Thread: Play in crank pulleys

Dont think there should any slop at all.

Is the slop against the key, or is it loose on the shaft?

Loctite 660 will take care of it if the gap is less than 0.5mm. A badly wallowed keyway can be repaired with Loctite 660 and metal shim,

Cheers Charlie

I can easily push both on by hand and the damper has a little on the key and lose on shaft. The key way has no sign of wear.

I have four TDi300 auto Discoverys that keep me busy with repairs. Not sure of the exact state of your crank keyways, the harmonic balancer or timing cog, but hopefully my experiences (suffering) may help.

The timing cog and the harmonic balancer both mount on the crank nose, and originally have separate keys. My experience with good condition harmonic balancers and the timing cogs has been that they are both an easy slide fit with the keys in place. I would expect slight movement. In general servicing the only annoyances have been the sealing ring behind the timing cog, and the keys moving in their respective slots as I try to put the cog and balancer back on – not mentioning of course the tightening of the crank nose bolt.

One of my vehicles had the the top of the key sheared off by the balancer. The bottom half of the key remained in the keyway in the nose of the crank. The other half of the key was in tiny pieces. I can only guess the pieces acted as a grinding agent, overwidening the bore hole of the balancer, or reaming the bore before it broke. The balancer in this case was obviously too loose to refit. One day I will bore out the balancer and sleeve it back to the right size. Suggest you check the balancer and timing cog bore holes for grinding wear.

The timing cog and its key were still in good condition and engine timing was unaffected.

The crank nose is tough stuff and showed only minor scratches.

The serpentine belt was running erratically and there was lots of noise when the engine turned off. The initial exploration showed the crank nose bolt was obviously loose.

Before the harmonic balancer key sheared in half it had damaged one side of the keyway. The crank rotates clockwise. The momentary resistance of the loose balancer forced the key against the left side of the slot (when looking in to the engine bay from the front of the vehicle). This repeated action resulted in the left side of the slot being hammered from vertical to a slope. A new key would not stand straight, but rather, fall to the left. The right side of the key way was still vertical and sharp and a nice fit to the key. So I had a half good key way.

Leaving the crank in place I decided to widen the keyway in the direction of the damaged side. I purchased a 'dremel' type high speed tool, and an assortment of small carbide slitting saws and grinders all of about 25mm dia or less. It was slow and tedious. I ended up with a keyway straight on both sides, and correct circumference (depth), but too wide for the key. I got some thin mild steel offcut, traced the shape of the key onto it and then proceeded to hand shape and thickness the off-cut to match the extra space in the key way – minus what would normally stick out above the slot.

I got some two pack 'liquid metal'. Acting quickly I smeared a small amount of this against the left side of the keyway, inserted the shaped steel offcut, then inserted the key and left the lot to sit in place overnight. Once cured the off-cut is held in place and the key is removeable. The fit of the key is nearly as good as original. I checked the 'liquid metal' about 20,000kms after the fix and is still in place and still holding the off-cut.

The secret is having the nose bolt properly torqued so the keyway has little or no stress.

I could be wrong, but I am not aware of 'glue' (ie locktite?) being required for items in good condition, ie the keys, the timing cog, the harmonic balancer, washers or the crank nose bolt. I could only imagine 'glue' making servicing more difficult. I've heard some people do 'glue' and they claim to have no problem.

Some have thrown the original keys (half round, woodroffe?) away and instead have ground one continuous rectangle profile slot from the beginning of the crank nose, to the rear, then fitted one long square (quarter inch?) key to serve both the timing cog and the balancer. This is probably a crank out of engine experience.

If you have to grind the timing cog keyway, assuming damage to the left hand side, then shim and glue on the left side, keeping the good right side as a guide to correct alignment of the key to piston top dead centre. Otherwise timing could be affected.

Also check the condition of the rubber bonding between on the harmonic balancer rings.

Originally Posted by workingonit

I could be wrong, but I am not aware of 'glue' (ie locktite?) being required for items in good condition, ie the keys, the timing cog, the harmonic balancer, washers or the crank nose bolt. I could only imagine 'glue' making servicing more difficult. I've heard some people do 'glue' and they claim to have no problem.

Loctite and similar products can be used on any new component - used on the crankshaft pulley from new, they would have prevented the wear you experienced on your engine.

For people new to the product, it is important to get the use-guides from a Loctite agent before you purchase or use the product. It would be easy to use the wrong one, which might make disassembly extremely difficult or conversely fail to do the job,

Cheers Charlie

There should be no wobble and no radial movment on the pullies once fitted with the woodruff keys.

They should slide back and forthe quite easily.

With both in place tighten up the crank nut to 30nm and there should be no axial movement.

I woulsbe using something like 690 to secure the keys in the hole but be bloody careful to get the keys in square and clean up any excess before you go and put the pullies back on, ideally leave the goop to cure before assembly

Via the modern day equivalent to smoke signals fromsome place other than the cave where my hat hangs.