In readiness for the arrival of my broken V6 I have been reading up on cam belts, changing and position of engine.
I understand the inlet and exhaust valves can touch if link belt is off and pistons can touch valves if main belt is off. I understand that crank at safe position keeps pistons halfway to allow cams to be turned and if link belt is on then valves cannot touch each other.
Here's the problem. The PO, for reasons I may find out when I pick it up, has removed the main belt.
How can I put the engine into safe position without fear of hitting valves with pistons and worse, if the link belts are also off how can I align the cams without the valves having a fight when out of alignment?

I want to get crank and all cams in the correct position for belts, but how can I rotate each without damaging something else??

Can it be done?
The engine apparently had new head gaskets, new cam belt then it knocked. Garage said it needed new big ends. It didn't knock before the work!!
My plan is to align the engine, fit belts and see what happens. I have read that drained hydraulic lifters can sound fairly bad, also, of course, the pistons and valves may have got to know each other too well in the process.

Any guidance /tips much appreciated.

It is possible to do. You need to do it by "feel", basically turning the crankshaft over slowly with minimal effort. If the crank stops turning, then a piston has touched a valve, and you'll need to find out which piston has touched, so you can rotate the correct cam to allow it to clear. Don't force the crankshaft or camshaft, as it's possible to bend a valve, but a gentle touch won't hurt anything.

Once the crank "safe" position is found, then lock the crankshaft with a suitable diameter pin or drill shank.

You can spin the cams from this point onwards. I don't believe the valves will touch each other, as there's plenty of space between them, it's definitely not something I've ever worried about.

The link belts are used as the datum point, for alignment of the front belt.
Here's how the link belt alignment is done.
The red dots mark where V cutouts on the pulley should face each other, and be central if a straight edge is placed across the centre of the bolts. Hope that makes sense.

Thanks. Will probs take out spark plugs so that the compression doesn't snatch the crank out of my hand and do damage.

Just curious why, when a garage has done the belts and condemned the big ends, you'd take the belt off again?!

All will be revealed!!

andyfreelandy said:

Just curious why, when a garage has done the belts and condemned the big ends, you'd take the belt off again?!

Click to expand...

That is weird.

I've a 32K miles crankshaft with bearings if you're interested?

Thanks, let me have a good look and listen first. Me thinks they foobarred the belt fitting, heard a big noise, took belt off to destroy evidence and gave it back with the big end story. But I am very sinical!!

Got 96k on the clock, big ends should be fine unless it has never had an oil change.