a) is closest to what I'd do, but the welding might be difficult- hard to get enough heat into such a big lump to ensure penetration, chance of damaging oil seals, etc.

Oh, and Merry Christmas :-)

- (#6541) David Miller, 23 Dec 02

Sorry to heasr about this annoying repeat of an irritating fault Stephen. You mention that there is 1cm of bolt still in the crankshaft. Is this from a previous repair or, did it happen on your latest strip down? If it has been buried in the crankshaft for some time, perhaps any torquing of a new bolt has given a false impression, ie, butting up to the broken piece of bolt and still allowing the pulley/key to have some float. As usual, David's advice is very sound and helpful and, in my opinion, ie the welding etc, a bit drastic but, neccessary in this case.

- (#6542) John Davis, 23 Dec 02

Thanks, you guys, for you replys !
Got, my brother ( my mechanic ) to have a look at it. His opinion is pretty much in agreement with David.
Fill the key area of the shaft with temporary filler and MIG the damaged area then dress to fit.
Drill and tap a new thread with the shaft in place. I suspect I may need to remove the radiator to get best access. (The broken bolt is from the last replacement-JD. There is just about x2 diameter length available - DM.)
Then replace with a new pulley and key.
He also suggested welding the pulley against the shaft to ensure it won't happen again. I think this option will depend on how successful the above activities are.
Last time the bolt was just run up as dam tight as I could get it. Torque settings would be good if anyone could supply them ?
Timing belt was only replaced 5,000 miles ( 18 months ago )so I suspect we won't do it again.
Any UK mainland visitors know of a good source of a 3V crankshaft pulley ( + option of a 4th bolt on for steering pump )for a 2CT engine would be appreciated. From memory Toyota charge £160+.
As usual I will keep you posted.
Any further help is always appreciated.
- (#6543) Stephen judge, 23 Dec 02

Stephen,
The torque figures for the crankshaft pulley bolt are
1000 KG-CM (72 ft-1b, 98 N.m).
Another possible way to overcome the problem which you might like to consider. If you "dress" the damaged keyway in the crankshaft, and the keyway in the old pulley,(You could get a local machine shop to fill the ruined keyway, in the pulley, with brazing and you could then cut a new, fairly rough keyway) then press the pulley home (with a rough key in the ruined keyways)are you able to then drill and tap a hole, diametrically opposite to the keyway and along the axis of the crankshaft, with this hole "straddling" the bore of the pulley and the outside diameter of the crankshaft? This would then give you a "round", tapped key, to lock the pulley onto the shaft, the "key" being, say, a high tensile socket headed screw. The pulley securing plate, ie, which pulls the pulley onto the shaft when the securing bolt is tightened, would have to be modified to take the head of the tapped key/bolt but, this would be an opportunity to make up a "tabbed" locking washer, ie, secured by this tapped key/bolt and it's tab folded against a flat on the crankshaft pulley bolt. The different degrees of hardness between the cast pulley and the high grade steel crankshaft, might throw up some problem with drill "wander" but, this can be overcome by some simple jig/guide device and stepping the drills from small to final size, and, also, ensuring that they are sharp. Also, though crankshaft balance should not be affected without it, a key, made up to roughly fit and be inserted into the damaged keyways, would counterbalance the weight of the new key/bolt head, diametrically opposite it. This rough key, if made a "force fit" would give some extra security and would be kept in place by the pulley securing plate. Drilling and "Easy-outing" that piece of broken bolt, would be a bonus, but, if you had to fit a new, shortened securing bolt, at least it would have the security of the tab washer to ensure, hopefully, that it does not move and, could easily be inspected at regular intervals.

