Crankshaft pulley bolt coming loose twice after swap

[flyingdutchie]

Thought I would give this question a go overhere. Actually I have a Marcos 3.9 serpentine. Ordered a 4.6 litre long block at V8 Development and the bolt/pulley came loose twice. The same pulley is mounted on the 4.6. V8 Development supplied this pulley loose with the engine. I re-used the bolt an put 270Nm torque on the bolt. In both cases the pulley came loose quite quickly. Ca. 500km's. The shaft on the cranshaft has no damages.

On the website of RPI I saw that they supplied spacers for the pulley bolt in some cases, but it was not clear to me when such a spacer has to be used. What could have gone wrong? Mounting it back again wil not bring anything. There must be a cause....

[Pupp]

Immediate thought is that perhaps there is a balance issue with the pulley but I think V8D stuff is neautral balanced component by component so shouldn't be an issue - I'd give Ray a call and query it

[Steve_D]

You mention spacers.
There is a very thick washer (approx 8mm thick) normally used with these bolts...I've never seen one without the washer.
Is this what you are referring to as a spacer?

Steve

[LongBaz]

My original 5ltr came without a washer (spacer), short nose crank. My 4.8ltr needs one.
A word of warning, get this sorted ASAP my bolt snapped on the 5ltr when it came loose. A PITA to get fixed. Had to get it drilled out as it broke inside the nose.

[flyingdutchie]

If you look at:

http://www.v8engines.com/engine-4.htm


and sroll down until you see the crank pulleys, RPI writes about a spacer. Maybe me, but i do not understand when such a spacer should be used.

[carsy]

If you have a 4.6 crank which is a long nose crank then you need the spacer. The spacer goes on first then the big washer and bolt. Its to keep everything pulled up other wise you end up just tightening the bolt onto the crank nose and the pulley is free to float up and down the crank nose.

[flyingdutchie]

Thank you guys. It is a 4.6 crank now and what we did was putting it back as it was on the 3.9.

[flyingdutchie]

The spacer has arrived. Quite a big thing. Haven't tried it yet, but does it stick so much forwardor is it my imagination?

[NZ fan]

if the spacer is needed there will be enough crankshaft sticking out of the centre of the pulley to slide the spacer on but obviously the spacer needs to clamp the pulley on to the shaft when the bolt is tightened so the face of the spacer needs to be proud of the crankshaft before the bolt is tightened. if you see what i mean?