- (#6544) John Davis, 23 Dec 02

If the original pulley will go on, and you can get some type of key there (John's bolt into the side of the crank nose sounds good...) I'd be tempted to just build'er up and hope for the best!

torque setting is 72ft/lb

- (#6545) david miller, 24 Dec 02

John
Thanks for your idea.
The old pulley does still fit.
Sounds like a brilliant low cost alternative to a new pulley.
Only thing I would be concerned about, is has the pulley bore been worn oversize. The damage to the bore is localised along its length ! But there is some evidence of wear on the plastic timing cover. Could this be caused from a wobbly pulley or would the bore need to have worn to allow this ? I suppose it depends on how close to the pulley centre it is ! It's hard to know !
Anyway I'll seriously consider it.
Many thanks - a problem shared is a problem halved.
Any other ideas welcome.

- (#6546) stephen judge, 24 Dec 02

Stephen. I am wondering if your pulley, because of the piece of bolt still in the tapped hole, has had a bit of end float because the new bolt was not fully home. However, the pulley cannot move too far inwards because, if I recall, there is a shoulder where a protective plate is held against the lower timing sprocket and which acts as a belt guide. I think that the wear which is evident on the plastic cover is just normal wear due to the plastic flexing. My view is that there should not be any wear which would increase the pulley bore diameter because the pulley and the crankshaft have always turned as one. I should think that the localised wear, along the length of the pulley bore, has been brought about by some "rocking" due to the securing bolt unwinding and, hopefully, this can be ignored if, and when, the pulley is again secured to the crankshaft.

- (#6547) John Davis, 24 Dec 02

Many thanks to all who have helped me with replies.
I have now a replacement pulley, bolt and woodrift key from Plaza Parts via Exchange and Mart mag.
I have a 14X1.5 tap, boss and range of drills, all ready to start.
I have noticed however that the replacement pulley when fitted to the crankshaft ( the pulley shows no wear ) has a little vertical play. I have'nt yet been able to bolt it up tight as I have to drill and tap the crankshaft.
My Question is - Is this supposed to be an interference fit or a tapered fit ?
On reflection, it seems like there is the potential for a heck of a lot of tension on the pulley arising from 4 belts that can be drawn up tight by tensioning bolts. Are there torque values for the alternater and air con pulley tensionner bolts?
I wonder could I have overtightened these the last time and ccreated an excessive load on the Crankshaft pulley bolt, causing it to snap.
I also notice a bit of float on the new bolt which decreases the further it is screwed into the crankshaft. Is this normal ?

- (#6659) stephen judge, 2 Jan 03

Belt tension is set by deflection of the belt at an applied load. I'd need to look up the manual (do you have a RM025E?), but it's something like 10mm/ 10Kg. I tend to set the belts on mine so they "just" don't slip under load.
Play in the bolt thread is normal, play in the pulley isnt. It's not an interference fit, more of a tight sliding fit (parallel). I find that on mine and the odd other one I've worked on, the pulley would slide on about the first half, then needing the bolt to pull it. The manual refers to an SST to drive it on with a mallet, IIRC.
That play might be your problem, the pulley could be free to move under the bolt head, wearing and slackening. Do the last pulley and bolt show ant wear where they contact?
So I'd be thinking about cleaning both surfaces really well, and doing the final fit of the pulley with either locktite or Araldite to take up that play.

Are you going to try drilling the sheared bolt end for an extractor before drilling and retapping?

- (#6660) david miller, 3 Jan 03

The replacement pulley goes "home" without any interference from the crankshaft! The play I recon to be about 2-5 thou - just enough to feel it. I've drilled out the broken bolt remains - about 2-3 threads with progressively bigger drill sizes until I was close to the hole diameter and used a tap to cut/clean new threads. I've threadlocked the bolt in and applied copious amounts around the crankshaft and key. I added a 1mm washer just in case I had'nt cut deep enough. But all my measurements suggested I have. I'm trying to allow for expansion / stretch of the bolt.
This remedy suggests that the key and bolt will have to accomodate the torsion from the rotation of the crankshaft so as a best guess I have over-torqued the bolt about 20%.
Any advice as always is appreciated.

- (#6661) stephen judge, 3 Jan 03